How to Unescape Java String Literals?

How to Unescape a Java String Literal in Java?

Java doesn't provide a straightforward function for unescaping string literals. This task requires manually converting character escape sequences into their corresponding characters.

Common Character Escapes

Escape Sequence	Character
	Backslash
n	Newline
r	Carriage return
t	Tab
b	Backspace
f	Form feed
"	Double quote
'	Single quote

Unescaping String Literals

One approach to unescape string literals is to use a custom function that iterates through the string, identifying escape sequences, and replacing them with the appropriate characters.

public static String unescape(String str) {
    StringBuilder sb = new StringBuilder();
    for (int i = 0; i < str.length(); i++) {
        char c = str.charAt(i);
        if (c == '\') {
            i++;
            switch (str.charAt(i)) {
                case 'n':
                    sb.append('\n');
                    break;
                case 'r':
                    sb.append('\r');
                    break;
                case 't':
                    sb.append('\t');
                    break;
                case 'b':
                    sb.append('\b');
                    break;
                case 'f':
                    sb.append('\f');
                    break;
                case '\"':
                    sb.append('\"');
                    break;
                case '\'':
                    sb.append('\'');
                    break;
                case '\':
                    sb.append('\');
                    break;
                default:
                    sb.append(c); // Unrecognized escape sequence
            }
        } else {
            sb.append(c);
        }
    }
    return sb.toString();
}

Example:

String original = "\\"Hello, World!\\"";
String unescaped = unescape(original);
System.out.println(unescaped); // Output: "Hello, World!"

Libraries for String Unescaping

Some third-party libraries also provide functions for unescaping string literals. For example, the Apache Commons Lang library has the following method:

public static String unescapeJava(String str)

This method can be used to unescape Java string literals, including escape sequences not covered by the basic approach mentioned above.

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