com.dsj.core.beans.ObjectUtils.java Source code

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/*
 * Copyright 2002-2006 the original author or authors.
 *
 * 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.dsj.core.beans;

import java.lang.reflect.Array;
import java.util.Arrays;

/**
 * Miscellaneous object utility methods. Mainly for internal use within the
 * framework; consider Jakarta's Commons Lang for a more comprehensive suite of
 * object utilities.
 * 
 * @author Juergen Hoeller
 * @author Keith Donald
 * @author Rod Johnson
 * @author Rob Harrop
 * @author Alex Ruiz
 * @since 19.03.2004
 * @see org.apache.commons.lang.ObjectUtils
 */
public abstract class ObjectUtils {

    private static final int INITIAL_HASH = 7;
    private static final int MULTIPLIER = 31;

    private static final String EMPTY_STRING = "";
    private static final String NULL_STRING = "null";
    private static final String ARRAY_START = "{";
    private static final String ARRAY_END = "}";
    private static final String EMPTY_ARRAY = ARRAY_START + ARRAY_END;
    private static final String ARRAY_ELEMENT_SEPARATOR = ", ";

    /**
     * Return whether the given throwable is a checked exception: that is,
     * neither a RuntimeException nor an Error.
     * 
     * @param ex
     *            the throwable to check
     * @return whether the throwable is a checked exception
     * @see java.lang.Exception
     * @see java.lang.RuntimeException
     * @see java.lang.Error
     */
    public static boolean isCheckedException(Throwable ex) {
        return !(ex instanceof RuntimeException || ex instanceof Error);
    }

    /**
     * Check whether the given exception is compatible with the exceptions
     * declared in a throws clause.
     * 
     * @param ex
     *            the exception to checked
     * @param declaredExceptions
     *            the exceptions declared in the throws clause
     * @return whether the given exception is compatible
     */
    public static boolean isCompatibleWithThrowsClause(Throwable ex, Class[] declaredExceptions) {
        if (!isCheckedException(ex)) {
            return true;
        }
        if (declaredExceptions != null) {
            for (int i = 0; i < declaredExceptions.length; i++) {
                if (declaredExceptions[i].isAssignableFrom(ex.getClass())) {
                    return true;
                }
            }
        }
        return false;
    }

    /**
     * Return whether the given array is empty: that is, null or of zero length.
     * 
     * @param array
     *            the array to check
     */
    public static boolean isEmpty(Object[] array) {
        return (array == null || array.length == 0);
    }

    /**
     * Append the given Object to the given array, returning a new array
     * consisting of the input array contents plus the given Object.
     * 
     * @param array
     *            the array to append to (can be <code>null</code>)
     * @param obj
     *            the Object to append
     * @return the new array (of the same component type; never
     *         <code>null</code>)
     */
    public static Object[] addObjectToArray(Object[] array, Object obj) {
        Class compType = Object.class;
        if (array != null) {
            compType = array.getClass().getComponentType();
        } else if (obj != null) {
            compType = obj.getClass();
        }
        int newArrLength = (array != null ? array.length + 1 : 1);
        Object[] newArr = (Object[]) Array.newInstance(compType, newArrLength);
        if (array != null) {
            System.arraycopy(array, 0, newArr, 0, array.length);
        }
        newArr[newArr.length - 1] = obj;
        return newArr;
    }

    /**
     * Convert a primitive array to an object array of primitive wrapper
     * objects.
     * 
     * @param primitiveArray
     *            the primitive array
     * @return the object array
     * @throws IllegalArgumentException
     *             if the parameter is not a primitive array
     */
    public static Object[] toObjectArray(Object primitiveArray) {
        if (primitiveArray == null) {
            return new Object[0];
        }
        Class clazz = primitiveArray.getClass();
        if (!clazz.isArray() || !clazz.getComponentType().isPrimitive()) {
            throw new IllegalArgumentException("The specified parameter is not a primitive array");
        }
        int length = Array.getLength(primitiveArray);
        if (length == 0) {
            return new Object[0];
        }
        Class wrapperType = Array.get(primitiveArray, 0).getClass();
        Object[] newArray = (Object[]) Array.newInstance(wrapperType, length);
        for (int i = 0; i < length; i++) {
            newArray[i] = Array.get(primitiveArray, i);
        }
        return newArray;
    }

    // ---------------------------------------------------------------------
    // Convenience methods for content-based equality/hash-code handling
    // ---------------------------------------------------------------------

