Java tutorial
/* * 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.lang; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.ArrayList; import java.util.HashMap; import java.util.HashSet; import java.util.LinkedHashSet; import java.util.List; import java.util.Map; /** * <p>Operates on classes without using reflection.</p> * * <p>This class handles invalid <code>null</code> inputs as best it can. * Each method documents its behaviour in more detail.</p> * * <p>The notion of a <code>canonical name</code> includes the human * readable name for the type, for example <code>int[]</code>. The * non-canonical method variants work with the JVM names, such as * <code>[I</code>. </p> * * @author Stephen Colebourne * @author Gary Gregory * @author Norm Deane * @author Alban Peignier * @author Tomasz Blachowicz * @since 2.0 * @version $Id$ */ public class ClassUtils { /** * <p>The package separator character: <code>'.' == {@value}</code>.</p> */ public static final char PACKAGE_SEPARATOR_CHAR = '.'; /** * <p>The package separator String: <code>"."</code>.</p> */ public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR); /** * <p>The inner class separator character: <code>'$' == {@value}</code>.</p> */ public static final char INNER_CLASS_SEPARATOR_CHAR = '$'; /** * <p>The inner class separator String: <code>"$"</code>.</p> */ public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR); /** * Maps primitive <code>Class</code>es to their corresponding wrapper <code>Class</code>. */ private static final Map<Class<?>, Class<?>> primitiveWrapperMap = new HashMap<Class<?>, Class<?>>(); 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</code>es to their corresponding primitive types. */ private static final Map<Class<?>, Class<?>> wrapperPrimitiveMap = new HashMap<Class<?>, Class<?>>(); static { for (Class<?> primitiveClass : primitiveWrapperMap.keySet()) { Class<?> wrapperClass = primitiveWrapperMap.get(primitiveClass); 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<String, String> abbreviationMap = new HashMap<String, String>(); /** * Maps an abbreviation used in array class names to corresponding primitive class name. */ private static final Map<String, String> reverseAbbreviationMap = new HashMap<String, String>(); /** * Add primitive type abbreviation to maps of abbreviations. * * @param primitive Canonical name of primitive type * @param abbreviation Corresponding abbreviation of primitive type */ private static void addAbbreviation(String primitive, String abbreviation) { abbreviationMap.put(primitive, abbreviation); reverseAbbreviationMap.put(abbreviation, primitive); } /** * Feed abbreviation maps */ static { addAbbreviation("int", "I"); addAbbreviation("boolean", "Z"); addAbbreviation("float", "F"); addAbbreviation("long", "J"); addAbbreviation("short", "S"); addAbbreviation("byte", "B"); addAbbreviation("double", "D"); addAbbreviation("char", "C"); } /** * <p>ClassUtils instances should NOT be constructed in standard programming. * Instead, the class should be used as * <code>ClassUtils.getShortClassName(cls)</code>.</p> * * <p>This constructor is public to permit tools that require a JavaBean * instance to operate.</p> */ public ClassUtils() { super(); } // Short class name // ---------------------------------------------------------------------- /** * <p>Gets the class name minus the package name for an <code>Object</code>.</p> * * @param object the class to get the short name for, may be null * @param valueIfNull the value to return if null * @return the class name of the object without the package name, or the null value */ public static String getShortClassName(Object object, String valueIfNull) { if (object == null) { return valueIfNull; } return getShortClassName(object.getClass()); } /** * <p>Gets the class name minus the package name from a <code>Class</code>.</p> * * @param cls the class to get the short name for. * @return the class name without the package name or an empty string */ public static String getShortClassName(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return getShortClassName(cls.getName()); } /** * <p>Gets the class name minus the package name from a String.</p> * * <p>The string passed in is assumed to be a class name - it is not checked.</p> * * @param className the className to get the short name for * @return the class name of the class without the package name or an empty string */ public static String getShortClassName(String className) { if (className == null) { return StringUtils.EMPTY; } if (className.length() == 0) { return StringUtils.EMPTY; } StringBuffer arrayPrefix = new StringBuffer(); // 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); } int lastDotIdx = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); 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; } // Package name // ---------------------------------------------------------------------- /** * <p>Gets the package name of an <code>Object</code>.</p> * * @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(Object object, String valueIfNull) { if (object == null) { return valueIfNull; } return getPackageName(object.getClass()); } /** * <p>Gets the package name of a <code>Class</code>.