Representing ^A (Unicode \u0001) correctly in Java when passed as argument

Question

 public class TestU {
    public static void main(String[] args) {
        String str = "\u0001";
        System.out.println("str-->"+str);
        System.out.println("arg[0]-->"+args[0]);
    }
}

Output :

str-->^A
arg[0]-->\u0001

I am passing arg[0] as \u0001

I executed this code in linux, the command line variable is not taken as unicode special character.

Solution

The argument you pass from command line is not actually unicode character but it's a String of unicode character which is escaped with \. Ultimately, your String will become \\u0001 and that's why it is printing \u0001. Same way, if you enter \ as a command line argument it will become \\ to escape your backward slash.

While the String you have declared in main is actually unicode character.

String escapedstring = "\\u0001";//in args[0]
String unicodeChar = "\u0001";// in str

So, now you want \\u0001 to be converted into \u0001 and there are lot of ways to achieve that. i.e. you can use StringEscapeUtils#unescapeJava method of utility or you can also try following way.

String str = "\\u0001";
char unicodeChar = (char) Integer.parseInt(str.substring(2));
System.out.println(unicodeChar);

NOTE : You can find other ways to convert unicode String to unicode characters in following question.(Already provided in comment by Marcinek)

• How to convert a string with Unicode encoding to a string of letters