Android screen orientation change

Question

I'm making a program that when I press a button this change the background color but I have a problem with, when I change the screen orientation this change again the color to the predefined and I dont know how to solve this problem... Here is my code.

public class MainActivity extends Activity implements OnClickListener {

    LinearLayout myLayout;
    LinearLayout myLayout2;

    // Declare UI elements
    private Button firstButton, secondButton, thirdButton, fourthButton, fifthButton;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main); // Our only layout for this app is main.xml

        myLayout = (LinearLayout) findViewById(R.id.myLayout);
        myLayout2 = (LinearLayout) findViewById(R.id.myLayout2);

        // Initialize the UI components

        firstButton = (Button) findViewById(R.id.button1); 
        // When we creating a button and if we expect that to use for event handling we have to set the listener
        firstButton.setOnClickListener(this);
        secondButton = (Button) findViewById(R.id.button2);
        secondButton.setOnClickListener(this);
        thirdButton = (Button) findViewById(R.id.button3);
        thirdButton.setOnClickListener(this);
        fourthButton = (Button) findViewById(R.id.button4);
        fourthButton.setOnClickListener(this);
        fifthButton = (Button) findViewById(R.id.button5);
        fifthButton.setOnClickListener(this);

    }

    }    

Answer 1

The problem is that when the orientation is changed, the activity is restarted. There are multiple ways to fix that.

One way is to make it so that the activity won't restart when the orientation is changed. Here's how to do that:

Add android:configChanges="orientation|screenSize" to your <activity tag, which is in your AndroidManifest.xml, like so:

<activity
    android:name="UserIdActivity"
    android:label="@string/app_name"
    android:configChanges="orientation|screenSize" />

Rastikan's answer did it slightly differently, but his way of doing it won't work for any API after API 12 (source and this too). My way above, you don't actually need to call onConfiguationChanged in your activity class.

Another way of doing it would to use onSaveInstanceState(Bundle savedInstanceState) like Rastikan did.

Another way of doing it would be to let the activity restart itself, but then using the onResume() method to change the background colour, if necessary, when the activity is restarted. Like this:

public boolean changeColor = false;

// set changeColor to be true whenever you change the background colour

public void onResume()
{
    if (changeColor) {
        // change the background color
    }
}

Answer 2

Here is a short/alternate version assuming a view (view1) of some sort.

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Color;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class MainActivity extends Activity {

    private static final int DEFAULT_COLOR = Color.WHITE;

    private int myColor;
    // Assuming a 'view' of some sort
    private View myView;

    // Declare UI elements
    private Button firstButton;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main); // Our only layout for this app
                                                // is main.xml

        myView      = (View)   findViewById( R.id.view1   );
        firstButton = (Button) findViewById( R.id.button1 );

        Log.i("MainActivity", "onCreate"
                + ((null == savedInstanceState) ? "(null)"
                        : "(savedInstanceState)"));

        if (savedInstanceState != null) {
            myColor = savedInstanceState.getInt("COLOR");
        } else {
            myColor = DEFAULT_COLOR;
        }

        myView.setBackgroundColor(myColor);

        firstButton.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                if (myColor == Color.WHITE)
                    myColor = Color.BLACK;
                else if (myColor == Color.BLACK)
                    myColor = Color.WHITE;

                myView.setBackgroundColor(myColor);
            }

        });
    }

    @Override
    // this method is called before android trashes and recreates your activity
    protected void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt("COLOR", myColor);
    }
}

Alternatively you could do it the cheap-dumb-ass way: Locking the screen. add the 'android:configChanges' attribute to your activity.

 <activity
    android:name="UserIdActivity"
    android:label="@string/app_name"
    android:configChanges="orientation" />

And implement the 'onConfigurationChanged' callback to do nothing

public void onConfigurationChanged ( Configuration newConfig)
{
}