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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.commons.lang3;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

import org.apache.commons.lang3.mutable.MutableObject;

/**
 * 

Operates on classes without using reflection.

* *

This class handles invalid {@code null} inputs as best it can. * Each method documents its behavior in more detail.

* *

The notion of a {@code canonical name} includes the human * readable name for the type, for example {@code int[]}. The * non-canonical method variants work with the JVM names, such as * {@code [I}.

* * @since 2.0 */ public class ClassUtils { /** * Inclusivity literals for {@link #hierarchy(Class, Interfaces)}. * @since 3.2 */ public enum Interfaces { /** Includes interfaces. */ INCLUDE, /** Excludes interfaces. */ EXCLUDE } /** * The package separator character: {@code '.' == {@value}}. */ public static final char PACKAGE_SEPARATOR_CHAR = '.'; /** * The package separator String: {@code "."}. */ public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR); /** * The inner class separator character: {@code '$' == {@value}}. */ public static final char INNER_CLASS_SEPARATOR_CHAR = '$'; /** * The inner class separator String: {@code "$"}. */ public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR); /** * Maps names of primitives to their corresponding primitive {@code Class}es. */ private static final Map> namePrimitiveMap = new HashMap<>(); static { namePrimitiveMap.put("boolean", Boolean.TYPE); namePrimitiveMap.put("byte", Byte.TYPE); namePrimitiveMap.put("char", Character.TYPE); namePrimitiveMap.put("short", Short.TYPE); namePrimitiveMap.put("int", Integer.TYPE); namePrimitiveMap.put("long", Long.TYPE); namePrimitiveMap.put("double", Double.TYPE); namePrimitiveMap.put("float", Float.TYPE); namePrimitiveMap.put("void", Void.TYPE); } /** * Maps primitive {@code Class}es to their corresponding wrapper {@code Class}. */ private static final Map, Class> primitiveWrapperMap = new HashMap<>(); static { primitiveWrapperMap.put(Boolean.TYPE, Boolean.class); primitiveWrapperMap.put(Byte.TYPE, Byte.class); primitiveWrapperMap.put(Character.TYPE, Character.class); primitiveWrapperMap.put(Short.TYPE, Short.class); primitiveWrapperMap.put(Integer.TYPE, Integer.class); primitiveWrapperMap.put(Long.TYPE, Long.class); primitiveWrapperMap.put(Double.TYPE, Double.class); primitiveWrapperMap.put(Float.TYPE, Float.class); primitiveWrapperMap.put(Void.TYPE, Void.TYPE); } /** * Maps wrapper {@code Class}es to their corresponding primitive types. */ private static final Map, Class> wrapperPrimitiveMap = new HashMap<>(); static { for (final Map.Entry, Class> entry : primitiveWrapperMap.entrySet()) { final Class primitiveClass = entry.getKey(); final Class wrapperClass = entry.getValue(); if (!primitiveClass.equals(wrapperClass)) { wrapperPrimitiveMap.put(wrapperClass, primitiveClass); } } } /** * Maps a primitive class name to its corresponding abbreviation used in array class names. */ private static final Map abbreviationMap; /** * Maps an abbreviation used in array class names to corresponding primitive class name. */ private static final Map reverseAbbreviationMap; // Feed abbreviation maps static { final Map m = new HashMap<>(); m.put("int", "I"); m.put("boolean", "Z"); m.put("float", "F"); m.put("long", "J"); m.put("short", "S"); m.put("byte", "B"); m.put("double", "D"); m.put("char", "C"); final Map r = new HashMap<>(); for (final Map.Entry e : m.entrySet()) { r.put(e.getValue(), e.getKey()); } abbreviationMap = Collections.unmodifiableMap(m); reverseAbbreviationMap = Collections.unmodifiableMap(r); } /** *

ClassUtils instances should NOT be constructed in standard programming. * Instead, the class should be used as * {@code ClassUtils.getShortClassName(cls)}.

* *

This constructor is public to permit tools that require a JavaBean * instance to operate.

*/ public ClassUtils() { } // Short class name // ---------------------------------------------------------------------- /** *

Gets the class name of the {@code object} without the package name or names.

* *

The method looks up the class of the object and then converts the name of the class invoking * {@link #getShortClassName(Class)} (see relevant notes there).

* * @param object the class to get the short name for, may be {@code null} * @param valueIfNull the value to return if the object is {@code null} * @return the class name of the object without the package name, or {@code valueIfNull} * if the argument {@code object} is {@code null} */ public static String getShortClassName(final Object object, final String valueIfNull) { if (object == null) { return valueIfNull; } return getShortClassName(object.getClass()); } /** *

Gets the class name minus the package name from a {@code Class}.

* *

This method simply gets the name using {@code Class.getName()} and then calls * {@link #getShortClassName(Class)}. See relevant notes there.

* * @param cls the class to get the short name for. * @return the class name without the package name or an empty string. If the class * is an inner class then the returned value will contain the outer class * or classes separated with {@code .} (dot) character. */ public static String getShortClassName(final Class cls) { if (cls == null) { return StringUtils.EMPTY; } return getShortClassName(cls.getName()); } /** *

Gets the class name minus the package name from a String.

* *

The string passed in is assumed to be a class name - it is not checked. The string has to be formatted the way * as the JDK method {@code Class.getName()} returns it, and not the usual way as we write it, for example in import * statements, or as it is formatted by {@code Class.getCanonicalName()}.

