Java tutorial
package objenome.util; /** * Created by me on 5/6/15. */ /* * 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. */ import org.apache.commons.lang3.ArrayUtils; import org.apache.commons.lang3.JavaVersion; import org.apache.commons.lang3.StringUtils; import org.apache.commons.lang3.SystemUtils; import org.apache.commons.lang3.mutable.MutableObject; import java.lang.reflect.Method; import java.lang.reflect.Modifier; import java.util.*; /** * <p>Operates on classes without using reflection.</p> * * <p>This class handles invalid {@code null} inputs as best it can. * Each method documents its behaviour in more detail.</p> * * <p>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}. </p> * * @since 2.0 */ public enum ClassUtils { ; /** * Inclusivity literals for {@link #hierarchy(Class, Interfaces)}. * @since 3.2 */ public enum Interfaces { INCLUDE, EXCLUDE } /** * The package separator character: <code>'.' == {@value}</code>. */ public static final char PACKAGE_SEPARATOR_CHAR = '.'; /** * The package separator String: <code>"."</code>. */ public static final String PACKAGE_SEPARATOR = String.valueOf(PACKAGE_SEPARATOR_CHAR); /** * The inner class separator character: <code>'$' == {@value}</code>. */ public static final char INNER_CLASS_SEPARATOR_CHAR = '$'; /** * The inner class separator String: {@code "$"}. */ public static final String INNER_CLASS_SEPARATOR = String.valueOf(INNER_CLASS_SEPARATOR_CHAR); /** * Maps primitive {@code Class}es to their corresponding wrapper {@code Class}. */ private static final Map<Class<?>, Class<?>> primitiveWrapperMap = new HashMap<>(); static { primitiveWrapperMap.put(Boolean.TYPE, Boolean.class); primitiveWrapperMap.put(Byte.TYPE, Byte.class); primitiveWrapperMap.put(Character.TYPE, Character.class); primitiveWrapperMap.put(Short.TYPE, Short.class); primitiveWrapperMap.put(Integer.TYPE, Integer.class); primitiveWrapperMap.put(Long.TYPE, Long.class); primitiveWrapperMap.put(Double.TYPE, Double.class); primitiveWrapperMap.put(Float.TYPE, Float.class); primitiveWrapperMap.put(Void.TYPE, Void.TYPE); } /** * Maps wrapper {@code Class}es to their corresponding primitive types. */ private static final Map<Class<?>, Class<?>> wrapperPrimitiveMap = new HashMap<>(); static { for (Map.Entry<Class<?>, Class<?>> entry : primitiveWrapperMap.entrySet()) { Class<?> primitiveClass = entry.getKey(); Class<?> wrapperClass = entry.getValue(); if (!primitiveClass.equals(wrapperClass)) { wrapperPrimitiveMap.put(wrapperClass, primitiveClass); } } } /** * Maps a primitive class name to its corresponding abbreviation used in array class names. */ private static final Map<String, String> abbreviationMap; /** * Maps an abbreviation used in array class names to corresponding primitive class name. */ private static final Map<String, String> reverseAbbreviationMap; /** * Feed abbreviation maps */ static { Map<String, String> m = new HashMap<>(); m.put("int", "I"); m.put("boolean", "Z"); m.put("float", "F"); m.put("long", "J"); m.put("short", "S"); m.put("byte", "B"); m.put("double", "D"); m.put("char", "C"); m.put("void", "V"); Map<String, String> r = new HashMap<>(); for (Map.Entry<String, String> e : m.entrySet()) { r.put(e.getValue(), e.getKey()); } abbreviationMap = Collections.unmodifiableMap(m); reverseAbbreviationMap = Collections.unmodifiableMap(r); } // Short class name // ---------------------------------------------------------------------- /** * <p>Gets the class name minus the package name for an {@code Object}.</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}.</p> * * <p>Consider using the Java 5 API {@link Class#getSimpleName()} instead. * The one known difference is that this code will return {@code "Map.Entry"} while * the {@code java.lang.Class} variant will simply return {@code "Entry"}. </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> * <p>Note that this method differs from Class.getSimpleName() in that this will * return {@code "Map.Entry"} whilst the {@code java.lang.Class} variant will simply * return {@code "Entry"}. </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 (StringUtils.isEmpty(className)) { return StringUtils.EMPTY; } StringBuilder arrayPrefix = new StringBuilder(); // Handle array encoding if (className.length() > 0 && className.charAt(0) == '[') { 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; } /** * <p>Null-safe version of <code>aClass.getSimpleName()</code></p> * * @param cls the class for which to get the simple name. * @return the simple class name. * @since 3.0 * @see Class#getSimpleName() */ public static String getSimpleName(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return cls.getSimpleName(); } /** * <p>Null-safe version of <code>aClass.getSimpleName()</code></p> * * @param object the object for which to get the simple class name. * @param valueIfNull the value to return if <code>object</code> is <code>null</code> * @return the simple class name. * @since 3.0 * @see Class#getSimpleName() */ public static String getSimpleName(Object object, String valueIfNull) { if (object == null) { return valueIfNull; } return getSimpleName(object.getClass()); } // Package name // ---------------------------------------------------------------------- /** * <p>Gets the package name of an {@code Object}.