I wanted to delay a for loop without using Thread.sleep
because that method make my whole application hang. I tried to use handler
but it doesn't seems to work inside a loop. Can someone please point out the mistake in my code.
public void onClick(View v) {
if (v == start)
{
for (int a = 0; a<4 ;a++) {
Handler handler1 = new Handler();
handler1.postDelayed(new Runnable() {
ImageButton[] all= {btn1, btn2, btn3, btn4};
btn5 = all[random.nextInt(all.length)];
btn5.setBackgroundColor(Color.RED);
@Override
public void run() {
}
}, 1000);
}
}
}
Basically what I wanted to do is that I got 4 ImageButton
and I change each of their background to red by using a loop in order. Thats why I need a delay inside my loop, if not all the ImageButton
will just directly turn red without showing which ImageButton
turn first.
Your for loop should be:
final ImageButton[] all= {btn1, btn2, btn3, btn4};
Handler handler1 = new Handler();
for (int a = 1; a<=all.length ;a++) {
handler1.postDelayed(new Runnable() {
@Override
public void run() {
ImageButton btn5 = all[random.nextInt(all.length)];
btn5.setBackgroundColor(Color.RED);
}
}, 1000 * a);
}
}
This way it achieves your desired behavior of staggering the color change.
Edited for syntax
You can use a Handler
instead of for loop. You should not call Thread.sleep()
on the UI thread.
final Handler handler = new Handler();
Runnable runnable = new Runnable() {
@Override
public void run() {
// do something
handler.postDelayed(this, 1000L); // 1 second delay
}
};
handler.post(runnable);
The following code doing the task in every second:
final Handler handler = new Handler();
Runnable task = new Runnable() {
@Override
public void run() {
Log.d(TAG, "Doing task");
handler.postDelayed(this, 1000);
}
};
handler.post(task);
Try this :
public void onClick(View v) {
if (v == start) {
for (int a = 0; a<4 ;a++) {
Handler handler1 = new Handler();
handler1.postDelayed(new Runnable() {
ImageButton[] all= {btn1, btn2, btn3, btn4};
@Override
public void run() {
btn5 = all[random.nextInt(all.length)];
btn5.setBackgroundColor(Color.RED);
}
}, 1000);
}
}
}
Example for Delay :
final Handler handler = new Handler();
handler.postDelayed(new Runnable() {
@Override
public void run() {
// Do something after 5s = 5000ms
buttons[inew][jnew].setBackgroundColor(Color.Red);
}
}, 5000);
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