CODEWITHSUNDEEP
javaarraysswinguser-interfacecolors
crazychris119
crazychris119

Reputation: 51

Looping through colours in a window

I'm a beginner in Java programming and have come across an issue (probably an easy one to solve).

I am experimenting with Java GUI and wish to create a window in which the colours of an array are cycled through until there are no more colours. I believe I can do this using a for loop and cycling through the array, however I do not know how to loop through the background colour.

Any help and explanation would be appreciated.

public void flashColor()  { 

    Color [] color = { Color.red,Color.orange,Color.green };

    int i = 0;
    for(i=0;i<color.length;i--){

        getContentPane().setBackground(Color(i));
    }
}

Upvotes: 1

Views: 913

Answers (1)

Hovercraft Full Of Eels
Hovercraft Full Of Eels

Reputation: 285405

This line tells me:

getContentPane().setBackground(Color(i));

that yours appears to be a Swing GUI (a key bit of information that you left out of your question!), and so you need to take Swing threading into consideration. Your current code will in fact loop through all the colors, but it will do so immediately, and on the Swing thread so that the GUI will have no way to paint any of the colors other than the last one. The solution: use a Swing Timer and not a for loop. Inside the timer advance an index int variable and use it to show the color.

Something like:

getContentPane().setBackground(colorArray[0]);
int delay = 1000; // for 1 second
Timer myTimer = new Timer(delay, new ActionListener() {

    int index = 0;
    public void actionPerformed(ActionEvent e) {
       index++;
       if (index >= colorArray.length) {
          ((Timer)e.getSource()).stop(); // stop the timer
       } else {
          getContentPane().setBackground(colorArray[index]);
       }
    }

});
myTimer.start();

The code has not been tested, and you'll want to read the Swing Timer tutorial for the details.

Note the key here is that yes you need to loop, and to pause (so that the color can be seen) but you need to do your looping and pausing in a thread thread is off of the Swing event dispatch thread (or EDT). Yes you could do this using a SwingWorker, but that is a way more difficult way to do this. It is far easier to use a Swing Timer to do this for you. Note that it uses a background thread invisibly for you.

Upvotes: 2

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