</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}.</p> * * @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(Class<?> cls) { if (cls == null) { return StringUtils.EMPTY; } return getPackageName(cls.getName()); } /** * <p>Gets the package name from a {@code String}.</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} * @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); } int i = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (i == -1) { return StringUtils.EMPTY; } return className.substring(0, i); } // Abbreviated name // ---------------------------------------------------------------------- /** * <p>Gets the abbreviated name of a {@code Class}.</p> * * @param cls the class to get the abbreviated name for, may be {@code null} * @param len 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(Class<?> cls, int len) { if (cls == null) { return StringUtils.EMPTY; } return getAbbreviatedName(cls.getName(), len); } /** * <p>Gets the abbreviated class name from a {@code String}.</p> * * <p>The string passed in is assumed to be a class name - it is not checked.</p> * * <p>The abbreviation algorithm will shorten the class name, usually without * significant loss of meaning.</p> * <p>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.</p> * * <p>The following table illustrates the algorithm:</p> * <table summary="abbreviation examples"> * <tr><td>className</td><td>len</td><td>return</td></tr> * <tr><td> null</td><td> 1</td><td>""</td></tr> * <tr><td>"java.lang.String"</td><td> 5</td><td>"j.l.String"</td></tr> * <tr><td>"java.lang.String"</td><td>15</td><td>"j.lang.String"</td></tr> * <tr><td>"java.lang.String"</td><td>30</td><td>"java.lang.String"</td></tr> * </table> * @param className the className to get the abbreviated name for, may be {@code null} * @param len the desired length of the abbreviated name * @return the abbreviated name or an empty string * @throws IllegalArgumentException if len <= 0 * @since 3.4 */ public static String getAbbreviatedName(String className, int len) { if (len <= 0) { throw new IllegalArgumentException("len must be > 0"); } if (className == null) { return StringUtils.EMPTY; } int availableSpace = len; int packageLevels = StringUtils.countMatches(className, '.'); String[] output = new String[packageLevels + 1]; int endIndex = className.length() - 1; for (int level = packageLevels; level >= 0; level--) { int startIndex = className.lastIndexOf('.', endIndex); String part = className.substring(startIndex + 1, endIndex + 1); availableSpace -= part.length(); if (level > 0) { // all elements except top level require an additional char space availableSpace--; } if (level == packageLevels) { // ClassName is always complete output[level] = part; } else { output[level] = availableSpace > 0 ? part : part.substring(0, 1); } endIndex = startIndex - 1; } return StringUtils.join(output, '.'); } // Superclasses/Superinterfaces // ---------------------------------------------------------------------- /** * <p>Gets a {@code List} of superclasses for the given class.</p> * * @param cls the class to look up, may be {@code null} * @return the {@code List} of superclasses in order going up from this one * {@code null} if null input */ public static List<Class<?>> getAllSuperclasses(Class<?> cls) { if (cls == null) { return null; } List<Class<?>> classes = new ArrayList<>(); Class<?> superclass = cls.getSuperclass(); while (superclass != null) { classes.add(superclass); superclass = superclass.getSuperclass(); } return classes; } /** * <p>Gets a {@code List} 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} * @return the {@code List} of interfaces in order, * {@code null} if null input */ public static List<Class<?>> getAllInterfaces(Class<?> cls) { if (cls == null) { return null; } LinkedHashSet<Class<?>> interfacesFound = new LinkedHashSet<>(); getAllInterfaces(cls, interfacesFound); return new ArrayList<>(interfacesFound); } /** * Get the interfaces for the specified class. * * @param cls the class to look up, may be {@code null} * @param interfacesFound the {@code Set} of interfaces for the class */ private static void getAllInterfaces(Class<?