* *

The difference is is significant only in case of classes that are inner classes of some other * classes. In this case the separator between the outer and inner class (possibly on multiple hierarchy level) has * to be {@code $} (dollar sign) and not {@code .} (dot), as it is returned by {@code Class.getName()}

* *

Note that this method is called from the {@link #getShortClassName(Class)} method using the string * returned by {@code Class.getName()}.

* *

Note that this method differs from {@link #getSimpleName(Class)} in that this will * return, for example {@code "Map.Entry"} whilst the {@code java.lang.Class} variant will simply * return {@code "Entry"}. In this example the argument {@code className} is the string * {@code java.util.Map$Entry} (note the {@code $} sign.

* * @param className the className to get the short name for. It has to be formatted as returned by * {@code Class.getName()} and not {@code Class.getCanonicalName()} * @return the class name of the class without the package name or an empty string. If the class is * an inner class then value contains the outer class or classes and the separator is replaced * to be {@code .} (dot) character. */ public static String getShortClassName(String className) { if (StringUtils.isEmpty(className)) { return StringUtils.EMPTY; } final StringBuilder arrayPrefix = new StringBuilder(); // Handle array encoding if (className.startsWith("[")) { while (className.charAt(0) == '[') { className = className.substring(1); arrayPrefix.append("[]"); } // Strip Object type encoding if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') { className = className.substring(1, className.length() - 1); } if (reverseAbbreviationMap.containsKey(className)) { className = reverseAbbreviationMap.get(className); } } final int lastDotIdx = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); final int innerIdx = className.indexOf( INNER_CLASS_SEPARATOR_CHAR, lastDotIdx == -1 ? 0 : lastDotIdx + 1); String out = className.substring(lastDotIdx + 1); if (innerIdx != -1) { out = out.replace(INNER_CLASS_SEPARATOR_CHAR, PACKAGE_SEPARATOR_CHAR); } return out + arrayPrefix; } /** *

Null-safe version of {@code cls.getSimpleName()}

* * @param cls the class for which to get the simple name; may be null * @return the simple class name or the empty string in case the argument is {@code null} * @since 3.0 * @see Class#getSimpleName() */ public static String getSimpleName(final Class cls) { return getSimpleName(cls, StringUtils.EMPTY); } /** *

Null-safe version of {@code cls.getSimpleName()}

* * @param cls the class for which to get the simple name; may be null * @param valueIfNull the value to return if null * @return the simple class name or {@code valueIfNull} if the * argument {@code cls} is {@code null} * @since 3.0 * @see Class#getSimpleName() */ public static String getSimpleName(final Class cls, final String valueIfNull) { return cls == null ? valueIfNull : cls.getSimpleName(); } /** *

Null-safe version of {@code object.getClass().getSimpleName()}

* *

It is to note that this method is overloaded and in case the argument {@code object} is a * {@code Class} object then the {@link #getSimpleName(Class)} will be invoked. If this is * a significant possibility then the caller should check this case and call {@code * getSimpleName(Class.class)} or just simply use the string literal {@code "Class"}, which * is the result of the method in that case.

* * @param object the object for which to get the simple class name; may be null * @return the simple class name or the empty string in case the argument is {@code null} * @since 3.7 * @see Class#getSimpleName() */ public static String getSimpleName(final Object object) { return getSimpleName(object, StringUtils.EMPTY); } /** *

Null-safe version of {@code object.getClass().getSimpleName()}

* * @param object the object for which to get the simple class name; may be null * @param valueIfNull the value to return if {@code object} is {@code null} * @return the simple class name or {@code valueIfNull} if the * argument {@code object} is {@code null} * @since 3.0 * @see Class#getSimpleName() */ public static String getSimpleName(final Object object, final String valueIfNull) { return object == null ? valueIfNull : object.getClass().getSimpleName(); } /** *

Null-safe version of {@code cls.getName()}

* * @param cls the class for which to get the class name; may be null * @return the class name or the empty string in case the argument is {@code null} * @since 3.7 * @see Class#getSimpleName() */ public static String getName(final Class cls) { return getName(cls, StringUtils.EMPTY); } /** *

Null-safe version of {@code cls.getName()}

* * @param cls the class for which to get the class name; may be null * @param valueIfNull the return value if the argument {@code cls} is {@code null} * @return the class name or {@code valueIfNull} * @since 3.7 * @see Class#getName() */ public static String getName(final Class cls, final String valueIfNull) { return cls == null ? valueIfNull : cls.getName(); } /** *

Null-safe version of {@code object.getClass().getName()}

* * @param object the object for which to get the class name; may be null * @return the class name or the empty String * @since 3.7 * @see Class#getSimpleName() */ public static String getName(final Object object) { return getName(object, StringUtils.EMPTY); } /** *

Null-safe version of {@code object.getClass().getSimpleName()}

* * @param object the object for which to get the class name; may be null * @param valueIfNull the value to return if {@code object} is {@code null} * @return the class name or {@code valueIfNull} * @since 3.0 * @see Class#getName() */ public static String getName(final Object object, final String valueIfNull) { return object == null ? valueIfNull : object.getClass().getName(); } // Package name // ---------------------------------------------------------------------- /** *

Gets the package name of an {@code Object}.

