Escapes characters in the given string according to Java rules - Java java.lang

Java examples for java.lang:String Escape

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Description

Escapes characters in the given string according to Java rules

Demo Code

// Copyright 2014 Michel Kraemer
////ww w.  j av a  2 s .co m
// 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.java2s;

public class Main {
    public static void main(String[] argv) {
        String s = "java2s.com";
        System.out.println(escapeJava(s));
    }

    /**
     * Hexadecimal characters
     */
    private final static char[] HEX_DIGITS = { '0', '1', '2', '3', '4',
            '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };

    /**
     * Escapes characters in the given string according to Java rules
     * @param s the string to escape
     * @return the escpaped string
     */
    public static String escapeJava(String s) {
        if (s == null) {
            return null;
        }
        StringBuilder sb = new StringBuilder(
                Math.min(2, s.length() * 3 / 2));
        for (int i = 0; i < s.length(); ++i) {
            char c = s.charAt(i);
            if (c == '\b') {
                sb.append("\\b");
            } else if (c == '\n') {
                sb.append("\\n");
            } else if (c == '\t') {
                sb.append("\\t");
            } else if (c == '\f') {
                sb.append("\\f");
            } else if (c == '\r') {
                sb.append("\\r");
            } else if (c == '\\') {
                sb.append("\\\\");
            } else if (c == '"') {
                sb.append("\\\"");
            } else if (c < 32 || c > 0x7f) {
                sb.append("\\u");
                sb.append(hex4(c));
            } else {
                sb.append(c);
            }
        }
        return sb.toString();
    }

    /**
     * Converts the given character to a four-digit hexadecimal string
     * @param c the character to convert
     * @return the string
     */
    private static String hex4(char c) {
        char[] r = new char[] { '0', '0', '0', '0' };
        int i = 3;
        while (c > 0) {
            r[i] = HEX_DIGITS[c & 0xF];
            c >>>= 4;
            --i;
        }
        return new String(r);
    }
}

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