> cls, 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} of class names, this method converts them into classes.</p> * * <p>A new {@code List} is returned. If the class name cannot be found, {@code null} * is stored in the {@code List}. If the class name in the {@code List} is * {@code null}, {@code null} is stored in the output {@code List}.</p> * * @param classNames the classNames to change * @return a {@code List} of Class objects corresponding to the class names, * {@code null} if null input * @throws ClassCastException if classNames contains a non String entry */ public static List<Class<?>> convertClassNamesToClasses(List<String> classNames) { if (classNames == null) { return null; } List<Class<?>> classes = new ArrayList<>(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} of {@code Class} objects, this method converts * them into class names.</p> * * <p>A new {@code List} is returned. {@code null} objects will be copied into * the returned list as {@code null}.</p> * * @param classes the classes to change * @return a {@code List} of class names corresponding to the Class objects, * {@code null} if null input * @throws ClassCastException if {@code classes} contains a non-{@code Class} entry */ public static List<String> convertClassesToClassNames(List<Class<?>> classes) { if (classes == null) { return null; } List<String> classNames = new ArrayList<>(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(Class)} method, this * method takes into account widenings of primitive classes and * {@code null}s.</p> * * <p>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.</p> * * <p>{@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.</p> * * <p>Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://docs.oracle.com/javase/specs/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * <p><strong>Since Lang 3.0,</strong> this method will default behavior for * calculating assignability between primitive and wrapper types <em>corresponding * to the running Java version</em>; i.e. autoboxing will be the default * behavior in VMs running Java versions > 1.5.</p> * * @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(Class<?>[] classArray, Class<?>... toClassArray) { return isAssignable(classArray, toClassArray, SystemUtils.isJavaVersionAtLeast(JavaVersion.JAVA_1_5)); } /** * <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(Class)} method, this * method takes into account widenings of primitive classes and * {@code null}s.</p> * * <p>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.</p> * * <p>{@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.</p> * * <p>Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://docs.oracle.com/javase/specs/">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} * @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, boolean autoboxing) { if (!ArrayUtils.isSameLength(classArray, toClassArray)) { return false; } if (classArray == null) { classArray = ArrayUtils.EMPTY_CLASS_ARRAY; } if (toClassArray == null) { toClassArray = ArrayUtils.EMPTY_CLASS_ARRAY; } for (int i = 0; i < classArray.length; i++) { if (!isAssignable(classArray[i], toClassArray[i], autoboxing)) { return false; } } return true; } /** * Returns whether the given {@code type} is a primitive or primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, * {@link Short}, {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * * @param type * The class to query or null. * @return true if the given {@code type} is a primitive or primitive wrapper ({@link Boolean}, {@link Byte}, {@link Character}, * {@link Short}, {@link Integer}, {@link Long}, {@link Double}, {@link Float}). * @since 3.1 */ public static boolean isPrimitiveOrWrapper(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(Class<?> type) { return wrapperPrimitiveMap.containsKey(type); } /** * <p>Checks if one {@code Class} can be assigned to a variable of * another {@code Class}.</p> * * <p>Unlike the {@link Class#isAssignableFrom(Class)} method, * this method takes into account widenings of primitive classes and * {@code null}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} 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.</p> * * <p>Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://docs.oracle.com/javase/specs/">The Java Language Specification</a></em>, * sections 5.1.1, 5.1.2 and 5.1.4 for details.</p> * * <p><strong>Since Lang 3.0,</strong> this method will default behavior for * calculating assignability between primitive and wrapper types <em>corresponding * to the running Java version</em>; i.e. autoboxing will be the default * behavior in VMs running Java versions > 1.5.