* * @param object the class to get the package name for, may be null * @param valueIfNull the value to return if null * @return the package name of the object, or the null value */ public static String getPackageName(final Object object, final String valueIfNull) { if (object == null) { return valueIfNull; } return getPackageName(object.getClass()); } /** *

Gets the package name of a {@code Class}.

* * @param cls the class to get the package name for, may be {@code null}. * @return the package name or an empty string */ public static String getPackageName(final Class cls) { if (cls == null) { return StringUtils.EMPTY; } return getPackageName(cls.getName()); } /** *

Gets the package name from a {@code String}.

* *

The string passed in is assumed to be a class name - it is not checked.

*

If the class is unpackaged, return an empty string.

* * @param className the className to get the package name for, may be {@code null} * @return the package name or an empty string */ public static String getPackageName(String className) { if (StringUtils.isEmpty(className)) { return StringUtils.EMPTY; } // Strip array encoding while (className.charAt(0) == '[') { className = className.substring(1); } // Strip Object type encoding if (className.charAt(0) == 'L' && className.charAt(className.length() - 1) == ';') { className = className.substring(1); } final int i = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (i == -1) { return StringUtils.EMPTY; } return className.substring(0, i); } // Abbreviated name // ---------------------------------------------------------------------- /** *

Gets the abbreviated name of a {@code Class}.

* * @param cls the class to get the abbreviated name for, may be {@code null} * @param lengthHint the desired length of the abbreviated name * @return the abbreviated name or an empty string * @throws IllegalArgumentException if len <= 0 * @see #getAbbreviatedName(String, int) * @since 3.4 */ public static String getAbbreviatedName(final Class cls, final int lengthHint) { if (cls == null) { return StringUtils.EMPTY; } return getAbbreviatedName(cls.getName(), lengthHint); } /** *

Gets the abbreviated class name from a {@code String}.

* *

The string passed in is assumed to be a class name - it is not checked.

* *

The abbreviation algorithm will shorten the class name, usually without * significant loss of meaning.

* *

The abbreviated class name will always include the complete package hierarchy. * If enough space is available, rightmost sub-packages will be displayed in full * length. The abbreviated package names will be shortened to a single character.

*

Only package names are shortened, the class simple name remains untouched. (See examples.)

*

The result will be longer than the desired length only if all the package names * shortened to a single character plus the class simple name with the separating dots * together are longer than the desired length. In other words, when the class name * cannot be shortened to the desired length.

*

If the class name can be shortened then * the final length will be at most {@code lengthHint} characters.

*

If the {@code lengthHint} is zero or negative then the method * throws exception. If you want to achieve the shortest possible version then * use {@code 1} as a {@code lengthHint}.

* * * * * * * * * *
Examples
classNamelenreturn
null 1""
"java.lang.String" 5"j.l.String"
"java.lang.String"15"j.lang.String"
"java.lang.String"30"java.lang.String"
"org.apache.commons.lang3.ClassUtils"18"o.a.c.l.ClassUtils"
* * @param className the className to get the abbreviated name for, may be {@code null} * @param lengthHint the desired length of the abbreviated name * @return the abbreviated name or an empty string if the specified * class name is {@code null} or empty string. The abbreviated name may be * longer than the desired length if it cannot be abbreviated to the desired length. * @throws IllegalArgumentException if {@code len <= 0} * @since 3.4 */ public static String getAbbreviatedName(final String className, final int lengthHint) { if (lengthHint <= 0) { throw new IllegalArgumentException("len must be > 0"); } if (className == null) { return StringUtils.EMPTY; } if (className.length() <= lengthHint) { return className; } final char[] abbreviated = className.toCharArray(); int target = 0; int source = 0; while (source < abbreviated.length) { // copy the next part int runAheadTarget = target; while (source < abbreviated.length && abbreviated[source] != '.') { abbreviated[runAheadTarget++] = abbreviated[source++]; } ++target; if (useFull(runAheadTarget, source, abbreviated.length, lengthHint) || target > runAheadTarget) { target = runAheadTarget; } // copy the '.' unless it was the last part if (source < abbreviated.length) { abbreviated[target++] = abbreviated[source++]; } } return new String(abbreviated, 0, target); } /** *

Decides if the part that was just copied to its destination * location in the work array can be kept as it was copied or must be * abbreviated. It must be kept when the part is the last one, which * is the simple name of the class. In this case the {@code source} * index, from where the characters are copied points one position * after the last character, a.k.a. {@code source == * originalLength}

* *

If the part is not the last one then it can be kept * unabridged if the number of the characters copied so far plus * the character that are to be copied is less than or equal to the * desired length.

* * @param runAheadTarget the target index (where the characters were * copied to) pointing after the last character * copied when the current part was copied * @param source the source index (where the characters were * copied from) pointing after the last * character copied when the current part was * copied * @param originalLength the original length of the class full name, * which is abbreviated * @param desiredLength the desired length of the abbreviated class * name * @return {@code true} if it can be kept in its original length * {@code false} if the current part has to be abbreviated and */ private static boolean useFull(final int runAheadTarget, final int source, final int originalLength, final int desiredLength) { return source >= originalLength || runAheadTarget + originalLength - source <= desiredLength; } // Superclasses/Superinterfaces // ---------------------------------------------------------------------- /** *

Gets a {@code List} of superclasses for the given class.