</p> * * @param cls the class to get the package name for, may be <code>null</code>. * @return the package name or an empty string */ public static String getPackageName(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return getPackageName(cls.getName()); } /** * <p>Gets the package name from a <code>String</code>.</p> * * <p>The string passed in is assumed to be a class name - it is not checked.</p> * <p>If the class is unpackaged, return an empty string.</p> * * @param className the className to get the package name for, may be <code>null</code> * @return the package name or an empty string */ public static String getPackageName(String className) { if (className == null || className.length() == 0) { 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); } int i = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (i == -1) { return StringUtils.EMPTY; } return className.substring(0, i); } // Superclasses/Superinterfaces // ---------------------------------------------------------------------- /** * <p>Gets a <code>List</code> of superclasses for the given class.</p> * * @param cls the class to look up, may be <code>null</code> * @return the <code>List</code> of superclasses in order going up from this one * <code>null</code> if null input */ public static List<Class<?>> getAllSuperclasses(Class<?> cls) { if (cls == null) { return null; } List<Class<?>> classes = new ArrayList<Class<?>>(); Class<?> superclass = cls.getSuperclass(); while (superclass != null) { classes.add(superclass); superclass = superclass.getSuperclass(); } return classes; } /** * <p>Gets a <code>List</code> of all interfaces implemented by the given * class and its superclasses.</p> * * <p>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.</p> * * @param cls the class to look up, may be <code>null</code> * @return the <code>List</code> of interfaces in order, * <code>null</code> if null input */ public static List<Class<?>> getAllInterfaces(Class<?> cls) { if (cls == null) { return null; } LinkedHashSet<Class<?>> interfacesFound = new LinkedHashSet<Class<?>>(); getAllInterfaces(cls, interfacesFound); return new ArrayList<Class<?>>(interfacesFound); } private static void getAllInterfaces(Class<?> cls, HashSet<Class<?>> interfacesFound) { while (cls != null) { Class<?>[] interfaces = cls.getInterfaces(); for (Class<?> i : interfaces) { if (interfacesFound.add(i)) { getAllInterfaces(i, interfacesFound); } } cls = cls.getSuperclass(); } } // Convert list // ---------------------------------------------------------------------- /** * <p>Given a <code>List</code> of class names, this method converts them into classes.</p> * * <p>A new <code>List</code> is returned. If the class name cannot be found, <code>null</code> * is stored in the <code>List</code>. If the class name in the <code>List</code> is * <code>null</code>, <code>null</code> is stored in the output <code>List</code>.</p> * * @param classNames the classNames to change * @return a <code>List</code> of Class objects corresponding to the class names, * <code>null</code> if null input * @throws ClassCastException if classNames contains a non String entry */ public static List<Class<?>> convertClassNamesToClasses(List<String> classNames) { if (classNames == null) { return null; } List<Class<?>> classes = new ArrayList<Class<?>>(classNames.size()); for (String className : classNames) { try { classes.add(Class.forName(className)); } catch (Exception ex) { classes.add(null); } } return classes; } /** * <p>Given a <code>List</code> of <code>Class</code> objects, this method converts * them into class names.</p> * * <p>A new <code>List</code> is returned. <code>null</code> objects will be copied into * the returned list as <code>null</code>.</p> * * @param classes the classes to change * @return a <code>List</code> of class names corresponding to the Class objects, * <code>null</code> if null input * @throws ClassCastException if <code>classes</code> contains a non-<code>Class</code> entry */ public static List<String> convertClassesToClassNames(List<Class<?>> classes) { if (classes == null) { return null; } List<String> classNames = new ArrayList<String>(classes.size()); for (Class<?> cls : classes) { if (cls == null) { classNames.add(null); } else { classNames.add(cls.getName()); } } return classNames; } // Is assignable // ---------------------------------------------------------------------- /** * <p>Checks if an array of Classes can be assigned to another array of Classes.</p> * * <p>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).</p> * * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this * method takes into account widenings of primitive classes and * <code>null</code>s.</p> * * <p>Primitive widenings allow an int to be assigned to a <code>long</code>, * <code>float</code> or <code>double</code>. This method returns the correct * result for these cases.</p> * * <p><code>Null</code> may be assigned to any reference type. This method will * return <code>true</code> if <code>null</code> is passed in and the toClass is * non-primitive.</p> * * <p>Specifically, this method tests whether the type represented by the * specified <code>Class</code> parameter can be converted to the type * represented by this <code>Class</code> object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * @param classArray the array of Classes to check, may be <code>null</code> * @param toClassArray the array of Classes to try to assign into, may be <code>null</code> * @return <code>true</code> if assignment possible */ //TODO when we bump the major version we should default autoboxing to true on platforms >= 1.5 public static boolean isAssignable(Class<?