Java String Unescape unescape(String input)

Description

unescape

License

BSD License

Declaration

public static String unescape(String input) 

Method Source Code

//package com.java2s;
// BSD License (http://lemurproject.org/galago-license)

public class Main {
    public static String unescape(String input) {
        StringBuilder builder = new StringBuilder();

        int i = 0;
        while (i < input.length()) {
            char delimiter = input.charAt(i);
            i++; // consume letter or backslash

            if (delimiter == '\\' && i < input.length()) {

                // consume first after backslash
                char ch = input.charAt(i);
                i++;/*from  w ww .j  av  a 2  s  .  c  om*/

                if (ch == '\\' || ch == '/' || ch == '"' || ch == '\'') {
                    builder.append(ch);
                } else if (ch == 'n')
                    builder.append('\n');
                else if (ch == 'r')
                    builder.append('\r');
                else if (ch == 't')
                    builder.append('\t');
                else if (ch == 'b')
                    builder.append('\b');
                else if (ch == 'f')
                    builder.append('\f');
                else if (ch == 'u') {

                    StringBuilder hex = new StringBuilder();

                    // expect 4 digits
                    if (i + 4 > input.length()) {
                        throw new RuntimeException("Not enough unicode digits! ");
                    }
                    for (char x : input.substring(i, i + 4).toCharArray()) {
                        if (!Character.isLetterOrDigit(x)) {
                            throw new RuntimeException("Bad character in unicode escape.");
                        }
                        hex.append(Character.toLowerCase(x));
                    }
                    i += 4; // consume those four digits.

                    int code = Integer.parseInt(hex.toString(), 16);
                    builder.append((char) code);
                } else {
                    throw new RuntimeException("Illegal escape sequence: \\" + ch);
                }
            } else { // it's not a backslash, or it's the last character.
                builder.append(delimiter);
            }
        }

        return builder.toString();
    }
}

Related

1. unescape(String escaped)
2. unescape(String escaped)
3. unescape(String escaped, char escape)
4. unescape(String escapedMessage)
5. unescape(String input)
6. unescape(String input, char escapeChar)
7. unescape(String line)
8. unescape(String line)
9. unescape(String line, int start, int end)