* * @param cls the class to look up, may be {@code null} * @return the {@code List} of superclasses in order going up from this one * {@code null} if null input */ public static List> getAllSuperclasses(final Class cls) { if (cls == null) { return null; } final List> classes = new ArrayList<>(); Class superclass = cls.getSuperclass(); while (superclass != null) { classes.add(superclass); superclass = superclass.getSuperclass(); } return classes; } /** *

Gets a {@code List} of all interfaces implemented by the given * class and its superclasses.

* *

The order is determined by looking through each interface in turn as * declared in the source file and following its hierarchy up. Then each * superclass is considered in the same way. Later duplicates are ignored, * so the order is maintained.

* * @param cls the class to look up, may be {@code null} * @return the {@code List} of interfaces in order, * {@code null} if null input */ public static List> getAllInterfaces(final Class cls) { if (cls == null) { return null; } final LinkedHashSet> interfacesFound = new LinkedHashSet<>(); getAllInterfaces(cls, interfacesFound); return new ArrayList<>(interfacesFound); } /** * Gets the interfaces for the specified class. * * @param cls the class to look up, may be {@code null} * @param interfacesFound the {@code Set} of interfaces for the class */ private static void getAllInterfaces(Class cls, final HashSet> interfacesFound) { while (cls != null) { final Class[] interfaces = cls.getInterfaces(); for (final Class i : interfaces) { if (interfacesFound.add(i)) { getAllInterfaces(i, interfacesFound); } } cls = cls.getSuperclass(); } } // Convert list // ---------------------------------------------------------------------- /** *

Given a {@code List} of class names, this method converts them into classes.

* *

A new {@code List} is returned. If the class name cannot be found, {@code null} * is stored in the {@code List}. If the class name in the {@code List} is * {@code null}, {@code null} is stored in the output {@code List}.

* * @param classNames the classNames to change * @return a {@code List} of Class objects corresponding to the class names, * {@code null} if null input * @throws ClassCastException if classNames contains a non String entry */ public static List> convertClassNamesToClasses(final List classNames) { if (classNames == null) { return null; } final List> classes = new ArrayList<>(classNames.size()); for (final String className : classNames) { try { classes.add(Class.forName(className)); } catch (final Exception ex) { classes.add(null); } } return classes; } /** *

Given a {@code List} of {@code Class} objects, this method converts * them into class names.

* *

A new {@code List} is returned. {@code null} objects will be copied into * the returned list as {@code null}.

* * @param classes the classes to change * @return a {@code List} of class names corresponding to the Class objects, * {@code null} if null input * @throws ClassCastException if {@code classes} contains a non-{@code Class} entry */ public static List convertClassesToClassNames(final List> classes) { if (classes == null) { return null; } final List classNames = new ArrayList<>(classes.size()); for (final Class cls : classes) { if (cls == null) { classNames.add(null); } else { classNames.add(cls.getName()); } } return classNames; } // Is assignable // ---------------------------------------------------------------------- /** *

Checks if an array of Classes can be assigned to another array of Classes.

* *

This method calls {@link #isAssignable(Class, Class) isAssignable} for each * Class pair in the input arrays. It can be used to check if a set of arguments * (the first parameter) are suitably compatible with a set of method parameter types * (the second parameter).

* *

Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this * method takes into account widenings of primitive classes and * {@code null}s.

* *

Primitive widenings allow an int to be assigned to a {@code long}, * {@code float} or {@code double}. This method returns the correct * result for these cases.

* *

{@code Null} may be assigned to any reference type. This method will * return {@code true} if {@code null} is passed in and the toClass is * non-primitive.

* *

Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * The Java Language Specification, * sections 5.1.1, 5.1.2 and 5.1.4 for details.

* *

Since Lang 3.0, this method will default behavior for * calculating assignability between primitive and wrapper types corresponding * to the running Java version; i.e. autoboxing will be the default * behavior in VMs running Java versions > 1.5.

* * @param classArray the array of Classes to check, may be {@code null} * @param toClassArray the array of Classes to try to assign into, may be {@code null} * @return {@code true} if assignment possible */ public static boolean isAssignable(final Class[] classArray, final Class... toClassArray) { return isAssignable(classArray, toClassArray, true); } /** *

Checks if an array of Classes can be assigned to another array of Classes.

* *

This method calls {@link #isAssignable(Class, Class) isAssignable} for each * Class pair in the input arrays. It can be used to check if a set of arguments * (the first parameter) are suitably compatible with a set of method parameter types * (the second parameter).

* *

Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this * method takes into account widenings of primitive classes and * {@code null}s.

* *

Primitive widenings allow an int to be assigned to a {@code long}, * {@code float} or {@code double}. This method returns the correct * result for these cases.

* *

{@code Null} may be assigned to any reference type. This method will * return {@code true} if {@code null} is passed in and the toClass is * non-primitive.

* *

Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * The Java Language Specification, * sections 5.1.1, 5.1.2 and 5.1.4 for details.