</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} if assignment possible */ public static boolean isAssignable(Class<?> cls, Class<?> toClass) { return isAssignable(cls, toClass, SystemUtils.isJavaVersionAtLeast(JavaVersion.JAVA_1_5)); } /** * <p>Checks if one {@code Class} can be assigned to a variable of * another {@code Class}.</p> * * <p>Unlike the {@link Class#isAssignableFrom(Class)} method, * this method takes into account widenings of primitive classes and * {@code null}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} 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.</p> * * <p>Specifically, this method tests whether the type represented by the * specified {@code Class} parameter can be converted to the type * represented by this {@code Class} object via an identity conversion * widening primitive or widening reference conversion. See * <em><a href="http://docs.oracle.com/javase/specs/">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} 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()) { 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}, * returning {@code Void.TYPE}.</p> * * @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(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} 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()}. * 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 * <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} 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()} 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} 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} if the class is an inner or static nested class, * false if not or {@code null} */ public static boolean isInnerClass(Class<?> cls) { return cls != null && cls.getEnclosingClass() != null; } // Class loading // ---------------------------------------------------------------------- /** * Returns the class represented by {@code className} using the * {@code classLoader}. This implementation supports the syntaxes * "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", * "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}". * * @param classLoader the class loader to use to load the class * @param className the class name * @param initialize whether the class must be initialized * @return the class represented by {@code className} using the {@code classLoader} * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(ClassLoader classLoader, String className, boolean initialize) throws ClassNotFoundException { try { Class<?> clazz; if (abbreviationMap.containsKey(className)) { String clsName = '[' + abbreviationMap.get(className); clazz = Class.forName(clsName, initialize, classLoader).getComponentType(); } else { clazz = Class.forName(toCanonicalName(className), initialize, classLoader); } return clazz; } catch (ClassNotFoundException ex) { // allow path separators (.) as inner class name separators int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR); if (lastDotIndex != -1) { try { return getClass(classLoader, className.substring(0, lastDotIndex) + INNER_CLASS_SEPARATOR_CHAR + className.substring(lastDotIndex + 1), initialize); } catch (ClassNotFoundException ex2) { // NOPMD // ignore exception } } throw ex; } } /** * Returns the (initialized) class represented by {@code className} * using the {@code classLoader}. This implementation supports * the syntaxes "{@code java.util.Map.Entry[]}", * "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", * and "{@code [Ljava.util.Map$Entry;}". * * @param classLoader the class loader to use to load the class * @param className the class name * @return the class represented by {@code className} using the {@code classLoader} * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(ClassLoader classLoader, String className) throws ClassNotFoundException { return getClass(classLoader, className, true); } /** * Returns the (initialized) class represented by {@code className} * using the current thread's context class loader. This implementation * supports the syntaxes "{@code java.util.Map.Entry[]}", * "{@code java.util.Map$Entry[]}", "{@code [Ljava.util.Map.Entry;}", * and "{@code [Ljava.util.Map$Entry;}". * * @param className the class name * @return the class represented by {@code className} using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(String className) throws ClassNotFoundException { return getClass(className, true); } /** * Returns the class represented by {@code className} using the * current thread's context class loader. This implementation supports the * syntaxes "{@code java.util.Map.Entry[]}", "{@code java.util.Map$Entry[]}", * "{@code [Ljava.util.Map.Entry;}", and "{@code [Ljava.util.Map$Entry;}". * * @param className the class name * @param initialize whether the class must be initialized * @return the class represented by {@code className} using the current thread's context class loader * @throws ClassNotFoundException if the class is not found */ public static Class<?