Why doesn't While loop start?

Question

I have the following code, everything seems to be working except for the while loop, here is the code:

JLabel img = new JLabel(loadingScreens.getImageIcon(0));
    loadingFrame.setUndecorated(true);
    Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
    double width = screenSize.getWidth();
    double height = screenSize.getHeight();
    int wid = (int) width;
    int hgt = (int) height;
    wid = wid/2;
    hgt = hgt/2;
    wid -=350;
    hgt -=350;
    loadingFrame.setLocation(wid, hgt);

    loadingFrame.setSize(700, 700);
    loadingFrame.setBackground(new Color(0,0,0,0));
    loadingFrame.add(img);
    loadingFrame.setIconImage(loadingScreens.getImage(0));
    loadingFrame.setVisible(true);
    System.out.println("Done 1");
    try{
    Thread.sleep(500);
    System.out.println("Done 2");
    }catch(Exception e){
        System.out.println("exception caught");
    }

    Integer lo = 0;
    System.out.println("Done 3");
    while(lo.equals(256)){

        System.out.println("Started 4");

        loadingFrame.setBackground(new Color(lo, lo, lo, lo));

        loadingFrame.repaint();
        try{
            Thread.sleep(10);
        }catch(Exception e2){

        }
        lo++;
    }

loadingFrame being a basic JFrame.

Any help is useful

Well, it's pretty obvious. Your lo contains the value 0, and it's not equal to 256. — Rohit Jain
– Rohit Jain, Commented Jun 18, 2013 at 18:40
@user2317720, you are setting that value inside the loop -- that very loop you've pointed out never starts. — Kirk Woll
– Kirk Woll, Commented Jun 18, 2013 at 18:42

rgettman · Accepted Answer · 2013-06-18 18:40:20Z

5

A while loop loops while the specified condition is true. You've initialized lo to 0, which is not equal to 256, so the loop body is never entered.

Because you increment lo in the loop, perhaps you meant the opposite:

while(!lo.equals(256)){

The ! operator in Java negates the boolean condition, so that it reads: "while lo is not equal to 256".

answered Jun 18, 2013 at 18:40

rgettman

179k30 gold badges282 silver badges365 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Azad · Accepted Answer · 2013-06-18 18:42:06Z

1

This because while always start with a truth statement not a false and your lo.equals("256") is giving false because lo = 0 and zero never ever equals 256.
If you want to start the loop you have to negation the condition like this :

while(!lo.equals("256") 
//then start the loop

answered Jun 18, 2013 at 18:42

Azad

5,05523 silver badges38 bronze badges

Collectives™ on Stack Overflow

Why doesn't While loop start?

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related