* * @param classArray the array of Classes to check, may be {@code null} * @param toClassArray the array of Classes to try to assign into, may be {@code null} * @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers * @return {@code true} if assignment possible */ public static boolean isAssignable(Class[] classArray, Class[] toClassArray, final boolean autoboxing) { if (!ArrayUtils.isSameLength(classArray, toClassArray)) { return false; } if (classArray == null) { classArray = ArrayUtils.EMPTY_CLASS_ARRAY; } if (toClassArray == null) { toClassArray = ArrayUtils.EMPTY_CLASS_ARRAY; } for (int i = 0; i < classArray.length; i++) { if (!isAssignable(classArray[i], toClassArray[i], autoboxing)) { return false; } } return true; } /** * Returns whether the given {@code type} is a primitive or primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, * {@link Short}, {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * * @param type * The class to query or null. * @return true if the given {@code type} is a primitive or primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, * {@link Short}, {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * @since 3.1 */ public static boolean isPrimitiveOrWrapper(final Class type) { if (type == null) { return false; } return type.isPrimitive() || isPrimitiveWrapper(type); } /** * Returns whether the given {@code type} is a primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, {@link Short}, * {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * * @param type * The class to query or null. * @return true if the given {@code type} is a primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, {@link Short}, * {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * @since 3.1 */ public static boolean isPrimitiveWrapper(final Class type) { return wrapperPrimitiveMap.containsKey(type); } /** *

Checks if one {@code Class} can be assigned to a variable of * another {@code Class}.

* *

Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, * this method takes into account widenings of primitive classes and * {@code null}s.

* *

Primitive widenings allow an int to be assigned to a long, float or * double. This method returns the correct result for these cases.

* *

{@code Null} may be assigned to any reference type. This method * will return {@code true} if {@code null} is passed in and the * toClass is non-primitive.

* *

Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * The Java Language Specification, * sections 5.1.1, 5.1.2 and 5.1.4 for details.

* *

Since Lang 3.0, this method will default behavior for * calculating assignability between primitive and wrapper types corresponding * to the running Java version; i.e. autoboxing will be the default * behavior in VMs running Java versions > 1.5.

* * @param cls the Class to check, may be null * @param toClass the Class to try to assign into, returns false if null * @return {@code true} if assignment possible */ public static boolean isAssignable(final Class cls, final Class toClass) { return isAssignable(cls, toClass, true); } /** *

Checks if one {@code Class} can be assigned to a variable of * another {@code Class}.

* *

Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, * this method takes into account widenings of primitive classes and * {@code null}s.

* *

Primitive widenings allow an int to be assigned to a long, float or * double. This method returns the correct result for these cases.

* *

{@code Null} may be assigned to any reference type. This method * will return {@code true} if {@code null} is passed in and the * toClass is non-primitive.

* *

Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * The Java Language Specification, * sections 5.1.1, 5.1.2 and 5.1.4 for details.

* * @param cls the Class to check, may be null * @param toClass the Class to try to assign into, returns false if null * @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers * @return {@code true} if assignment possible */ public static boolean isAssignable(Class cls, final Class toClass, final boolean autoboxing) { if (toClass == null) { return false; } // have to check for null, as isAssignableFrom doesn't if (cls == null) { return !toClass.isPrimitive(); } //autoboxing: if (autoboxing) { if (cls.isPrimitive() && !toClass.isPrimitive()) { cls = primitiveToWrapper(cls); if (cls == null) { return false; } } if (toClass.isPrimitive() && !cls.isPrimitive()) { cls = wrapperToPrimitive(cls); if (cls == null) { return false; } } } if (cls.equals(toClass)) { return true; } if (cls.isPrimitive()) { if (!toClass.isPrimitive()) { return false; } if (Integer.TYPE.equals(cls)) { return Long.TYPE.equals(toClass) || Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass); } if (Long.TYPE.equals(cls)) { return Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass); } if (Boolean.TYPE.equals(cls)) { return false; } if (Double.TYPE.equals(cls)) { return false; } if (Float.TYPE.equals(cls)) { return Double.TYPE.equals(toClass); } if (Character.TYPE.equals(cls)) { return Integer.TYPE.equals(toClass) || Long.TYPE.equals(toClass) || Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass); } if (Short.TYPE.equals(cls)) { return Integer.TYPE.equals(toClass) || Long.TYPE.equals(toClass) || Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass); } if (Byte.TYPE.equals(cls)) { return Short.TYPE.equals(toClass) || Integer.TYPE.equals(toClass) || Long.TYPE.equals(toClass) || Float.TYPE.equals(toClass) || Double.TYPE.equals(toClass); } // should never get here return false; } return toClass.isAssignableFrom(cls); } /** *

Converts the specified primitive Class object to its corresponding * wrapper Class object.

* *

NOTE: From v2.2, this method handles {@code Void.TYPE}, * returning {@code Void.TYPE}.

* * @param cls the class to convert, may be null * @return the wrapper class for {@code cls} or {@code cls} if * {@code cls} is not a primitive. {@code null} if null input. * @since 2.1 */ public static Class primitiveToWrapper(final Class cls) { Class convertedClass = cls; if (cls != null && cls.isPrimitive()) { convertedClass = primitiveWrapperMap.get(cls); } return convertedClass; } /** *

Converts the specified array of primitive Class objects to an array of * its corresponding wrapper Class objects.

* * @param classes the class array to convert, may be null or empty * @return an array which contains for each given class, the wrapper class or * the original class if class is not a primitive. {@code null} if null input. * Empty array if an empty array passed in. * @since 2.1 */ public static Class[] primitivesToWrappers(final Class... classes) { if (classes == null) { return null; } if (classes.length == 0) { return classes; } final Class[] convertedClasses = new Class[classes.length]; for (int i = 0; i < classes.length; i++) { convertedClasses[i] = primitiveToWrapper(classes[i]); } return convertedClasses; } /** *

Converts the specified wrapper class to its corresponding primitive * class.

