Blinking Screen Activity Android

Question

I'm trying to test something out, but all I need is an activity that blinks between black and white screens at an interval of 1 second. I've looked at postDelayed, but I'm still not sure how I would implement that. This is what I have right now, but it doesn't "blink"

MainActivity:

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;

public class Blink extends Activity {
    int i = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_blink);

        while (i == 0) {
            Handler handler = new Handler();
            handler.postDelayed(new Runnable() {
                public void run() {
                    changeColor();
                }
            }, 1000);
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void changeColor() {
        if (findViewById(R.id.mylayout).getBackground().equals("#ffffff")) {
            findViewById(R.id.mylayout).setBackgroundResource(Color.BLACK);
        } else {
            findViewById(R.id.mylayout).setBackgroundResource(Color.WHITE);

        }
    }
}

Updated Code:

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;

public class Blink extends Activity {
    int i = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_blink);

        Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            public void run() {
                changeColor();
            }
        }, 1000);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void changeColor() {
        if (i == 0) {
            findViewById(R.id.mylayout).setBackgroundColor(Color.WHITE);
            i++;
        } else if (i == 1) {
            findViewById(R.id.mylayout).setBackgroundColor(Color.BLACK);
            i--;

        }
    }
}

Update 2:

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;

public class Blink extends Activity {
    int i = 0;
    Boolean bool = false;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_blink);

        Handler handler = new Handler();
        handler.postDelayed(new Runnable() {
            public void run() {
                changeColor();
            }
        }, 1000);

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void changeColor() {
        if (bool) {
            findViewById(R.id.mylayout).setBackgroundColor(Color.WHITE);
            bool = false;
        } else {
            findViewById(R.id.mylayout).setBackgroundColor(Color.BLACK);
            bool = true;

        }
    }
}

no need to use while loop when u are using `handler.postDelayed` just try it without while loop — ρяσѕρєя K, Mar 13 '13 at 17:55
What if I want the activity to keep blinking black and white? — EGHDK, Mar 13 '13 at 17:57
handler.postDelayed always run after 1 sec just use some flag to change bg color of layout — ρяσѕρєя K, Mar 13 '13 at 17:58
Okay, I updated my code. Now my screen goes from black to white, but doesn't go black again. — EGHDK, Mar 13 '13 at 18:02
@EGHDK : plz edit you latest code with question and use one flag like : `boolean bool=flase ; if(bool){change bg here and make bool flase}else{change bg here and make bool true}` and also increase delay time to 3-4 sec — ρяσѕρєя K, Mar 13 '13 at 18:07
Hmmm... I just updated my code, and now the screen just stays black. — EGHDK, Mar 13 '13 at 18:20

score 0 · Answer 1 · edited May 23 '17 at 11:57

0

I narrowed down the exact question I should be asking right here: Why doesn't this postDelayed run forever?

To fix this code, all I had to do was add handler.postDelayed(this, 1000); inside of run.

edited May 23 '17 at 11:57

Community

1
1

answered Mar 13 '13 at 22:29

EGHDK

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Blinking Screen Activity Android

Updated Code:

Update 2:

1 Answers1