    /**
     * Determine if the given objects are equal, returning <code>true</code> if
     * both are <code>null</code> or <code>false</code> if only one is
     * <code>null</code>.
     * <p>
     * Compares arrays with <code>Arrays.equals</code>, performing an equality
     * check based on the array elements rather than the array reference.
     * 
     * @param o1
     *            first Object to compare
     * @param o2
     *            second Object to compare
     * @return whether the given objects are equal
     * @see java.util.Arrays#equals
     */
    public static boolean nullSafeEquals(Object o1, Object o2) {
        if (o1 == o2) {
            return true;
        }
        if (o1 == null || o2 == null) {
            return false;
        }
        if (o1.equals(o2)) {
            return true;
        }
        if (o1 instanceof Object[] && o2 instanceof Object[]) {
            return Arrays.equals((Object[]) o1, (Object[]) o2);
        }
        if (o1 instanceof boolean[] && o2 instanceof boolean[]) {
            return Arrays.equals((boolean[]) o1, (boolean[]) o2);
        }
        if (o1 instanceof byte[] && o2 instanceof byte[]) {
            return Arrays.equals((byte[]) o1, (byte[]) o2);
        }
        if (o1 instanceof char[] && o2 instanceof char[]) {
            return Arrays.equals((char[]) o1, (char[]) o2);
        }
        if (o1 instanceof double[] && o2 instanceof double[]) {
            return Arrays.equals((double[]) o1, (double[]) o2);
        }
        if (o1 instanceof float[] && o2 instanceof float[]) {
            return Arrays.equals((float[]) o1, (float[]) o2);
        }
        if (o1 instanceof int[] && o2 instanceof int[]) {
            return Arrays.equals((int[]) o1, (int[]) o2);
        }
        if (o1 instanceof long[] && o2 instanceof long[]) {
            return Arrays.equals((long[]) o1, (long[]) o2);
        }
        if (o1 instanceof short[] && o2 instanceof short[]) {
            return Arrays.equals((short[]) o1, (short[]) o2);
        }
        return false;
    }

    /**
     * Return as hash code for the given object; typically the value of
     * <code>{@link Object#hashCode()}</code>. If the object is an array, this
     * method will delegate to any of the <code>nullSafeHashCode</code> methods
     * for arrays in this class. If the object is <code>null</code>, this method
     * returns 0.
     * 
     * @see #nullSafeHashCode(Object[])
     * @see #nullSafeHashCode(boolean[])
     * @see #nullSafeHashCode(byte[])
     * @see #nullSafeHashCode(char[])
     * @see #nullSafeHashCode(double[])
     * @see #nullSafeHashCode(float[])
     * @see #nullSafeHashCode(int[])
     * @see #nullSafeHashCode(long[])
     * @see #nullSafeHashCode(short[])
     */
    public static int nullSafeHashCode(Object obj) {
        if (obj == null) {
            return 0;
        }
        if (obj instanceof Object[]) {
            return nullSafeHashCode((Object[]) obj);
        }
        if (obj instanceof boolean[]) {
            return nullSafeHashCode((boolean[]) obj);
        }
        if (obj instanceof byte[]) {
            return nullSafeHashCode((byte[]) obj);
        }
        if (obj instanceof char[]) {
            return nullSafeHashCode((char[]) obj);
        }
        if (obj instanceof double[]) {
            return nullSafeHashCode((double[]) obj);
        }
        if (obj instanceof float[]) {
            return nullSafeHashCode((float[]) obj);
        }
        if (obj instanceof int[]) {
            return nullSafeHashCode((int[]) obj);
        }
        if (obj instanceof long[]) {
            return nullSafeHashCode((long[]) obj);
        }
        if (obj instanceof short[]) {
            return nullSafeHashCode((short[]) obj);
        }
        return obj.hashCode();
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(Object[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + nullSafeHashCode(array[i]);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(boolean[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + hashCode(array[i]);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(byte[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(char[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(double[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + hashCode(array[i]);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(float[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + hashCode(array[i]);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(int[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(long[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + hashCode(array[i]);
        }
        return hash;
    }

    /**
     * Return a hash code based on the contents of the specified array. If
     * <code>array</code> is <code>null</code>, this method returns 0.
     */
    public static int nullSafeHashCode(short[] array) {
        if (array == null) {
            return 0;
        }
        int hash = INITIAL_HASH;
        int arraySize = array.length;
        for (int i = 0; i < arraySize; i++) {
            hash = MULTIPLIER * hash + array[i];
        }
        return hash;
    }

    /**
     * Return the same value as <code>{@link Boolean#hashCode()}</code>.
     * 
     * @see Boolean#hashCode()
     */
    public static int hashCode(boolean bool) {
        return bool ? 1231 : 1237;
    }

