Replace all occurrences of a key by a value in StringBuilder - Java java.lang

Java examples for java.lang:StringBuilder

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Description

Replace all occurrences of a key by a value in StringBuilder

Demo Code

/*  Copyright 2011 Alexander Bunkenburg alex@inspiracio.com

    This file is part of atom.jar./*from  w ww . ja v  a2 s . co m*/

    atom.jar is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    atom.jar is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with atom.jar.  If not, see <http://www.gnu.org/licenses/>.
 */
//package com.java2s;

public class Main {
    public static void main(String[] argv) throws Exception {
        StringBuilder builder = new StringBuilder();
        String key = "java2s.com";
        String value = "java2s.com";
        System.out.println(replaceAll(builder, key, value));
    }

    /** Replace all occurrences of a key by a value. 
     * @param builder Will change this builder.
     * @param key The string to look for in the builder.
     *    This is just a String. not a regular expression.
     * @param value The string that goes in the builder
     * @return How many replacements has the method made? */
    public static int replaceAll(StringBuilder builder, String key,
            String value) {
        //Is there a better way to do this?
        int count = 0;
        int i = 0;
        while (0 <= i && i < builder.length()) {
            //find next occurrence
            i = builder.indexOf(key, i);
            if (0 <= i) {
                //substitute one occurrence
                int end = i + key.length();
                builder.replace(i, end, value);
                count++;
                //and prepare for the next
                i = end;
            }
        }
        return count;
    }

    /** Replace all occurrences of a key-char by a value-char.
     * Having a separate method for char-replacement is good
     * for performance, because we know that the builder needn't
     * grow and we will not shift chars.
     * @param builder Will change this builder.
     * @param key The char to look for in the builder.
     * @param value The char that goes in the builder 
     * */
    public static void replaceAll(StringBuilder builder, char key,
            char value) {
        final int N = builder.length();
        for (int i = 0; i < N; i++) {
            char c = builder.charAt(i);
            if (c == key) {
                builder.setCharAt(i, value);
            }
        }
    }
}

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