>[] classArray, Class<?>[] toClassArray) { return isAssignable(classArray, toClassArray, false); } /** * <p>Checks if an array of Classes can be assigned to another array of Classes.</p> * * <p>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).</p> * * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, this * method takes into account widenings of primitive classes and * <code>null</code>s.</p> * * <p>Primitive widenings allow an int to be assigned to a <code>long</code>, * <code>float</code> or <code>double</code>. This method returns the correct * result for these cases.</p> * * <p><code>Null</code> may be assigned to any reference type. This method will * return <code>true</code> if <code>null</code> is passed in and the toClass is * non-primitive.</p> * * <p>Specifically, this method tests whether the type represented by the * specified <code>Class</code> parameter can be converted to the type * represented by this <code>Class</code> object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * @param classArray the array of Classes to check, may be <code>null</code> * @param toClassArray the array of Classes to try to assign into, may be <code>null</code> * @param autoboxing whether to use implicit autoboxing/unboxing between primitives and wrappers * @return <code>true</code> if assignment possible */ public static boolean isAssignable(Class<?>[] classArray, Class<?>[] toClassArray, boolean autoboxing) { if (ArrayUtils.isSameLength(classArray, toClassArray) == false) { 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) == false) { return false; } } return true; } /** * <p>Checks if one <code>Class</code> can be assigned to a variable of * another <code>Class</code>.</p> * * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, * this method takes into account widenings of primitive classes and * <code>null</code>s.</p> * * <p>Primitive widenings allow an int to be assigned to a long, float or * double. This method returns the correct result for these cases.</p> * * <p><code>Null</code> may be assigned to any reference type. This method * will return <code>true</code> if <code>null</code> is passed in and the * toClass is non-primitive.</p> * * <p>Specifically, this method tests whether the type represented by the * specified <code>Class</code> parameter can be converted to the type * represented by this <code>Class</code> object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * @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</code> if assignment possible */ //TODO when we bump the major version we should default autoboxing to true on platforms >= 1.5 public static boolean isAssignable(Class<?> cls, Class<?> toClass) { return isAssignable(cls, toClass, false); } /** * <p>Checks if one <code>Class</code> can be assigned to a variable of * another <code>Class</code>.</p> * * <p>Unlike the {@link Class#isAssignableFrom(java.lang.Class)} method, * this method takes into account widenings of primitive classes and * <code>null</code>s.</p> * * <p>Primitive widenings allow an int to be assigned to a long, float or * double. This method returns the correct result for these cases.</p> * * <p><code>Null</code> may be assigned to any reference type. This method * will return <code>true</code> if <code>null</code> is passed in and the * toClass is non-primitive.</p> * * <p>Specifically, this method tests whether the type represented by the * specified <code>Class</code> parameter can be converted to the type * represented by this <code>Class</code> object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://java.sun.com/docs/books/jls/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * @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</code> if assignment possible */ public static boolean isAssignable(Class<?> cls, Class<?> toClass, 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() == false) { 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); } /** * <p>Converts the specified primitive Class object to its corresponding * wrapper Class object.</p> * * <p>NOTE: From v2.2, this method handles <code>Void.TYPE</code>, * returning <code>Void.TYPE</code>.</p> * * @param cls the class to convert, may be null * @return the wrapper class for <code>cls</code> or <code>cls</code> if * <code>cls</code> is not a primitive. <code>null</code> if null input. * @since 2.1 */ public static Class<?> primitiveToWrapper(Class<?> cls) { Class<?> convertedClass = cls; if (cls != null && cls.isPrimitive()) { convertedClass = primitiveWrapperMap.get(cls); } return convertedClass; } /** * <p>Converts the specified array of primitive Class objects to an array of * its corresponding wrapper Class objects.</p> * * @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</code> if null input. * Empty array if an empty array passed in. * @since 2.1 */ public static Class<?>[] primitivesToWrappers(Class<?>[] classes) { if (classes == null) { return null; } if (classes.length == 0) { return classes; } Class<?>[] convertedClasses = new Class[classes.length]; for (int i = 0; i < classes.length; i++) { convertedClasses[i] = primitiveToWrapper(classes[i]); } return convertedClasses; } /** * <p>Converts the specified wrapper class to its corresponding primitive * class.