org.apache.commons.lang3.ClassUtils Maven / Gradle / Ivy
/*
* 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.Arrays;
import java.util.Collections;
import java.util.Comparator;
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.Objects;
import java.util.Set;
import java.util.stream.Collectors;
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
}
private static final Comparator> COMPARATOR = (o1, o2) -> Objects.compare(getName(o1), getName(o2), String::compareTo);
/**
* 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 {@link 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 {@link Class}es to their corresponding wrapper {@link 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 {@link Class}es to their corresponding primitive types.
*/
private static final Map, Class> wrapperPrimitiveMap = new HashMap<>();
static {
primitiveWrapperMap.forEach((primitiveClass, wrapperClass) -> {
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 map = new HashMap<>();
map.put("int", "I");
map.put("boolean", "Z");
map.put("float", "F");
map.put("long", "J");
map.put("short", "S");
map.put("byte", "B");
map.put("double", "D");
map.put("char", "C");
abbreviationMap = Collections.unmodifiableMap(map);
reverseAbbreviationMap = Collections.unmodifiableMap(map.entrySet().stream().collect(Collectors.toMap(Map.Entry::getValue, Map.Entry::getKey)));
}
/**
* Gets the class comparator, comparing by class name.
*
* @return the class comparator.
* @since 3.13.0
*/
public static Comparator> comparator() {
return COMPARATOR;
}
/**
* Given a {@link List} of {@link Class} objects, this method converts them into class names.
*
*
* A new {@link List} is returned. {@code null} objects will be copied into the returned list as {@code null}.
*
*
* @param classes the classes to change
* @return a {@link List} of class names corresponding to the Class objects, {@code null} if null input
* @throws ClassCastException if {@code classes} contains a non-{@link Class} entry
*/
public static List convertClassesToClassNames(final List> classes) {
return classes == null ? null : classes.stream().map(e -> getName(e, null)).collect(Collectors.toList());
}
/**
* Given a {@link List} of class names, this method converts them into classes.
*
*
* A new {@link List} is returned. If the class name cannot be found, {@code null} is stored in the {@link List}. If the
* class name in the {@link List} is {@code null}, {@code null} is stored in the output {@link List}.
*
*
* @param classNames the classNames to change
* @return a {@link 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());
classNames.forEach(className -> {
try {
classes.add(Class.forName(className));
} catch (final Exception ex) {
classes.add(null);
}
});
return classes;
}
/**
* Gets the abbreviated name of a {@link 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 {@link 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
*
* className
* len
* return
*
*
* 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);
}
/**
* Gets a {@link 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 {@link 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 {@link 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();
}
}
/**
* Gets a {@link List} of superclasses for the given class.
*
* @param cls the class to look up, may be {@code null}
* @return the {@link 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 the canonical class name for a {@link 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 {@link 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 {@link 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 {@link 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;
}
/**
* 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 $} separators in case the class is inner class.
*
*
*
* Example:
*
* - {@code getCanonicalName("[I") = "int[]"}
* - {@code getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"}
* - {@code getCanonicalName("java.lang.String") = "java.lang.String"}
*
*
*
* @param className the name of class
* @return canonical form of class name
* @since 2.4
*/
private static String getCanonicalName(String className) {
className = StringUtils.deleteWhitespace(className);
if (className == null) {
return null;
}
int dim = 0;
while (className.startsWith("[")) {
dim++;
className = className.substring(1);
}
if (dim < 1) {
return className;
}
if (className.startsWith("L")) {
className = className.substring(1, className.endsWith(";") ? className.length() - 1 : className.length());
} else if (!className.isEmpty()) {
className = reverseAbbreviationMap.get(className.substring(0, 1));
}
final StringBuilder canonicalClassNameBuffer = new StringBuilder(className);
for (int i = 0; i < dim; i++) {
canonicalClassNameBuffer.append("[]");
}
return canonicalClassNameBuffer.toString();
}
/**
* Returns the (initialized) class represented by {@code className} using the {@code classLoader}. This implementation
* supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}",
* "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}".
*
* @param classLoader the class loader to use to load the class
* @param className the class name
* @return the class represented by {@code className} using the {@code classLoader}
* @throws NullPointerException if the className is null
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(final ClassLoader classLoader, final String className) throws ClassNotFoundException {
return getClass(classLoader, className, true);
}
/**
* Returns the class represented by {@code className} using the {@code classLoader}. This implementation supports the
* syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", and
* "{@code [Ljava.util.Map$Entry;}".
*
* @param classLoader the class loader to use to load the class
* @param className the class name
* @param initialize whether the class must be initialized
* @return the class represented by {@code className} using the {@code classLoader}
* @throws NullPointerException if the className is null
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(final ClassLoader classLoader, final String className, final boolean initialize) throws ClassNotFoundException {
try {
Class clazz = namePrimitiveMap.get(className);
return clazz != null ? clazz : Class.forName(toCanonicalName(className), initialize, classLoader);
} catch (final ClassNotFoundException ex) {
// allow path separators (.) as inner class name separators
final int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
if (lastDotIndex != -1) {
try {
return getClass(classLoader, className.substring(0, lastDotIndex) + INNER_CLASS_SEPARATOR_CHAR + className.substring(lastDotIndex + 1),
initialize);
} catch (final ClassNotFoundException ignored) {
// ignore exception
}
}
throw ex;
}
}
/**
* Returns the (initialized) class represented by {@code className} using the current thread's context class loader.
