[SOLVED] The == operator in Java

The == operator in Java

the following is true in Java

"abc"=="abc"

Why? The two Strings are two different objects, they should not have the same object identity?

Solution

Java keeps all literals (strings placed in code) in special part of JVM memory. If there are two or more identical literals JVM just pointer to the same object instead of creating few strings with the same content.

So:

"ab" == "ab" // true - because they are the same objects

but:

"ab" == new String("ab") // false - because new String(...) is new String not literal

You can get or move your String to the special memory by invoking intern() method.

    String ab1 = "ab";
    String ab2 = new String("ab");
    // ab1 == ab2 is false as described above
    ab2 = ab2.intern();
    // ab1 == ab2 but now it's true because ab2 pointers to "ab" in special part of memory.