* *

This method is the counter part of {@code primitiveToWrapper()}. * If the passed in class is a wrapper class for a primitive type, this * primitive type will be returned (e.g. {@code Integer.TYPE} for * {@code Integer.class}). For other classes, or if the parameter is * null, the return value is null.

* * @param cls the class to convert, may be null * @return the corresponding primitive type if {@code cls} is a * wrapper class, null otherwise * @see #primitiveToWrapper(Class) * @since 2.4 */ public static Class wrapperToPrimitive(final Class cls) { return wrapperPrimitiveMap.get(cls); } /** *

Converts the specified array of wrapper Class objects to an array of * its corresponding primitive Class objects.

* *

This method invokes {@code wrapperToPrimitive()} for each element * of the passed in array.

* * @param classes the class array to convert, may be null or empty * @return an array which contains for each given class, the primitive class or * null if the original class is not a wrapper class. {@code null} if null input. * Empty array if an empty array passed in. * @see #wrapperToPrimitive(Class) * @since 2.4 */ public static Class[] wrappersToPrimitives(final Class... classes) { if (classes == null) { return null; } if (classes.length == 0) { return classes; } final Class[] convertedClasses = new Class[classes.length]; for (int i = 0; i < classes.length; i++) { convertedClasses[i] = wrapperToPrimitive(classes[i]); } return convertedClasses; } // Inner class // ---------------------------------------------------------------------- /** *

Is the specified class an inner class or static nested class.

* * @param cls the class to check, may be null * @return {@code true} if the class is an inner or static nested class, * false if not or {@code null} */ public static boolean isInnerClass(final Class cls) { return cls != null && cls.getEnclosingClass() != null; } // Class loading // ---------------------------------------------------------------------- /** * Returns the class represented by {@code className} using the * {@code classLoader}. This implementation supports the syntaxes * "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", * "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}". * * @param classLoader the class loader to use to load the class * @param className the class name * @param initialize whether the class must be initialized * @return the class represented by {@code className} using the {@code classLoader} * @throws ClassNotFoundException if the class is not found */ public static Class getClass( final ClassLoader classLoader, final String className, final boolean initialize) throws ClassNotFoundException { try { final Class clazz; if (namePrimitiveMap.containsKey(className)) { clazz = namePrimitiveMap.get(className); } else { clazz = Class.forName(toCanonicalName(className), initialize, classLoader); } return clazz; } catch (final ClassNotFoundException ex) { // allow path separators (.) as inner class name separators final int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (lastDotIndex != -1) { try { return getClass(classLoader, className.substring(0, lastDotIndex) + INNER_CLASS_SEPARATOR_CHAR + className.substring(lastDotIndex + 1), initialize); } catch (final ClassNotFoundException ex2) { // NOPMD // ignore exception } } throw ex; } } /** * Returns the (initialized) class represented by {@code className} * using the {@code classLoader}. This implementation supports * the syntaxes "{@code java.util.Map.Entry[]}", * "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", * and "{@code [Ljava.util.Map$Entry;}". * * @param classLoader the class loader to use to load the class * @param className the class name * @return the class represented by {@code className} using the {@code classLoader} * @throws ClassNotFoundException if the class is not found */ public static Class getClass(final ClassLoader classLoader, final String className) throws ClassNotFoundException { return getClass(classLoader, className, true); } /** * Returns the (initialized) class represented by {@code className} * using the current thread's context class loader. This implementation * supports the syntaxes "{@code java.util.Map.Entry[]}", * "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", * and "{@code [Ljava.util.Map$Entry;}". * * @param className the class name * @return the class represented by {@code className} using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class getClass(final String className) throws ClassNotFoundException { return getClass(className, true); } /** * Returns the class represented by {@code className} using the * current thread's context class loader. This implementation supports the * syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", * "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}". * * @param className the class name * @param initialize whether the class must be initialized * @return the class represented by {@code className} using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class getClass(final String className, final boolean initialize) throws ClassNotFoundException { final ClassLoader contextCL = Thread.currentThread().getContextClassLoader(); final ClassLoader loader = contextCL == null ? ClassUtils.class.getClassLoader() : contextCL; return getClass(loader, className, initialize); } // Public method // ---------------------------------------------------------------------- /** *

Returns the desired Method much like {@code Class.getMethod}, however * it ensures that the returned Method is from a public class or interface and not * from an anonymous inner class. This means that the Method is invokable and * doesn't fall foul of Java bug * 4071957).

