Input dialog loop end early

Question

When the user enters nothing in an input dialog box it ends the loop below. I've debugged the code and name is indeed "" when the user enters nothing.

while(name == "" || name == null){
        name = JOptionPane.showInputDialog("Enter your name:");
    }

Also, When the window containing the input dialog is closed or cancelled, the program doesn't exit the loop.

Can anyone provide some insight for me?

score 2 · Accepted Answer · edited May 23 '17 at 10:32

2

Don't compare strings with name == "". Use "".equals(name) or in your case even name.isEmpty() (available since Java 6).

== is used to compare references, not value of objects. More info here.

Change your code to:

while(name == null || name.isEmpty()){
    name = JOptionPane.showInputDialog("Enter you're name:");
}

edited May 23 '17 at 10:32

Community

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answered Feb 08 '13 at 17:49

Pshemo

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score 1 · Answer 2 · answered Feb 08 '13 at 17:50

1

Never use == to compare Strings in Java.

Use the method equals(String).

See the following link

answered Feb 08 '13 at 17:50

Michael

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Festus Tamakloe · Answer 3 · 2013-02-08T17:53:12.017

0

There is a big difference using "==" oder equals. Try also to use equalsIgnoreCase() to be sure

while(name == null || name.equalsIgnoreCase("")){
        name = JOptionPane.showInputDialog("Enter you're name:");
    }

edited Feb 08 '13 at 17:53

answered Feb 08 '13 at 17:51

Festus Tamakloe

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score 0 · Answer 4 · answered Feb 08 '13 at 17:56

0

Stop comparing strings and start using the Apache Commons Lang StringUtils class. It handles nulls nicely and is well tested. You will want to use StringUtils.isBlamk(name) or StringUtils.isEmpty(name)

answered Feb 08 '13 at 17:56

DwB

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score 0 · Answer 5 · answered Apr 04 '20 at 15:43

The window closing not causing the program to exit the loop is because I needed to add a default close operation by calling JFrame's setDefaultCloseOperation with the parameter JFrame.EXIT_ON_CLOSE. This terminates the JFrame and prevents it from running in the background after the window is closed.

Input dialog loop end early

5 Answers5