CODEWITHSUNDEEP
javastringequalsjlabeljtextfield
anon
anon

Reputation:

JLabel and JTextField string comparison

When I use JLabel string comparison with == works fine

private JLabel someJLabel = new JLabel("some text");
...
System.out.println (someJLabel.getText() == "some text"); // returns true

but when I use JTextField

private JTextField someJTextField = new JTextField("some text");
...
System.out.println (someJTextField.getText() == "some text"); // returns false

I know that if I used someJTextField.getText().equals("some text"); it would work fine.

So why it works with JLabel but not JTextField

EDIT: yes I know that I should use .equals with string, I have read this article http://javatechniques.com/blog/string-equality-and-interning/ but it's known already that I will use "some text" so it could refer to same string object

Upvotes: 2

Views: 3348

Answers (4)

Gandalf the white
Gandalf the white

Reputation: 11

There is a bit difference in == operator and.equals method. == operator compares two objects while .equals method compare values in two object.

In your case you are comparing two different object although both may be holding same values. In your case you may use .equals method .This will definitely help!

Upvotes: 0

Matt
Matt

Reputation: 95

Compare Strings with .equals(Object obj)

== should mostly be used with only primitive objects.

Upvotes: 0

Ashwinee K Jha
Ashwinee K Jha

Reputation: 9317

JTextField internally copies the string to its modifiable document object to support editing so you don't get back the same string in getText().

Upvotes: 1

korifey
korifey

Reputation: 3519

It's not related to JTextField and JLabel.

JVM uses String pool internally and sometimes == operator works because different strings (in your case "some text") points to the same string in pool. Look at question here

Never compare strings with == !!!

Upvotes: 3

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