    /**
     * Return the same value as <code>{@link Double#hashCode()}</code>.
     * 
     * @see Double#hashCode()
     */
    public static int hashCode(double dbl) {
        long bits = Double.doubleToLongBits(dbl);
        return hashCode(bits);
    }

    /**
     * Return the same value as <code>{@link Float#hashCode()}</code>.
     * 
     * @see Float#hashCode()
     */
    public static int hashCode(float flt) {
        return Float.floatToIntBits(flt);
    }

    /**
     * Return the same value as <code>{@link Long#hashCode()}</code>.
     * 
     * @see Long#hashCode()
     */
    public static int hashCode(long lng) {
        return (int) (lng ^ (lng >>> 32));
    }

    // ---------------------------------------------------------------------
    // Convenience methods for content-based toString output
    // ---------------------------------------------------------------------

    /**
     * Return a String representation of the specified Object.
     * <p>
     * Returns {@link #NULL_STRING the String 'null'} if <code>obj</code> is
     * <code>null</code>.
     * 
     * @param obj
     *            the object whose String representation to return
     * @return a String representation of <code>obj</code>
     */
    public static String nullSafeToString(Object obj) {
        if (obj == null) {
            return NULL_STRING;
        }
        if (obj instanceof String) {
            return (String) obj;
        }
        if (obj instanceof Object[]) {
            return nullSafeToString((Object[]) obj);
        }
        if (obj instanceof boolean[]) {
            return nullSafeToString((boolean[]) obj);
        }
        if (obj instanceof byte[]) {
            return nullSafeToString((byte[]) obj);
        }
        if (obj instanceof char[]) {
            return nullSafeToString((char[]) obj);
        }
        if (obj instanceof double[]) {
            return nullSafeToString((double[]) obj);
        }
        if (obj instanceof float[]) {
            return nullSafeToString((float[]) obj);
        }
        if (obj instanceof int[]) {
            return nullSafeToString((int[]) obj);
        }
        if (obj instanceof long[]) {
            return nullSafeToString((long[]) obj);
        }
        if (obj instanceof short[]) {
            return nullSafeToString((short[]) obj);
        }
        return obj.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(Object[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append(String.valueOf(array[i]));
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(boolean[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }

            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(byte[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(char[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append("'" + array[i] + "'");
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(double[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }

            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(float[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }

            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(int[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(long[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of the contents of the specified array.
     * The String representation consists of a list of the array's elements,
     * enclosed in curly braces (<code>"{}"</code>). Adjacent elements are
     * separated by the characters <code>", "</code> (a comma followed by a
     * space). Returns <code>"null"</code> if <code>array</code> is
     * <code>null</code>.
     * 
     * @param array
     *            the array whose String representation to return
     * @return a String representation of <code>array</code>
     */
    public static String nullSafeToString(short[] array) {
        if (array == null) {
            return NULL_STRING;
        }
        int length = array.length;
        if (length == 0) {
            return EMPTY_ARRAY;
        }
        StringBuffer buffer = new StringBuffer();
        for (int i = 0; i < length; i++) {
            if (i == 0) {
                buffer.append(ARRAY_START);
            } else {
                buffer.append(ARRAY_ELEMENT_SEPARATOR);
            }
            buffer.append(array[i]);
        }
        buffer.append(ARRAY_END);
        return buffer.toString();
    }

    /**
     * Return a String representation of an object's overall identity.
     * 
     * @param obj
     *            the object (may be <code>null</code>)
     * @return the object's identity as String representation, or
     *         <code>null</code> if the object was <code>null</code>
     */
    public static String identityToString(Object obj) {
        if (obj == null) {
            return EMPTY_STRING;
        }
        return obj.getClass().getName() + "@" + getIdentityHexString(obj);
    }

    /**
     * Return a hex String form of an object's identity hash code.
     * 
     * @param obj
     *            the object
     * @return the object's identity code in hex notation
     */
    public static String getIdentityHexString(Object obj) {
        return Integer.toHexString(System.identityHashCode(obj));
    }

    /**
     * Return a content-based String representation if <code>obj</code> is not
     * <code>null</code>; otherwise returns an empty <code>String</code>.
     * <p>
     * Differs from <code>nullSafeToString</code> in that it returns an empty
     * String rather than "null" for a <code>null</code> value.
     * 
     * @see #nullSafeToString(Object)
     */
    public static String getDisplayString(Object obj) {
        if (obj == null) {
            return EMPTY_STRING;
        }
        return nullSafeToString(obj);
    }

}