* *
     *  Set set = Collections.unmodifiableSet(...);
     *  Method method = ClassUtils.getPublicMethod(set.getClass(), "isEmpty",  new Class[0]);
     *  Object result = method.invoke(set, new Object[]);
     *  
* * @param cls the class to check, not null * @param methodName the name of the method * @param parameterTypes the list of parameters * @return the method * @throws NullPointerException if the class is null * @throws SecurityException if a security violation occurred * @throws NoSuchMethodException if the method is not found in the given class * or if the method doesn't conform with the requirements */ public static Method getPublicMethod(final Class cls, final String methodName, final Class... parameterTypes) throws NoSuchMethodException { final Method declaredMethod = cls.getMethod(methodName, parameterTypes); if (Modifier.isPublic(declaredMethod.getDeclaringClass().getModifiers())) { return declaredMethod; } final List> candidateClasses = new ArrayList<>(getAllInterfaces(cls)); candidateClasses.addAll(getAllSuperclasses(cls)); for (final Class candidateClass : candidateClasses) { if (!Modifier.isPublic(candidateClass.getModifiers())) { continue; } final Method candidateMethod; try { candidateMethod = candidateClass.getMethod(methodName, parameterTypes); } catch (final NoSuchMethodException ex) { continue; } if (Modifier.isPublic(candidateMethod.getDeclaringClass().getModifiers())) { return candidateMethod; } } throw new NoSuchMethodException("Can't find a public method for " + methodName + " " + ArrayUtils.toString(parameterTypes)); } // ---------------------------------------------------------------------- /** * Converts a class name to a JLS style class name. * * @param className the class name * @return the converted name */ private static String toCanonicalName(String className) { className = StringUtils.deleteWhitespace(className); Validate.notNull(className, "className"); if (className.endsWith("[]")) { final StringBuilder classNameBuffer = new StringBuilder(); while (className.endsWith("[]")) { className = className.substring(0, className.length() - 2); classNameBuffer.append("["); } final String abbreviation = abbreviationMap.get(className); if (abbreviation != null) { classNameBuffer.append(abbreviation); } else { classNameBuffer.append("L").append(className).append(";"); } className = classNameBuffer.toString(); } return className; } /** *

Converts an array of {@code Object} in to an array of {@code Class} objects. * If any of these objects is null, a null element will be inserted into the array.

* *

This method returns {@code null} for a {@code null} input array.

* * @param array an {@code Object} array * @return a {@code Class} array, {@code null} if null array input * @since 2.4 */ public static Class[] toClass(final Object... array) { if (array == null) { return null; } else if (array.length == 0) { return ArrayUtils.EMPTY_CLASS_ARRAY; } final Class[] classes = new Class[array.length]; for (int i = 0; i < array.length; i++) { classes[i] = array[i] == null ? null : array[i].getClass(); } return classes; } // Short canonical name // ---------------------------------------------------------------------- /** *

Gets the canonical name minus the package name for an {@code Object}.

* * @param object the class to get the short name for, may be null * @param valueIfNull the value to return if null * @return the canonical name of the object without the package name, or the null value * @since 2.4 */ public static String getShortCanonicalName(final Object object, final String valueIfNull) { if (object == null) { return valueIfNull; } return getShortCanonicalName(object.getClass().getName()); } /** *

Gets the canonical class name for a {@code Class}.

* * @param cls the class for which to get the canonical class name; may be null * @return the canonical name of the class, or the empty String * @since 3.7 * @see Class#getCanonicalName() */ public static String getCanonicalName(final Class cls) { return getCanonicalName(cls, StringUtils.EMPTY); } /** *

Gets the canonical name for a {@code Class}.

* * @param cls the class for which to get the canonical class name; may be null * @param valueIfNull the return value if null * @return the canonical name of the class, or {@code valueIfNull} * @since 3.7 * @see Class#getCanonicalName() */ public static String getCanonicalName(final Class cls, final String valueIfNull) { if (cls == null) { return valueIfNull; } final String canonicalName = cls.getCanonicalName(); return canonicalName == null ? valueIfNull : canonicalName; } /** *

Gets the canonical name for an {@code Object}.

* * @param object the object for which to get the canonical class name; may be null * @return the canonical name of the object, or the empty String * @since 3.7 * @see Class#getCanonicalName() */ public static String getCanonicalName(final Object object) { return getCanonicalName(object, StringUtils.EMPTY); } /** *

Gets the canonical name for an {@code Object}.

* * @param object the object for which to get the canonical class name; may be null * @param valueIfNull the return value if null * @return the canonical name of the object or {@code valueIfNull} * @since 3.7 * @see Class#getCanonicalName() */ public static String getCanonicalName(final Object object, final String valueIfNull) { if (object == null) { return valueIfNull; } final String canonicalName = object.getClass().getCanonicalName(); return canonicalName == null ? valueIfNull : canonicalName; } /** *

Gets the canonical name minus the package name from a {@code Class}.

* * @param cls the class for which to get the short canonical class name; may be null * @return the canonical name without the package name or an empty string * @since 2.4 */ public static String getShortCanonicalName(final Class cls) { if (cls == null) { return StringUtils.EMPTY; } return getShortCanonicalName(cls.getName()); } /** *

Gets the canonical name minus the package name from a String.

* *

The string passed in is assumed to be a class name - it is not checked.

* *

Note that this method is mainly designed to handle the arrays and primitives properly. * If the class is an inner class then the result value will not contain the outer classes. * This way the behavior of this method is different from {@link #getShortClassName(String)}. * The argument in that case is class name and not canonical name and the return value * retains the outer classes.

* *

Note that there is no way to reliably identify the part of the string representing the * package hierarchy and the part that is the outer class or classes in case of an inner class. * Trying to find the class would require reflective call and the class itself may not even be * on the class path. Relying on the fact that class names start with capital letter and packages * with lower case is heuristic.

* *

It is recommended to use {@link #getShortClassName(String)} for cases when the class * is an inner class and use this method for cases it is designed for.