> getClass(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}, 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>).</p> * * <pre> * <code>Set set = Collections.unmodifiableSet(...); * Method method = ClassUtils.getPublicMethod(set.getClass(), "isEmpty", new Class[0]); * Object result = method.invoke(set, new Object[]);</code> * </pre> * * @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(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<>(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."); } if (className.endsWith("[]")) { StringBuilder classNameBuffer = new StringBuilder(); 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} in to an array of {@code Class} objects. * If any of these objects is null, a null element will be inserted into the array.</p> * * <p>This method returns {@code null} for a {@code null} input array.</p> * * @param array an {@code Object} array * @return a {@code Class} array, {@code null} if null array input * @since 2.4 */ public static Class<?>[] toClass(Object... array) { if (array == null) { return null; } 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] == null ? null : array[i].getClass(); } return classes; } // Short canonical name // ---------------------------------------------------------------------- /** * <p>Gets the canonical name minus the package name for an {@code Object}.</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}.</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}.</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}.</p> * * @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(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} * @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[]"}</li> * <li>{@code getCanonicalName("[Ljava.lang.String;") = "java.lang.String[]"}</li> * <li>{@code getCanonicalName("java.lang.String") = "java.lang.String"}</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; } int dim = 0; while (className.length() > 0 && className.charAt(0) == '[') { dim++; className = className.substring(1); } if (dim < 1) { return className; } if (className.length() > 0 && className.charAt(0) == 'L') { className = className.substring(1, className.length() > 0 && className.charAt(className.length() - 1) == ';' ? className.length() - 1 : className.length()); } else { if (!className.isEmpty()) { className = reverseAbbreviationMap.get(className.substring(0, 1)); } } StringBuilder canonicalClassNameBuffer = new StringBuilder(className); for (int i = 0; i < dim; i++) { canonicalClassNameBuffer.append("[]"); } return canonicalClassNameBuffer.toString(); } /** * Get 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<Class<?>> hierarchy(Class<?> type) { return hierarchy(type, Interfaces.EXCLUDE); } /** * Get 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<Class<?>> hierarchy(Class<?> type, Interfaces interfacesBehavior) { Iterable<Class<?>> classes = () -> { MutableObject<Class<?>> next = new MutableObject<>(type); return new Iterator<Class<?>>() { @Override public boolean hasNext() { return next.getValue() != null; } @Override public Class<?> next() { Class<?> result = next.getValue(); next.setValue(result.getSuperclass()); return result; } @Override public void remove() { throw new UnsupportedOperationException(); } }; }; if (interfacesBehavior != Interfaces.INCLUDE) { return classes; } return () -> { Set<Class<?>> seenInterfaces = new HashSet<>(); Iterator<Class<?>> wrapped = classes.iterator(); return new Iterator<Class<?>>() { Iterator<Class<?>> interfaces = Collections.<Class<?>>emptySet().iterator(); @Override public boolean hasNext() { return interfaces.hasNext() || wrapped.hasNext(); } @Override public Class<?> next() { if (interfaces.hasNext()) { Class<?> nextInterface = interfaces.next(); seenInterfaces.add(nextInterface); return nextInterface; } Class<?> nextSuperclass = wrapped.next(); Set<Class<?>> currentInterfaces = new LinkedHashSet<>(); walkInterfaces(currentInterfaces, nextSuperclass); interfaces = currentInterfaces.iterator(); return nextSuperclass; } private void walkInterfaces(Set<Class<?>> addTo, Class<?> c) { for (Class<?> iface : c.getInterfaces()) { if (!seenInterfaces.contains(iface)) { addTo.add(iface); } walkInterfaces(addTo, iface); } } @Override public void remove() { throw new UnsupportedOperationException(); } }; }; } }