* This implementation supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}",
* "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}".
*
* @param className the class name
* @return the class represented by {@code className} using the current thread's context class loader
* @throws NullPointerException if the className is null
* @throws ClassNotFoundException if the class is not found
*/
public static Class getClass(final String className) throws ClassNotFoundException {
return getClass(className, true);
}
/**
* Returns the class represented by {@code className} using the current thread's context class loader. This
* implementation supports the syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$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 NullPointerException if the className is null
* @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);
}
/**
* Delegates to {@link Class#getComponentType()} using generics.
*
* @param The array class type.
* @param cls A class or null.
* @return The array component type or null.
* @see Class#getComponentType()
* @since 3.13.0
*/
@SuppressWarnings("unchecked")
public static Class getComponentType(final Class cls) {
return cls == null ? null : (Class) cls.getComponentType();
}
/**
* 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();
}
/**
* Gets the package name from the canonical name of a {@link 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 of an {@link 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 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));
}
/**
* Gets the package name of a {@link 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 of an {@link 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 from a {@link 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);
}
/**
* 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 (isPublic(declaredMethod.getDeclaringClass())) {
return declaredMethod;
}
final List> candidateClasses = new ArrayList<>(getAllInterfaces(cls));
candidateClasses.addAll(getAllSuperclasses(cls));
for (final Class candidateClass : candidateClasses) {
if (!isPublic(candidateClass)) {
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));
}
/**
* Gets the canonical name minus the package name from a {@link 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
* @see Class#getCanonicalName()
*/
public static String getShortCanonicalName(final Class cls) {
return cls == null ? StringUtils.EMPTY : getShortCanonicalName(cls.getCanonicalName());
}
/**
* Gets the canonical name minus the package name for an {@link 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
* @see Class#getCanonicalName()
*/
public static String getShortCanonicalName(final Object object, final String valueIfNull) {
return object == null ? valueIfNull : getShortCanonicalName(object.getClass().getCanonicalName());
}
/**
* 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 value
* input
*
*
* {@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));
}
/**
* Gets the class name minus the package name from a {@link Class}.
*
*
* This method simply gets the name using {@code Class.getName()} and then calls {@link #getShortClassName(String)}. 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 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 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 {@link 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();
}
/**
* 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.emptyIterator();
@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;
}
@Override
public void remove() {
throw new UnsupportedOperationException();
}
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);
}
}
};
};
}
/**
* Checks if one {@link Class} can be assigned to a variable of another {@link 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 {@link Class} parameter can be
* converted to the type represented by this {@link 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 {@link Class} can be assigned to a variable of another {@link 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 {@link Class} parameter can be
* converted to the type represented by this {@link 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) || 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);
}
/**
* 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 {@link Class} parameter can be
* converted to the type represented by this {@link 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 {@link Class} parameter can be
* converted to the type represented by this {@link 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;
}
/**
* 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;
}
/**
* 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);
}
/**
* Tests whether a {@link Class} is public.
* @param cls Class to test.
* @return {@code true} if {@code cls} is public.
* @since 3.13.0
*/
public static boolean isPublic(final Class cls) {
return Modifier.isPublic(cls.getModifiers());
}
/**
* 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];
Arrays.setAll(convertedClasses, i -> primitiveToWrapper(classes[i]));
return convertedClasses;
}
/**
* 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 a class name to a JLS style class name.
*
* @param className the class name
* @return the converted name
* @throws NullPointerException if the className is null
*/
private static String toCanonicalName(final String className) {
String canonicalName = StringUtils.deleteWhitespace(className);
Objects.requireNonNull(canonicalName, "className");
if (canonicalName.endsWith("[]")) {
final StringBuilder classNameBuffer = new StringBuilder();
while (canonicalName.endsWith("[]")) {
canonicalName = canonicalName.substring(0, canonicalName.length() - 2);
classNameBuffer.append("[");
}
final String abbreviation = abbreviationMap.get(canonicalName);
if (abbreviation != null) {
classNameBuffer.append(abbreviation);
} else {
classNameBuffer.append("L").append(canonicalName).append(";");
}
canonicalName = classNameBuffer.toString();
}
return canonicalName;
}
/**
* Converts an array of {@link Object} in to an array of {@link 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 {@link Object} array
* @return a {@link Class} array, {@code null} if null array input
* @since 2.4
*/
public static Class[] toClass(final Object... array) {
if (array == null) {
return null;
}
if (array.length == 0) {
return ArrayUtils.EMPTY_CLASS_ARRAY;
}
final Class[] classes = new Class[array.length];
Arrays.setAll(classes, i -> array[i] == null ? null : array[i].getClass());
return classes;
}
/**
* 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;
}
/**
* 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];
Arrays.setAll(convertedClasses, i -> wrapperToPrimitive(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);
}
/**
* 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() {
}
}