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Java 1.8+ Library with tons of utility classes required in all projects
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/*
* Copyright (C) 2014-2024 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* Licensed 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 com.helger.commons.lang;
import java.io.InputStream;
import java.lang.reflect.Modifier;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.net.URL;
import javax.annotation.Nonnull;
import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.Nonempty;
import com.helger.commons.annotation.PresentForCodeCoverage;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.collection.impl.CommonsWeakHashMap;
import com.helger.commons.collection.impl.ICommonsMap;
import com.helger.commons.collection.impl.ICommonsSet;
import com.helger.commons.io.stream.StreamHelper;
import com.helger.commons.string.StringHelper;
/**
* {@link Class} helper methods.
*
* @author Philip Helger
*/
@Immutable
public final class ClassHelper
{
// WeakHashMap because class is used as a key
private static final ICommonsMap , Class > PRIMITIVE_TO_WRAPPER = new CommonsWeakHashMap <> (8);
private static final ICommonsMap , Class > WRAPPER_TO_PRIMITIVE = new CommonsWeakHashMap <> (8);
static
{
_registerPrimitiveMapping (boolean.class, Boolean.class);
_registerPrimitiveMapping (byte.class, Byte.class);
_registerPrimitiveMapping (char.class, Character.class);
_registerPrimitiveMapping (double.class, Double.class);
_registerPrimitiveMapping (float.class, Float.class);
_registerPrimitiveMapping (int.class, Integer.class);
_registerPrimitiveMapping (long.class, Long.class);
_registerPrimitiveMapping (short.class, Short.class);
}
private static void _registerPrimitiveMapping (@Nonnull final Class aPrimitiveType, @Nonnull final Class aPrimitiveWrapperType)
{
PRIMITIVE_TO_WRAPPER.put (aPrimitiveType, aPrimitiveWrapperType);
WRAPPER_TO_PRIMITIVE.put (aPrimitiveWrapperType, aPrimitiveType);
}
@PresentForCodeCoverage
private static final ClassHelper INSTANCE = new ClassHelper ();
private ClassHelper ()
{}
public static boolean isPublicClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
// Interfaces or annotations are not allowed
if (aClass.isInterface () || aClass.isAnnotation ())
return false;
// Only public classes are allowed
if (!isPublic (aClass))
return false;
// Abstract classes are not allowed
if (isAbstractClass (aClass))
return false;
return true;
}
/**
* Check if the passed class is public, instancable and has a no-argument
* constructor.
*
* @param aClass
* The class to check. May be null.
* @return true if the class is public, instancable and has a
* no-argument constructor that is public.
*/
public static boolean isInstancableClass (@Nullable final Class aClass)
{
if (!isPublicClass (aClass))
return false;
// Check if a default constructor is present
try
{
aClass.getConstructor ((Class []) null);
}
catch (final NoSuchMethodException ex)
{
return false;
}
return true;
}
public static boolean isPublic (@Nullable final Class aClass)
{
return aClass != null && Modifier.isPublic (aClass.getModifiers ());
}
/**
* Check if the passed class is an interface or not. Please note that
* annotations are also interfaces!
*
* @param aClass
* The class to check.
* @return true if the class is an interface (or an annotation)
*/
public static boolean isInterface (@Nullable final Class aClass)
{
return aClass != null && Modifier.isInterface (aClass.getModifiers ());
}
public static boolean isAnnotationClass (@Nullable final Class aClass)
{
return aClass != null && aClass.isAnnotation ();
}
public static boolean isEnumClass (@Nullable final Class aClass)
{
return aClass != null && aClass.isEnum ();
}
/**
* Check if the passed class is abstract or not. Note: interfaces and
* annotations are also considered as abstract whereas arrays are never
* abstract.
*
* @param aClass
* The class to check.