* * * * * * * * * * * * * * * * * * *
Examples
return valueinput
{@code ""}{@code (String)null}
{@code "Map.Entry"}{@code java.util.Map.Entry.class.getName()}
{@code "Entry"}{@code java.util.Map.Entry.class.getCanonicalName()}
{@code "ClassUtils"}{@code "org.apache.commons.lang3.ClassUtils"}
{@code "ClassUtils[]"}{@code "[Lorg.apache.commons.lang3.ClassUtils;"}
{@code "ClassUtils[][]"}{@code "[[Lorg.apache.commons.lang3.ClassUtils;"}
{@code "ClassUtils[]"}{@code "org.apache.commons.lang3.ClassUtils[]"}
{@code "ClassUtils[][]"}{@code "org.apache.commons.lang3.ClassUtils[][]"}
{@code "int[]"}{@code "[I"}
{@code "int[]"}{@code int[].class.getCanonicalName()}
{@code "int[]"}{@code int[].class.getName()}
{@code "int[][]"}{@code "[[I"}
{@code "int[]"}{@code "int[]"}
{@code "int[][]"}{@code "int[][]"}
* * @param canonicalName the class name to get the short name for * @return the canonical name of the class without the package name or an empty string * @since 2.4 */ public static String getShortCanonicalName(final String canonicalName) { return getShortClassName(getCanonicalName(canonicalName)); } // Package name // ---------------------------------------------------------------------- /** *

Gets the package name from the class name of an {@code Object}.

* * @param object the class to get the package name for, may be null * @param valueIfNull the value to return if null * @return the package name of the object, or the null value * @since 2.4 */ public static String getPackageCanonicalName(final Object object, final String valueIfNull) { if (object == null) { return valueIfNull; } return getPackageCanonicalName(object.getClass().getName()); } /** *

Gets the package name from the canonical name of a {@code Class}.

* * @param cls the class to get the package name for, may be {@code null}. * @return the package name or an empty string * @since 2.4 */ public static String getPackageCanonicalName(final Class cls) { if (cls == null) { return StringUtils.EMPTY; } return getPackageCanonicalName(cls.getName()); } /** *

Gets the package name from the class name.

* *

The string passed in is assumed to be a class name - it is not checked.

*

If the class is in the default package, return an empty string.

* * @param name the name to get the package name for, may be {@code null} * @return the package name or an empty string * @since 2.4 */ public static String getPackageCanonicalName(final String name) { return getPackageName(getCanonicalName(name)); } /** *

Converts a given name of class into canonical format. * If name of class is not a name of array class it returns * unchanged name.

* *

The method does not change the {@code $} separators in case * the class is inner class.

* *

Example: *

    *
  • {@code getCanonicalName("[I") = "int[]"}
  • *
  • {@code getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"}
  • *
  • {@code getCanonicalName("java.lang.String") = "java.lang.String"}
  • *
*

* * @param className the name of class * @return canonical form of class name * @since 2.4 */ private static String getCanonicalName(String className) { className = StringUtils.deleteWhitespace(className); if (className == null) { return null; } int dim = 0; while (className.startsWith("[")) { dim++; className = className.substring(1); } if (dim < 1) { return className; } if (className.startsWith("L")) { className = className.substring( 1, className.endsWith(";") ? className.length() - 1 : className.length()); } else if (!className.isEmpty()) { className = reverseAbbreviationMap.get(className.substring(0, 1)); } final StringBuilder canonicalClassNameBuffer = new StringBuilder(className); for (int i = 0; i < dim; i++) { canonicalClassNameBuffer.append("[]"); } return canonicalClassNameBuffer.toString(); } /** * Gets an {@link Iterable} that can iterate over a class hierarchy in ascending (subclass to superclass) order, * excluding interfaces. * * @param type the type to get the class hierarchy from * @return Iterable an Iterable over the class hierarchy of the given class * @since 3.2 */ public static Iterable> hierarchy(final Class type) { return hierarchy(type, Interfaces.EXCLUDE); } /** * Gets an {@link Iterable} that can iterate over a class hierarchy in ascending (subclass to superclass) order. * * @param type the type to get the class hierarchy from * @param interfacesBehavior switch indicating whether to include or exclude interfaces * @return Iterable an Iterable over the class hierarchy of the given class * @since 3.2 */ public static Iterable> hierarchy(final Class type, final Interfaces interfacesBehavior) { final Iterable> classes = () -> { final MutableObject> next = new MutableObject<>(type); return new Iterator>() { @Override public boolean hasNext() { return next.getValue() != null; } @Override public Class next() { final Class result = next.getValue(); next.setValue(result.getSuperclass()); return result; } @Override public void remove() { throw new UnsupportedOperationException(); } }; }; if (interfacesBehavior != Interfaces.INCLUDE) { return classes; } return () -> { final Set> seenInterfaces = new HashSet<>(); final Iterator> wrapped = classes.iterator(); return new Iterator>() { Iterator> interfaces = Collections.>emptySet().iterator(); @Override public boolean hasNext() { return interfaces.hasNext() || wrapped.hasNext(); } @Override public Class next() { if (interfaces.hasNext()) { final Class nextInterface = interfaces.next(); seenInterfaces.add(nextInterface); return nextInterface; } final Class nextSuperclass = wrapped.next(); final Set> currentInterfaces = new LinkedHashSet<>(); walkInterfaces(currentInterfaces, nextSuperclass); interfaces = currentInterfaces.iterator(); return nextSuperclass; } private void walkInterfaces(final Set> addTo, final Class c) { for (final Class iface : c.getInterfaces()) { if (!seenInterfaces.contains(iface)) { addTo.add(iface); } walkInterfaces(addTo, iface); } } @Override public void remove() { throw new UnsupportedOperationException(); } }; }; } }




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