Android dialog show another dialog with a thread.sleep

Question

I have an activity that launch a dialog. This dialog containts a button that show a total diferent dialog wiht a thread.sleep(4000). But the second dialog isn't show. My code:

public boolean onCreateOptionsMenu(Menu menu) {


    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.screen_center, menu);
    Button btnAssign = (Button)findViewById(R.id.btnAssigDataCent);
    btnAssign.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            final Dialog dialog = new Dialog(ScreenCentCon.this);

            dialog.setContentView(R.layout.dialogassign1);
            dialog.setTitle("Choose option");
            Button btnAssign = (Button) dialog.findViewById(R.id.btnDialogCenterAssign);
            btnAssign.setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                    dialog.dismiss();

                    final Dialog dialog2 = new Dialog(ScreenCentCon.this);
                    dialog2.setContentView(R.layout.dialogassign2);
                    dialog2.setTitle("Wait");

                    dialog2.show();
                    try {
                        synchronized (this) {
                            Thread.sleep(4000);
                            dialog2.dismiss();
                        }

                    } catch (InterruptedException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }                   
                }
            });
            dialog.show();
        }
    });

}

The code only show the first dialog, but wait 4s to dismis the activity.

Answer 1

Thread.sleep() will completely block the UI thread, and thus prevent the dialog from even being drawn. In general it's a very bad idea.

If you want to show a dialog for 4 seconds and then dismiss it automatically, you should use Handler.postDelayed(). Something like:

mHandler = new Handler();

...

dialog2.show();
mHandler.postDelayed(new Runnable()
{
    @Override
    public void run() {
        dialog2.dismiss();
    } 
}, 4000);