</p> * * <p>This method is the counter part of <code>primitiveToWrapper()</code>. * If the passed in class is a wrapper class for a primitive type, this * primitive type will be returned (e.g. <code>Integer.TYPE</code> for * <code>Integer.class</code>). For other classes, or if the parameter is * <b>null</b>, the return value is <b>null</b>.</p> * * @param cls the class to convert, may be <b>null</b> * @return the corresponding primitive type if <code>cls</code> is a * wrapper class, <b>null</b> otherwise * @see #primitiveToWrapper(Class) * @since 2.4 */ public static Class<?> wrapperToPrimitive(Class<?> cls) { return wrapperPrimitiveMap.get(cls); } /** * <p>Converts the specified array of wrapper Class objects to an array of * its corresponding primitive Class objects.</p> * * <p>This method invokes <code>wrapperToPrimitive()</code> for each element * of the passed in array.</p> * * @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 * <b>null</b> if the original class is not a wrapper class. <code>null</code> if null input. * Empty array if an empty array passed in. * @see #wrapperToPrimitive(Class) * @since 2.4 */ public static Class<?>[] wrappersToPrimitives(Class<?>[] classes) { if (classes == null) { return null; } if (classes.length == 0) { return classes; } Class<?>[] convertedClasses = new Class[classes.length]; for (int i = 0; i < classes.length; i++) { convertedClasses[i] = wrapperToPrimitive(classes[i]); } return convertedClasses; } // Inner class // ---------------------------------------------------------------------- /** * <p>Is the specified class an inner class or static nested class.</p> * * @param cls the class to check, may be null * @return <code>true</code> if the class is an inner or static nested class, * false if not or <code>null</code> */ public static boolean isInnerClass(Class<?> cls) { if (cls == null) { return false; } return cls.getName().indexOf(INNER_CLASS_SEPARATOR_CHAR) >= 0; } // Class loading // ---------------------------------------------------------------------- /** * Returns the class represented by <code>className</code> using the * <code>classLoader</code>. This implementation supports names like * "<code>java.lang.String[]</code>" as well as "<code>[Ljava.lang.String;</code>". * * @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</code> using the <code>classLoader</code> * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(ClassLoader classLoader, String className, boolean initialize) throws ClassNotFoundException { Class<?> clazz; if (abbreviationMap.containsKey(className)) { String clsName = "[" + abbreviationMap.get(className); clazz = Class.forName(clsName, initialize, classLoader).getComponentType(); } else { clazz = Class.forName(toCanonicalName(className), initialize, classLoader); } return clazz; } /** * Returns the (initialized) class represented by <code>className</code> * using the <code>classLoader</code>. This implementation supports names * like "<code>java.lang.String[]</code>" as well as * "<code>[Ljava.lang.String;</code>". * * @param classLoader the class loader to use to load the class * @param className the class name * @return the class represented by <code>className</code> using the <code>classLoader</code> * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(ClassLoader classLoader, String className) throws ClassNotFoundException { return getClass(classLoader, className, true); } /** * Returns the (initialized) class represented by <code>className</code> * using the current thread's context class loader. This implementation * supports names like "<code>java.lang.String[]</code>" as well as * "<code>[Ljava.lang.String;</code>". * * @param className the class name * @return the class represented by <code>className</code> using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(String className) throws ClassNotFoundException { return getClass(className, true); } /** * Returns the class represented by <code>className</code> using the * current thread's context class loader. This implementation supports * names like "<code>java.lang.String[]</code>" as well as * "<code>[Ljava.lang.String;</code>". * * @param className the class name * @param initialize whether the class must be initialized * @return the class represented by <code>className</code> using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(String className, boolean initialize) throws ClassNotFoundException { ClassLoader contextCL = Thread.currentThread().getContextClassLoader(); ClassLoader loader = contextCL == null ? ClassUtils.class.getClassLoader() : contextCL; return getClass(loader, className, initialize); } // Public method // ---------------------------------------------------------------------- /** * <p>Returns the desired Method much like <code>Class.getMethod</code>, 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 * <a href="http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4071957">4071957</a>). * * <code><pre>Set set = Collections.unmodifiableSet(...); * Method method = ClassUtils.getPublicMethod(set.getClass(), "isEmpty", new Class[0]); * Object result = method.invoke(set, new Object[]);</pre></code> * </p> * * @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 a security violation occured * @throws NoSuchMethodException if the method is not found in the given class * or if the metothod doen't conform with the requirements */ public static Method getPublicMethod(Class<?