Change layout background dynamically and automatically

Question

I have a Layout something like this.

xml

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:id="@+id/mylayout" > </RelativeLayout>

java - Then you can dynamically change the background of the layout using below code

public class MainActivity extends Activity {

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

        RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.mylayout);
        int images[] = {R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4};

        relativeLayout.setBackgroundResource(images[getRandomNumber()]);
         private Timer myTimer;
         myTimer = new Timer();
         myTimer.schedule(new TimerTask() 
         {          
            @Override
            public void run() 
            {
                TimerMethod();
            }
         }, 0, 9000);
    }

private void TimerMethod()
           {
               new Handler().postDelayed(new Runnable() {

                @Override
                public void run() {

                    //TODO after 9 sec
                     relativeLayout.setBackgroundResource(images[getRandomNumber()]);
                }
            }, 9000);
        }
}

Here is the Log Trace

01-04 01:08:15.307: E/AndroidRuntime(30200): FATAL EXCEPTION: Timer-0
01-04 01:08:15.307: E/AndroidRuntime(30200): java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
01-04 01:08:15.307: E/AndroidRuntime(30200):    at android.os.Handler.<init>(Handler.java:121)
01-04 01:08:15.307: E/AndroidRuntime(30200):    at info.androidhive.slidingmenu.LoginActivity.TimerMethod(LoginActivity.java:55)
01-04 01:08:15.307: E/AndroidRuntime(30200):    at info.androidhive.slidingmenu.LoginActivity.access$0(LoginActivity.java:53)
01-04 01:08:15.307: E/AndroidRuntime(30200):    at info.androidhive.slidingmenu.LoginActivity$1.run(LoginActivity.java:48)
01-04 01:08:15.307: E/AndroidRuntime(30200):    at java.util.Timer$TimerImpl.run(Timer.java:284)

what i want to try is to change it automatically while on the activity.

hey you want to perform this continuously after some interval or only when user comes back to the activity ? — AndyN, Dec 27 '13 at 05:33
example situation.. Im in my app homepage, and while im on it my background is continuously changing after some interval. — AndroidNewbie, Dec 27 '13 at 05:36
then for such situation you should make use of timer to achieve this. — AndyN, Dec 27 '13 at 05:39
yes refer to zanky's answer. It'll solve your problem. add that snippet to your onCreate() method. — AndyN, Dec 27 '13 at 05:44
You can refer http://stackoverflow.com/questions/3875184/cant-create-handler-inside-thread-that-has-not-called-looper-prepare link to solve your problem. — Zankhna, Jan 13 '14 at 06:19

Swayam · Answer 1 · 2013-12-27T10:33:16.117

3

onCreate() is called only once, when the Activity is first opened. After you navigate away, onPause() is called and later when you return to the Activity, onResume() is called.

So, to change the background every time you navigate to the Activity, shift your code to change the background from onCreate() to onResume().

public class MainActivity extends Activity {
RelativeLayout relativeLayout;
int images[];
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    relativeLayout = (RelativeLayout) findViewById(R.id.mylayout);
    images[]  = {R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4};     
}

protected void onResume()
{
    if(relativeLayout != null)
      relativeLayout.setBackgroundResource(images[getRandomNumber()]);

}

private int getRandomNumber() {
    //Note that general syntax is Random().nextInt(n)
    //It results in range 0-4
    //So it should be equal to number of images in images[] array
    return new Random().nextInt(4);
}}

edited Dec 27 '13 at 10:33

answered Dec 27 '13 at 05:00

Swayam

16,294
14
64
102

Updated my answer. That should do it. – Swayam Dec 27 '13 at 05:27
1

there is an error on **images** `relativeLayout.setBackgroundResource(images[getRandomNumber()]);` – AndroidNewbie Dec 27 '13 at 05:33
Yeah, okay. In my haste, I forgot to declare images[] globally. I thought you might figure that out. Anyway, fixed the declaration. Check the answer now. – Swayam Dec 27 '13 at 10:26
Actually, onCreate will also be called when the Activity is killed by Android system (e.g. when orientation or language changes) – Daniels Šatcs Jul 07 '16 at 19:19

Zankhna · Answer 2 · 2013-12-30T05:10:16.120

2

You can do this by making use of Timers and Handlers Try this code:

   public class MainActivity extends Activity {

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

        RelativeLayout relativeLayout = (RelativeLayout) findViewById(R.id.mylayout);
        int images[] = {R.drawable.image1, R.drawable.image2, R.drawable.image3, R.drawable.image4};

        relativeLayout.setBackgroundResource(images[getRandomNumber()]);
         private Timer myTimer;
         myTimer = new Timer();
         myTimer.schedule(new TimerTask() 
         {          
            @Override
            public void run() 
            {
                TimerMethod();
            }
         }, 0, 9000);
    }

private void TimerMethod()
           {
               new Handler().postDelayed(new Runnable() {

