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Ant example source code file (StringUtils.java)

This example Ant source code file (StringUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Ant tags/keywords

gigabyte, gigabyte, io, kilobyte, kilobyte, megabyte, petabyte, printwriter, string, string, stringbuffer, stringwriter, terabyte, util, vector, vector

The StringUtils.java source code

/*
 *  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.tools.ant.util;

import java.io.PrintWriter;
import java.io.StringWriter;
import java.util.Vector;

/**
 * A set of helper methods related to string manipulation.
 *
 */
public final class StringUtils {

    /**
     * constructor to stop anyone instantiating the class
     */
    private StringUtils() {
    }

    /** the line separator for this OS */
    public static final String LINE_SEP = System.getProperty("line.separator");

    /**
     * Splits up a string into a list of lines. It is equivalent
     * to <tt>split(data, '\n').
     * @param data the string to split up into lines.
     * @return the list of lines available in the string.
     */
    public static Vector lineSplit(String data) {
        return split(data, '\n');
    }

    /**
     * Splits up a string where elements are separated by a specific
     * character and return all elements.
     * @param data the string to split up.
     * @param ch the separator character.
     * @return the list of elements.
     */
    public static Vector split(String data, int ch) {
        Vector elems = new Vector();
        int pos = -1;
        int i = 0;
        while ((pos = data.indexOf(ch, i)) != -1) {
            String elem = data.substring(i, pos);
            elems.addElement(elem);
            i = pos + 1;
        }
        elems.addElement(data.substring(i));
        return elems;
    }

    /**
     * Replace occurrences into a string.
     * @param data the string to replace occurrences into
     * @param from the occurrence to replace.
     * @param to the occurrence to be used as a replacement.
     * @return the new string with replaced occurrences.
     */
    public static String replace(String data, String from, String to) {
        StringBuffer buf = new StringBuffer(data.length());
        int pos = -1;
        int i = 0;
        while ((pos = data.indexOf(from, i)) != -1) {
            buf.append(data.substring(i, pos)).append(to);
            i = pos + from.length();
        }
        buf.append(data.substring(i));
        return buf.toString();
    }

    /**
     * Convenient method to retrieve the full stacktrace from a given exception.
     * @param t the exception to get the stacktrace from.
     * @return the stacktrace from the given exception.
     */
    public static String getStackTrace(Throwable t) {
        StringWriter sw = new StringWriter();
        PrintWriter pw = new PrintWriter(sw, true);
        t.printStackTrace(pw);
        pw.flush();
        pw.close();
        return sw.toString();
    }

    /**
     * Checks that a string buffer ends up with a given string. It may sound
     * trivial with the existing
     * JDK API but the various implementation among JDKs can make those
     * methods extremely resource intensive
     * and perform poorly due to massive memory allocation and copying. See
     * @param buffer the buffer to perform the check on
     * @param suffix the suffix
     * @return  <code>true if the character sequence represented by the
     *          argument is a suffix of the character sequence represented by
     *          the StringBuffer object; <code>false otherwise. Note that the
     *          result will be <code>true if the argument is the
     *          empty string.
     */
    public static boolean endsWith(StringBuffer buffer, String suffix) {
        if (suffix.length() > buffer.length()) {
            return false;
        }
        // this loop is done on purpose to avoid memory allocation performance
        // problems on various JDKs
        // StringBuffer.lastIndexOf() was introduced in jdk 1.4 and
        // implementation is ok though does allocation/copying
        // StringBuffer.toString().endsWith() does massive memory
        // allocation/copying on JDK 1.5
        // See http://issues.apache.org/bugzilla/show_bug.cgi?id=37169
        int endIndex = suffix.length() - 1;
        int bufferIndex = buffer.length() - 1;
        while (endIndex >= 0) {
            if (buffer.charAt(bufferIndex) != suffix.charAt(endIndex)) {
                return false;
            }
            bufferIndex--;
            endIndex--;
        }
        return true;
    }

    /**
     * xml does not do "c" like interpretation of strings.
     * i.e. \n\r\t etc.
     * this method processes \n, \r, \t, \f, \\
     * also subs \s -> " \n\r\t\f"
     * a trailing '\' will be ignored
     *
     * @param input raw string with possible embedded '\'s
     * @return converted string
     * @since Ant 1.7
     */
    public static String resolveBackSlash(String input) {
        StringBuffer b = new StringBuffer();
        boolean backSlashSeen = false;
        for (int i = 0; i < input.length(); ++i) {
            char c = input.charAt(i);
            if (!backSlashSeen) {
                if (c == '\\') {
                    backSlashSeen = true;
                } else {
                    b.append(c);
                }
            } else {
                switch (c) {
                    case '\\':
                        b.append((char) '\\');
                        break;
                    case 'n':
                        b.append((char) '\n');
                        break;
                    case 'r':
                        b.append((char) '\r');
                        break;
                    case 't':
                        b.append((char) '\t');
                        break;
                    case 'f':
                        b.append((char) '\f');
                        break;
                    case 's':
                        b.append(" \t\n\r\f");
                        break;
                    default:
                        b.append(c);
                }
                backSlashSeen = false;
            }
        }
        return b.toString();
    }
    
    /**
     * Takes a human readable size representation eg 10K
     * a long value. Doesn't support 1.1K or other rational values.
     * @param humanSize
     * @return a long value representation
     * @throws Exception
     * @since Ant 1.7
     */
    public static long parseHumanSizes(String humanSize) throws Exception {
    	final long KILOBYTE = 1024;
    	final long MEGABYTE = KILOBYTE * 1024;
    	final long GIGABYTE = MEGABYTE * 1024;
    	final long TERABYTE = GIGABYTE * 1024;
    	final long PETABYTE = TERABYTE * 1024;
        //last character isn't a digit
    	if(!Character.isDigit(humanSize.charAt(humanSize.length()-1))) {
    		char c = humanSize.charAt(humanSize.length()-1);
    		long value = Long.valueOf(humanSize.substring(0, humanSize.length()-1)).longValue();
    		switch (c) {
    			case 'K':
    				return value * KILOBYTE;
    			case 'M':
    				return value * MEGABYTE;
    			case 'G':
    				return value * GIGABYTE;
    			case 'T':
    				return value * TERABYTE;
    			case 'P':
    				return value * PETABYTE;
    			default:
    				return value;
    		}
    	} else {
    	    return Long.parseLong(humanSize);
    	}
    }
}

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