How i can change few images endlessly? - Java

Issue

I want for example 3 images to change every 2 or 3 seconds endlessly repeating the circle.

// Like this:

ImageView background = (ImageView)findViewById(R.id.main_background2);
background.setBackgroundResource(R.drawable.main_background1);
background.setBackgroundResource(R.drawable.main_background2);
background.setBackgroundResource(R.drawable.main_background3);

// And do something further

How can i do this. Show code pls.

Thank you in advance

Solution

You can set a Thread to run on a continuous loop when the Activity is created (onCreate). The Thread can include a delay, and can update the UI with the next image. However, note that "you cannot update the UI from any thread other than the UI thread or the 'main' thread." (https://developer.android.com/guide/components/processes-and-threads). Try this:

    import androidx.appcompat.app.AppCompatActivity;
    import android.os.Bundle;
    import android.widget.ImageView;

    public class MainActivity extends AppCompatActivity {

    ImageView background;
    public int imgCount;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        background = (ImageView)findViewById(R.id.imageView);
        imgCount = 1;
        runThread();
    }

    private void runThread() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                // set thread to run on a continuous loop
                while (true) {
                    try {
                        Thread.sleep(5000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    imgCount++;
                    if (imgCount > 3) imgCount = 1;

                    // UI must be updated on the UI thread
                    background.post(new Runnable() {
                        public void run() {

                            switch (imgCount) {
                                case 1:
                                    background.setImageResource(R.drawable.main_background1);
                                    break;
                                case 2:
                                    background.setImageResource(R.drawable.main_background2);
                                    break;
                                case 3:
                                    background.setImageResource(R.drawable.main_background3);
                                    break;
                            }
                        }
                    });
                }
            }
        }).start();
    }
}

Answered By - Jonathan Furminger