                @Override
                public void run() {

                    //TODO after 9 sec
                     relativeLayout.setBackgroundResource(images[getRandomNumber()]);
                }
            }, 9000);
        }
}

edited Dec 30 '13 at 05:10

answered Dec 27 '13 at 05:13

Zankhna

4,570
9
62
103

1

thanks to this but where should i call its function? – AndroidNewbie Dec 27 '13 at 05:22
1

pardon :) `TimerMethod()` must be called in onCreate()? snips please? thank you. – AndroidNewbie Dec 27 '13 at 05:35
1

there is something wrong with the code sir it says cannot call handler because your not using looper "something".. – AndroidNewbie Dec 29 '13 at 05:43
1

i havent try this for now. i will later and i will post here thank you. – AndroidNewbie Jan 02 '14 at 20:59
1

It doesnt work @zanky see my Log Trace above i updated my post – AndroidNewbie Jan 03 '14 at 17:11

AndyN · Answer 3 · 2013-12-27T05:31:18.370

0

Try calling your relativeLayout.setBackgroundResource(images[getRandomNumber()]); on your activity's onResume() method like this.

protected void onResume()
{
    if(relativeLayout != null){
          relativeLayout.setBackgroundResource(images[getRandomNumber()]);
    }
}

Hope this helps.

edited Dec 27 '13 at 05:31

answered Dec 27 '13 at 05:07

AndyN

1,742
1
15
30

score 0 · Answer 4 · answered Dec 27 '13 at 05:12

0

In onCreate Method your code will execute only once and if you want it to change after some time interval then use TimerTask or you can use Handler also.

answered Dec 27 '13 at 05:12

Jitesh Dalsaniya

1,917
3
20
36

score 0 · Answer 5 · answered Jun 22 '17 at 19:41

first create transition_drawable.xml in drawable res

<transition xmlns:android="http://schemas.android.com/apk/res/android">
 <item android:drawable="@drawable/one"/>
 <item android:drawable="@drawable/two"/>
 <item android:drawable="@drawable/three"/>

`

and in your layout`

android:background="@drawable/transition_drawable"

and in your activity.java

int DrawableImage[] = {R.drawable.one , R.drawable.two, R.drawable.three};
final Handler handler = new Handler();
    final int[] i = {0};
    final int[] j = {1};
    handler.postDelayed(new Runnable() {
        @Override
        public void run() {
            runOnUiThread(new Runnable() {
                @Override
                public void run() {
                    Resources res = getApplicationContext().getResources();
                    TransitionDrawable out = new TransitionDrawable(new Drawable[]{res.getDrawable(DrawableImage[i[0]]), res.getDrawable(DrawableImage[j[0]])});
                    out.setCrossFadeEnabled(true);
                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
                        yourlayout.setBackground(out);
                    }
                    out.startTransition(2000);
                    i[0]++;
                    j[0]++;
                    if (j[0] == DrawableImage.length) {
                        j[0] = 0;
                    }
                    if (i[0] == DrawableImage.length) {
                        i[0] = 0;
                    }
                    handler.postDelayed(this, 4000);
                }
            });
        }
    }, 0);

score 0 · Answer 6 · answered Feb 17 '19 at 15:33

I made it work Like this:

private int[] backgroundImages = {R.drawable.bg1, R.drawable.bg2, R.drawable.bg3, R.drawable.bg4};
RelativeLayout background = findViewById(R.id.background);
background.setBackgroundResource(backgroundImages[new Random().nextInt(4)]);
Timer timer = new Timer();
    timer.schedule(new TimerTask() {
        @Override
        public void run() {
            new Handler(Looper.getMainLooper()).postDelayed(new Runnable() {
                @Override
                public void run() {
                    background.setBackgroundResource(backgroundImages[new Random().nextInt(4)]);
                }
            }, 3000);
        }
    }, 0, 3000);

score -1 · Answer 7 · edited Feb 04 '19 at 00:26

I know this old question but I will post my answer for others you can use the following code

public class myActivity extends AppCompatActivity {

    RelativeLayout relativeLayout;
    int images[];

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

        relativeLayout = (RelativeLayout) findViewById(R.id.mylayout);
        images  = new int[{R.drawable.fighter3,R.drawable.sky,R.drawable.yellow_bullet,R.drawable.chicken3};

        //Create the timer object which will run the desired operation on a schedule or at a given time
        Timer timer = new Timer();

        //Create a task which the timer will execute.  This should be an implementation of the TimerTask interface.
        //I have created an inner class below which fits the bill.
        MyTimer mt = new MyTimer();

        //We schedule the timer task to run after 1000 ms and continue to run every 1000 ms.
        timer.schedule(mt, 1000, 1000);

    }

    private int getRandomNumber() {
        //Note that general syntax is Random().nextInt(n)
        //It results in range 0-4
        //So it should be equal to number of images in images[] array
        return new Random().nextInt(4);
    }

    class MyTimer extends TimerTask {

        public void run() {

            //This runs in a background thread.
            //We cannot call the UI from this thread, so we must call the main UI thread and pass a runnable
            runOnUiThread(new Runnable() {

                public void run() {
                    Random rand = new Random();
                    //The random generator creates values between [0,256) for use as RGB values used below to create a random color
                    //We call the RelativeLayout object and we change the color.  The first parameter in argb() is the alpha.
                    relativeLayout.setBackgroundResource(images[getRandomNumber()]);
                }
            });
        }
    }
}

Change layout background dynamically and automatically

7 Answers7