> cls, String methodName, Class<?> parameterTypes[]) throws SecurityException, NoSuchMethodException { Method declaredMethod = cls.getMethod(methodName, parameterTypes); if (Modifier.isPublic(declaredMethod.getDeclaringClass().getModifiers())) { return declaredMethod; } List<Class<?>> candidateClasses = new ArrayList<Class<?>>(); candidateClasses.addAll(getAllInterfaces(cls)); candidateClasses.addAll(getAllSuperclasses(cls)); for (Class<?> candidateClass : candidateClasses) { if (!Modifier.isPublic(candidateClass.getModifiers())) { continue; } Method candidateMethod; try { candidateMethod = candidateClass.getMethod(methodName, parameterTypes); } catch (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); if (className == null) { throw new NullPointerException("className must not be null."); } else if (className.endsWith("[]")) { StringBuffer classNameBuffer = new StringBuffer(); while (className.endsWith("[]")) { className = className.substring(0, className.length() - 2); classNameBuffer.append("["); } String abbreviation = abbreviationMap.get(className); if (abbreviation != null) { classNameBuffer.append(abbreviation); } else { classNameBuffer.append("L").append(className).append(";"); } className = classNameBuffer.toString(); } return className; } /** * <p>Converts an array of <code>Object</code> in to an array of <code>Class</code> objects.</p> * * <p>This method returns <code>null</code> for a <code>null</code> input array.</p> * * @param array an <code>Object</code> array * @return a <code>Class</code> array, <code>null</code> if null array input * @since 2.4 */ public static Class<?>[] toClass(Object[] array) { if (array == null) { return null; } else if (array.length == 0) { return ArrayUtils.EMPTY_CLASS_ARRAY; } Class<?>[] classes = new Class[array.length]; for (int i = 0; i < array.length; i++) { classes[i] = array[i].getClass(); } return classes; } // Short canonical name // ---------------------------------------------------------------------- /** * <p>Gets the canonical name minus the package name for an <code>Object</code>.</p> * * @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(Object object, String valueIfNull) { if (object == null) { return valueIfNull; } return getShortCanonicalName(object.getClass().getName()); } /** * <p>Gets the canonical name minus the package name from a <code>Class</code>.</p> * * @param cls the class to get the short name for. * @return the canonical name without the package name or an empty string * @since 2.4 */ public static String getShortCanonicalName(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return getShortCanonicalName(cls.getName()); } /** * <p>Gets the canonical name minus the package name from a String.</p> * * <p>The string passed in is assumed to be a canonical name - it is not checked.</p> * * @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(String canonicalName) { return ClassUtils.getShortClassName(getCanonicalName(canonicalName)); } // Package name // ---------------------------------------------------------------------- /** * <p>Gets the package name from the canonical name of an <code>Object</code>.</p> * * @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(Object object, String valueIfNull) { if (object == null) { return valueIfNull; } return getPackageCanonicalName(object.getClass().getName()); } /** * <p>Gets the package name from the canonical name of a <code>Class</code>.</p> * * @param cls the class to get the package name for, may be <code>null</code>. * @return the package name or an empty string * @since 2.4 */ public static String getPackageCanonicalName(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return getPackageCanonicalName(cls.getName()); } /** * <p>Gets the package name from the canonical name. </p> * * <p>The string passed in is assumed to be a canonical name - it is not checked.</p> * <p>If the class is unpackaged, return an empty string.</p> * * @param canonicalName the canonical name to get the package name for, may be <code>null</code> * @return the package name or an empty string * @since 2.4 */ public static String getPackageCanonicalName(String canonicalName) { return ClassUtils.getPackageName(getCanonicalName(canonicalName)); } /** * <p>Converts a given name of class into canonical format. * If name of class is not a name of array class it returns * unchanged name.</p> * <p>Example: * <ul> * <li><code>getCanonicalName("[I") = "int[]"</code></li> * <li><code>getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"</code></li> * <li><code>getCanonicalName("java.lang.String") = "java.lang.String"</code></li> * </ul> * </p> * * @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; } else { int dim = 0; while (className.startsWith("[")) { dim++; className = className.substring(1); } if (dim < 1) { return className; } else { if (className.startsWith("L")) { className = className.substring(1, className.endsWith(";") ? className.length() - 1 : className.length()); } else { if (className.length() > 0) { className = reverseAbbreviationMap.get(className.substring(0, 1)); } } StringBuffer canonicalClassNameBuffer = new StringBuffer(className); for (int i = 0; i < dim; i++) { canonicalClassNameBuffer.append("[]"); } return canonicalClassNameBuffer.toString(); } } } }