Question

I want to create a subclass of linear layout,and it’s background color must be change Black or White.I wrote this code:

public class MyLayout extends LinearLayout implements Runnable {

    int color = 0xFFFFFFFF;

    public MyLayout(Context context) {
        super(context);
        Thread t = new Thread(this);
        t.start();
    }

    @Override
    public void run() {
        while (true) {
            try {
                Thread.sleep(1000);
                if(color == 0xFF000000){
                    color = 0xFFFFFFFF;
                }else{
                    color = 0xFF000000;
                }
                this.setBackgroundColor(color);
                postInvalidate();
                System.out.println("Color >> " + color);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

}

And then I set it as ContentView of my Activity:

@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new MyLayout(this));
    }

After running App in Emulator,run method of MyLayout executes without any exception,but backgroung color is always Black.What I’m doing wrong?

Answer 1

In following up @Hisham Muneer,I send instance of my Activity to my class and it works.runOnUiThread is a method in Activity class.This is finall code:

public class MyLayout extends LinearLayout implements Runnable {

    int color = 0xFFFFFFFF;
    Activity context;

    public MyLayout(Activity context) {
        super(context);
        this.context = context;
        myView = this;
        Thread t = new Thread(this);
        t.start();
    }

    private View myView;

    @Override
    public void run() {

        try {
            while (true) {
                Thread.sleep(1000);

                context.runOnUiThread(new Runnable() {

                    @Override
                    public void run() {
                        // TODO Auto-generated method stub
                        if (color == 0xFF000000) {
                            color = 0xFFFFFFFF;
                        } else {
                            color = 0xFF000000;
                        }
                        myView.setBackgroundColor(color);
                        postInvalidate();
                        System.out.println("Color >> " + color);
                    }
                });
            }
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}