public static void unescapeJava(Writer out, String str) throws IOException {
        if (out == null) {
            throw new IllegalArgumentException("The Writer must not be null");
        }
        if (str == null) {
            return;
        }
        int sz = str.length();
        StringBuilder unicode = new StringBuilder(4);
        boolean hadSlash = false;
        boolean inUnicode = false;
        for (int i = 0; i < sz; i++) {
            char ch = str.charAt(i);
            if (inUnicode) {
                // if in unicode, then we're reading unicode
                // values in somehow
                unicode.append(ch);
                if (unicode.length() == 4) {
                    // unicode now contains the four hex digits
                    // which represents our unicode character
                    try {
                        int value = Integer.parseInt(unicode.toString(), 16);
                        out.write((char) value);
                        unicode.setLength(0);
                        inUnicode = false;
                        hadSlash = false;
                    } catch (NumberFormatException nfe) {
                        throw new RuntimeException("Unable to parse unicode value: " + unicode, nfe);
                    }
                }
                continue;
            }
            if (hadSlash) {
                // handle an escaped value
                hadSlash = false;
                switch (ch) {
                    case '\\':
                        out.write('\\');
                        break;
                    case '\'':
                        out.write('\'');
                        break;
                    case '\"':
                        out.write('"');
                        break;
                    case 'r':
                        out.write('\r');
                        break;
                    case 'f':
                        out.write('\f');
                        break;
                    case 't':
                        out.write('\t');
                        break;
                    case 'n':
                        out.write('\n');
                        break;
                    case 'b':
                        out.write('\b');
                        break;
                    case 'u':
                        {
                            // uh-oh, we're in unicode country....
                            inUnicode = true;
                            break;
                        }
                    default :
                        out.write(ch);
                        break;
                }
                continue;
            } else if (ch == '\\') {
                hadSlash = true;
                continue;
            }
            out.write(ch);
        }
        if (hadSlash) {
            // then we're in the weird case of a \ at the end of the
            // string, let's output it anyway.
            out.write('\\');
        }
    }
public static void unescapeJava ( Writer out , String str ) throws IOException { if ( out == null ) { throw new IllegalArgumentException ( "The Writer must not be null" ) ; } if ( str == null ) { return ; } int sz = str . length ( ) ; StringBuilder unicode = new StringBuilder ( 4 ) ; boolean hadSlash = false ; boolean inUnicode = false ; for ( int i = 0 ; i < sz ; i ++ ) { char ch = str . charAt ( i ) ; if ( inUnicode ) { unicode . append ( ch ) ; if ( unicode . length ( ) == 4 ) { try { int value = Integer . parseInt ( unicode . toString ( ) , 16 ) ; out . write ( ( char ) value ) ; unicode . setLength ( 0 ) ; inUnicode = false ; hadSlash = false ; } catch ( NumberFormatException nfe ) { throw new RuntimeException ( "Unable to parse unicode value: " + unicode , nfe ) ; } } continue ; } if ( hadSlash ) { hadSlash = false ; switch ( ch ) { case '\\' : out . write ( '\\' ) ; break ; case '\'' : out . write ( '\'' ) ; break ; case '\"' : out . write ( '"' ) ; break ; case 'r' : out . write ( '\r' ) ; break ; case 'f' : out . write ( '\f' ) ; break ; case 't' : out . write ( '\t' ) ; break ; case 'n' : out . write ( '\n' ) ; break ; case 'b' : out . write ( '\b' ) ; break ; case 'u' : { inUnicode = true ; break ; } default : out . write ( ch ) ; break ; } continue ; } else if ( ch == '\\' ) { hadSlash = true ; continue ; } out . write ( ch ) ; } if ( hadSlash ) { out . write ( '\\' ) ; } }
<p>Unescapes any Java literals found in the <code>String</code> to a
<code>Writer</code>.
<p>
For example, it will turn a sequence of <code>'\'</code> and
<code>'n'</code> into a newline character, unless the <code>'\'</code>
is preceded by another <code>'\'</code>.
<p>
A <code>null</code> string input has no effect.

@param out  the <code>Writer</code> used to output unescaped characters
@param str  the <code>String</code> to unescape, may be null
@throws IllegalArgumentException if the Writer is <code>null</code>
@throws IOException if error occurs on underlying Writer