* @return true if the passed class is abstract
*/
public static boolean isAbstractClass (@Nullable final Class aClass)
{
// Special case for arrays (see documentation of Class.getModifiers: only
// final and interface are set, the rest is indeterministic)
return aClass != null && !aClass.isArray () && Modifier.isAbstract (aClass.getModifiers ());
}
public static boolean isArrayClass (@Nullable final Class aClass)
{
return aClass != null && aClass.isArray ();
}
public static boolean isPrimitiveType (@Nullable final Class aClass)
{
return aClass != null && PRIMITIVE_TO_WRAPPER.containsKey (aClass);
}
public static boolean isPrimitiveWrapperType (@Nullable final Class aClass)
{
return aClass != null && WRAPPER_TO_PRIMITIVE.containsKey (aClass);
}
/**
* Get the primitive wrapper class of the passed primitive class.
*
* @param aClass
* The primitive class. May be null.
* @return null if the passed class is not a primitive class.
*/
@Nullable
public static Class getPrimitiveWrapperClass (@Nullable final Class aClass)
{
if (isPrimitiveWrapperType (aClass))
return aClass;
return PRIMITIVE_TO_WRAPPER.get (aClass);
}
/**
* Get the primitive class of the passed primitive wrapper class.
*
* @param aClass
* The primitive wrapper class. May be null.
* @return null if the passed class is not a primitive wrapper
* class.
*/
@Nullable
public static Class getPrimitiveClass (@Nullable final Class aClass)
{
if (isPrimitiveType (aClass))
return aClass;
return WRAPPER_TO_PRIMITIVE.get (aClass);
}
@Nonnull
@ReturnsMutableCopy
public static ICommonsSet > getAllPrimitiveClasses ()
{
return PRIMITIVE_TO_WRAPPER.copyOfKeySet ();
}
@Nonnull
@ReturnsMutableCopy
public static ICommonsSet > getAllPrimitiveWrapperClasses ()
{
return WRAPPER_TO_PRIMITIVE.copyOfKeySet ();
}
public static boolean isStringClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
// Base class of String, StringBuffer and StringBuilder
return CharSequence.class.isAssignableFrom (aClass);
}
public static boolean isCharacterClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
return Character.class.isAssignableFrom (aClass) || char.class.isAssignableFrom (aClass);
}
public static boolean isBooleanClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
return Boolean.class.isAssignableFrom (aClass) || boolean.class.isAssignableFrom (aClass);
}
public static boolean isFloatingPointClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
return Double.class.isAssignableFrom (aClass) ||
double.class.isAssignableFrom (aClass) ||
Float.class.isAssignableFrom (aClass) ||
float.class.isAssignableFrom (aClass) ||
BigDecimal.class.isAssignableFrom (aClass);
}
public static boolean isIntegerClass (@Nullable final Class aClass)
{
if (aClass == null)
return false;
return Byte.class.isAssignableFrom (aClass) ||
byte.class.isAssignableFrom (aClass) ||
Integer.class.isAssignableFrom (aClass) ||
int.class.isAssignableFrom (aClass) ||
Long.class.isAssignableFrom (aClass) ||
long.class.isAssignableFrom (aClass) ||
Short.class.isAssignableFrom (aClass) ||
short.class.isAssignableFrom (aClass) ||
BigInteger.class.isAssignableFrom (aClass);
}
/**
* Check if the passed classes are convertible. Includes conversion checks
* between primitive types and primitive wrapper types.
*
* @param aSrcClass
* First class. May not be null.
* @param aDstClass
* Second class. May not be null.
* @return true if the classes are directly convertible.
*/
public static boolean areConvertibleClasses (@Nonnull final Class aSrcClass, @Nonnull final Class aDstClass)
{
ValueEnforcer.notNull (aSrcClass, "SrcClass");
ValueEnforcer.notNull (aDstClass, "DstClass");
// Same class?
if (aDstClass.equals (aSrcClass))
return true;
// Default assignable
if (aDstClass.isAssignableFrom (aSrcClass))
return true;
// Special handling for "int.class" == "Integer.class" etc.
if (aDstClass == getPrimitiveWrapperClass (aSrcClass))
return true;
if (aDstClass == getPrimitiveClass (aSrcClass))
return true;
// Not convertible
return false;
}
/**
* null-safe helper method to determine the class of an object.
