Java Array to String deepToString(Object[] a)

Description

Returns a string representation of the "deep contents" of the specified array.

License

Apache License

Parameter

Parameter	Description
a	the array whose string representation to return

Return

a string representation of a

Declaration

public static String deepToString(Object[] a) 

Method Source Code

//package com.java2s;
/*//from   www  . j a  va2  s  .  c  o m
 * Copyright 2016 xueyi (1581249005@qq.com)
 *
 * The Smart-Actor Project 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 java.util.*;

public class Main {
    /**
     * Returns a string representation of the "deep contents" of the specified
     * array.  If the array contains other arrays as elements, the string
     * representation contains their contents and so on.  This method is
     * designed for converting multidimensional arrays to strings.
     *
     * <p>The string representation consists of a list of the array's
     * elements, enclosed in square brackets (<tt>"[]"</tt>).  Adjacent
     * elements are separated by the characters <tt>", "</tt> (a comma
     * followed by a space).  Elements are converted to strings as by
     * <tt>String.valueOf(Object)</tt>, unless they are themselves
     * arrays.
     *
     * <p>If an element <tt>e</tt> is an array of a primitive type, it is
     * converted to a string as by invoking the appropriate overloading of
     * <tt>Arrays.toString(e)</tt>.  If an element <tt>e</tt> is an array of a
     * reference type, it is converted to a string as by invoking
     * this method recursively.
     *
     * <p>To avoid infinite recursion, if the specified array contains itself
     * as an element, or contains an indirect reference to itself through one
     * or more levels of arrays, the self-reference is converted to the string
     * <tt>"[...]"</tt>.  For example, an array containing only a reference
     * to itself would be rendered as <tt>"[[...]]"</tt>.
     *
     * <p>This method returns <tt>"null"</tt> if the specified array
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @see #toString(Object[])
     * @since 1.5
     */
    public static String deepToString(Object[] a) {
        if (a == null)
            return "null";

        int bufLen = 20 * a.length;
        if (a.length != 0 && bufLen <= 0)
            bufLen = Integer.MAX_VALUE;
        StringBuilder buf = new StringBuilder(bufLen);
        deepToString(a, buf, new HashSet<Object[]>());
        return buf.toString();
    }

    private static void deepToString(Object[] a, StringBuilder buf, Set<Object[]> dejaVu) {
        if (a == null) {
            buf.append("null");
            return;
        }
        int iMax = a.length - 1;
        if (iMax == -1) {
            buf.append("[]");
            return;
        }

        dejaVu.add(a);
        buf.append('[');
        for (int i = 0;; i++) {

            Object element = a[i];
            if (element == null) {
                buf.append("null");
            } else {
                Class eClass = element.getClass();

                if (eClass.isArray()) {
                    if (eClass == byte[].class)
                        buf.append(toString((byte[]) element));
                    else if (eClass == short[].class)
                        buf.append(toString((short[]) element));
                    else if (eClass == int[].class)
                        buf.append(toString((int[]) element));
                    else if (eClass == long[].class)
                        buf.append(toString((long[]) element));
                    else if (eClass == char[].class)
                        buf.append(toString((char[]) element));
                    else if (eClass == float[].class)
                        buf.append(toString((float[]) element));
                    else if (eClass == double[].class)
                        buf.append(toString((double[]) element));
                    else if (eClass == boolean[].class)
                        buf.append(toString((boolean[]) element));
                    else { // element is an array of object references
                        if (dejaVu.contains(element))
                            buf.append("[...]");
                        else
                            deepToString((Object[]) element, buf, dejaVu);
                    }
                } else { // element is non-null and not an array
                    buf.append(element.toString());
                }
            }
            if (i == iMax)
                break;
            buf.append(", ");
        }
        buf.append(']');
        dejaVu.remove(a);
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(long)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt>
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(long[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(int)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt> is
     * <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(int[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(short)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt>
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(short[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(char)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt>
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(char[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements
     * are separated by the characters <tt>", "</tt> (a comma followed
     * by a space).  Elements are converted to strings as by
     * <tt>String.valueOf(byte)</tt>.  Returns <tt>"null"</tt> if
     * <tt>a</tt> is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(byte[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(boolean)</tt>.  Returns <tt>"null"</tt> if
     * <tt>a</tt> is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(boolean[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(float)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt>
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(float[] a) {
        if (a == null)
            return "null";

        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * The string representation consists of a list of the array's elements,
     * enclosed in square brackets (<tt>"[]"</tt>).  Adjacent elements are
     * separated by the characters <tt>", "</tt> (a comma followed by a
     * space).  Elements are converted to strings as by
     * <tt>String.valueOf(double)</tt>.  Returns <tt>"null"</tt> if <tt>a</tt>
     * is <tt>null</tt>.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @since 1.5
     */
    public static String toString(double[] a) {
        if (a == null)
            return "null";
        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(a[i]);
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }

    /**
     * Returns a string representation of the contents of the specified array.
     * If the array contains other arrays as elements, they are converted to
     * strings by the {@link Object#toString} method inherited from
     * <tt>Object</tt>, which describes their <i>identities</i> rather than
     * their contents.
     *
     * <p>The value returned by this method is equal to the value that would
     * be returned by <tt>Arrays.asList(a).toString()</tt>, unless <tt>a</tt>
     * is <tt>null</tt>, in which case <tt>"null"</tt> is returned.
     *
     * @param a the array whose string representation to return
     * @return a string representation of <tt>a</tt>
     * @see #deepToString(Object[])
     * @since 1.5
     */
    public static String toString(Object[] a) {
        if (a == null)
            return "null";

        int iMax = a.length - 1;
        if (iMax == -1)
            return "[]";

        StringBuilder b = new StringBuilder();
        b.append('[');
        for (int i = 0;; i++) {
            b.append(String.valueOf(a[i]));
            if (i == iMax)
                return b.append(']').toString();
            b.append(", ");
        }
    }
}

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