Question

Possible Duplicate:
Equal strings aren't equal (==) in Java?

From Eclipse’s Display window:

 messages.get(i).getMsg() == lastMsg
 (boolean) false
 messages.get(i).getMsg().length()
 (int) 14
 lastMsg.length()
 (int) 14
 messages.get(i).getMsg()
 (java.lang.String) INSERT QUARTER
 lastMsg
 (java.lang.String) INSERT QUARTER

Fairly new to Java. How can the first statement be false? Am I missing something ridiculously simple here?

Answer 1

When you compare strings in Java, you should do that by calling the equals() method, not by using the == operator.

The == operator does not test if the value or content of two objects is the same. It simply checks if the two expressions on both sides of the == refer to the exact same object. If you have two String objects that have the same content, but that are distinct objects, then == will return false.

(There is a minor complication to this though: the compiler does some clever tricks so that if you use string literals, == will actually return true).

String msg = messages.get(i).getMsg();
System.out.println(msg == lastMsg); // false
System.out.println(msg.equals(lastMsg)); // true