*
* @param aObject
* The object to query. May be null.
* @return null if the passed object is null.
*/
@Nullable
public static Class getClass (@Nullable final Object aObject)
{
return aObject == null ? null : aObject.getClass ();
}
/**
* null-safe helper method to determine the class name of an
* object.
*
* @param aObject
* The object to query. May be null.
* @return null if the passed object is null.
*/
@Nullable
public static String getClassName (@Nullable final Object aObject)
{
return aObject == null ? null : aObject.getClass ().getName ();
}
/**
* Get the name of the object's class without the package.
*
* @param aObject
* The object to get the information from. May be null .
* @return The local name of the passed object's class.
*/
@Nullable
public static String getClassLocalName (@Nullable final Object aObject)
{
return aObject == null ? null : getClassLocalName (aObject.getClass ());
}
/**
* Get the name of the class without the package.
*
* @param aClass
* The class to get the information from. May be null.
* @return The local name of the passed class.
*/
@Nullable
public static String getClassLocalName (@Nullable final Class aClass)
{
return aClass == null ? null : getClassLocalName (aClass.getName ());
}
/**
* Get the name of the class without the package.
*
* @param sClassName
* The fully qualified name of the class. May be null.
* @return The local name of the passed class. Never null.
*/
@Nullable
public static String getClassLocalName (@Nullable final String sClassName)
{
if (sClassName == null)
return null;
final int nIndex = sClassName.lastIndexOf ('.');
return nIndex == -1 ? sClassName : sClassName.substring (nIndex + 1);
}
/**
* Get the name of the package the passed object resides in.
*
* @param aObject
* The class to get the information from. May be null.
* @return The package name of the passed object.
*/
@Nullable
public static String getClassPackageName (@Nullable final Object aObject)
{
return aObject == null ? null : getClassPackageName (aObject.getClass ());
}
/**
* Get the name of the package the passed class resides in.
*
* @param aClass
* The class to get the information from. May not be null.
* @return The package name of the passed class.
*/
@Nullable
public static String getClassPackageName (@Nullable final Class aClass)
{
return aClass == null ? null : getClassPackageName (aClass.getName ());
}
/**
* Get the name of the package the passed class resides in.
*
* @param sClassName
* The name class to get the information from. May be null
* .
* @return The package name of the passed class.
*/
@Nullable
public static String getClassPackageName (@Nullable final String sClassName)
{
if (sClassName == null)
return null;
final int nIndex = sClassName.lastIndexOf ('.');
return nIndex == -1 ? "" : sClassName.substring (0, nIndex);
}
/**
* Get the class name of the passed object. If the object itself is of type
* {@link Class}, its name is retrieved, other {@link #getClass()} is called.
*
* @param aObject
* The object who's class name is to be retrieved.
* @return "null" for a null parameter
*/
@Nonnull
@Nonempty
public static String getSafeClassName (@Nullable final Object aObject)
{
if (aObject instanceof Class )
return ((Class ) aObject).getName ();
if (aObject != null)
return aObject.getClass ().getName ();
return "null";
}
/**
* Convert a package name to a relative directory name.
*
* @param aPackage
* The package to be converted. May be null.
* @return The directory name using forward slashes (/) instead of the dots.
*/
@Nullable
public static String getDirectoryFromPackage (@Nullable final Package aPackage)
{
// No differentiation
return aPackage == null ? null : getPathFromClass (aPackage.getName ());
}
/**
* Convert a package name to a relative directory name.
*
* @param sPackage
* The name of the package to be converted. May be null.
* @return The directory name using forward slashes (/) instead of the dots.
