Is it safe to use ==/!= while comparing Character?

Character being a boxed type is it safe to use ==/!= while comparing Character types?

  public static void main(String[] args) {

        Character c1 = 'd';
        Character c2 = (char) getInt();

        System.out.println(c1 == c2);
    }

    public static int getInt() {

        return 100;
    }

The following works as expected (true). However, are there cases where comparing Character with same value using == would lead to false? (Hence, do we have to use '.equals()' while comparing boxed primitive types?

CodePudding user response：

No, it's not safe. You must use equals().

Demonstration:

System.out.println(Character.valueOf('Ü') == Character.valueOf('Ü'));
// -> false

Note that if you use autoboxing or Character.valueOf(), then some characters (ASCII characters) are cached and the same Character instance is reused, so == may return true for the same value:

System.out.println(Character.valueOf('A') == Character.valueOf('A'));
// -> true (on my machine)

But it doesn't work for all characters, and it won't work if you call the deprecated new Character(...) explicitly.

CodePudding user response：

tl;dr

Use code points, not char/Character.

"d".codePointAt( 0 ) == 100  // true.

Details

The Answer by Alex Shesterov is correct. But bigger picture, you should not be using Character objects.

Character is broken

The Character class is a wrapper class for the primitive type char. The char/Character type is legacy as of Java 2, and is essentially broken. As a 16-bit value, it is physically incapable of representing most characters.

For example, try running:

 System.out.println( Character.valueOf( '