*/
@Nullable
public static String getDirectoryFromPackage (@Nullable final String sPackage)
{
// No differentiation
return getPathFromClass (sPackage);
}
/**
* Get the path representation of the passed class. The path representation is
* achieved by replacing all dots (.) with forward slashes (/) in the class
* name.
*
* @param aClass
* The class of which the path is to be retrieved. May be
* null.
* @return The path representation. Never null.
*/
@Nullable
public static String getPathFromClass (@Nullable final Class aClass)
{
return aClass == null ? null : getPathFromClass (aClass.getName ());
}
/**
* Get the path representation of the passed class name. The path
* representation is achieved by replacing all dots (.) with forward slashes
* (/) in the class name.
*
* @param sClassName
* The class name of which the path is to be retrieved. May be
* null.
* @return The path representation
*/
@Nullable
public static String getPathFromClass (@Nullable final String sClassName)
{
return sClassName == null ? null : StringHelper.replaceAll (sClassName, '.', '/');
}
/**
* Get the class name of the passed path. The class name is retrieved by
* replacing all path separators (\ and /) with dots (.). This method does not
* handle the file extension, so it's up to the caller to skip of any file
* extension!
*
* @param sPath
* The path to be converted. May be null.
* @return The class name.
*/
@Nullable
public static String getClassFromPath (@Nullable final String sPath)
{
return sPath == null ? null : StringHelper.replaceMultipleAsString (sPath, new char [] { '\\', '/' }, '.');
}
/**
* Get the hex representation of the passed object's address. Note that this
* method makes no differentiation between 32 and 64 bit architectures. The
* result is always a hexadecimal value preceded by "0x" and followed by
* exactly 8 characters.
*
* @param aObject
* The object who's address is to be retrieved. May be
* null.
* @return Depending on the current architecture. Always starting with "0x"
* and than containing the address.
* @see System#identityHashCode(Object)
*/
@Nonnull
@Nonempty
public static String getObjectAddress (@Nullable final Object aObject)
{
if (aObject == null)
return "0x00000000";
return "0x" + StringHelper.getHexStringLeadingZero (System.identityHashCode (aObject), 8);
}
@Nonnull
private static String _getPathWithLeadingSlash (@Nonnull @Nonempty final String sPath)
{
return sPath.charAt (0) == '/' ? sPath : "/" + sPath;
}
/**
* Get the URL of the passed resource using the class loader of the specified
* class only. This is a sanity wrapper around
* class.getResource (sPath).
*
* @param aClass
* The class to be used. May not be null.
* @param sPath
* The path to be resolved. May neither be null nor empty.
* Internally it is ensured that the provided path does start with a
* slash.
* @return null if the path could not be resolved using the
* specified class loader.
*/
@Nullable
public static URL getResource (@Nonnull final Class aClass, @Nonnull @Nonempty final String sPath)
{
ValueEnforcer.notNull (aClass, "Class");
ValueEnforcer.notEmpty (sPath, "Path");
// Ensure the path does start with a "/"
final String sPathWithSlash = _getPathWithLeadingSlash (sPath);
// returns null if not found
return aClass.getResource (sPathWithSlash);
}
/**
* Get the input stream of the passed resource using the class loader of the
* specified class only. This is a sanity wrapper around
* class.getResourceAsStream (sPath).
*
* @param aClass
* The class to be used. May not be null.
* @param sPath
* The path to be resolved. May neither be null nor empty.
* Internally it is ensured that the provided path does start with a
* slash.
* @return null if the path could not be resolved using the
* specified class loader.
*/
@Nullable
public static InputStream getResourceAsStream (@Nonnull final Class aClass, @Nonnull @Nonempty final String sPath)
{
ValueEnforcer.notNull (aClass, "Class");
ValueEnforcer.notEmpty (sPath, "Path");
// Ensure the path does start with a "/"
final String sPathWithSlash = _getPathWithLeadingSlash (sPath);
// returns null if not found
final InputStream aIS = aClass.getResourceAsStream (sPathWithSlash);
return StreamHelper.checkForInvalidFilterInputStream (aIS);
}
}