Q:

How can I maintain the state of a CheckBox even after navigating to different activities in android?

I'm a newbie in Android development. 
Let me explain my problem.
I've have a checkbox and a Button in my Main activity. When I Check(that is, enable) my checkbox and Click my Button below it, I'll be moving to another activity and as I click a button in the second activity, I come back to my main Activity. My problem is when I come back, the Checkbox remains UnChecked or Disabled. What do I do to retain its state even after coming back from the second activity? Please Help.
The CheckBox part of XML layout is:
<CheckBox
    android:id="@+id/ckBxAll"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="ON" />

Skeleton code for Main activity:
Public class TestActivity extends Activity {
public void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
LayoutInflater mInflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
View mMainView = mInflater.inflate(R.layout.main, null);        
setContentView(mMainView);
 Enable_chkbox = (CheckBox)mMainView.findViewById(R.id.ckBxAll);
if(b_onResume==true)
    {
      Enable_chkbox.setChecked(b_onResume);
   }
Enable_chkbox.setOnCheckedChangeListener(new OnCheckedChangeListener() {

            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                // TODO Auto-generated method stub

//do something

        });//Enable_chkbox
Compose_btn=(Button)findViewById(R.id.btnCompose);
        Compose_btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent gotoComposeMessage=new Intent(TestActivity.this,ComposeMessage.class);
                startActivity(gotoComposeMessage);
            }
        });
}
@Override
    protected void onResume() {
      super.onResume();
     b_onResume=  Enable_chkbox.isChecked();

    }
   @Override
    protected void onDestroy() {
        // TODO Auto-generated method stub
        super.onDestroy();
        unregisterReceiver(myreceiver);
        this.finish();
      }
    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK) {
            moveTaskToBack(true);
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }
    @Override
    public void onSaveInstanceState(Bundle savedInstanceState) {
       super.onSaveInstanceState(savedInstanceState);
       savedInstanceState.putBoolean("Enable_chkbox",true);       

    }
    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onRestoreInstanceState(savedInstanceState);
        boolean myBoolean = savedInstanceState.getBoolean("Enable_chkbox");
    }  

}

My Second Activity:
public class ComposeMessage extends Activity{
    Button SaveSMS_btn;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.composemessage);
        SaveSMS_btn=(Button)findViewById(R.id.btnSave);
        SaveSMS_btn.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                Intent gotoHome=new Intent(getApplicationContext(),BlockTestActivity.class);
                Bundle BundleToCarryMessage = new Bundle();
                EditText EnterSMS_edt=(EditText)findViewById(R.id.edtEnterSMS);
                BundleToCarryMessage.putString("Message", EnterSMS_edt.getText().toString());
                gotoHome.putExtras(BundleToCarryMessage);
                startActivity(gotoHome);
            }
        });

    }

}

The XML file used in the second activity:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <EditText
        android:id="@+id/edtEnterSMS"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="textMultiLine" >

        <requestFocus />
    </EditText>

    <Button
        android:id="@+id/btnSave"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Save" />

</LinearLayout>

A:

There is another way.
You need to override onSaveInstanceState(Bundle savedInstanceState) and write the application state values you want to change to the Bundle parameter like this:
The next code is for saving the check box state, before moving to the second activity:
@Override
public void onSaveInstanceState(Bundle savedInstanceState) {

  savedInstanceState.putBoolean("MyCheckBox", enable);

  super.onSaveInstanceState(savedInstanceState);
}

And this is when you restore the check box state:
@Override
public void onRestoreInstanceState(Bundle savedInstanceState) {
  super.onRestoreInstanceState(savedInstanceState);

  boolean myBoolean = savedInstanceState.getBoolean("MyCheckBox");

}

EDIT: 
public class TestActivity extends Activity implements OnCheckedChangeListener, OnClickListener  {

        private CheckBox Enable_chkbox;
        private View mMainView;
        private Button Compose_btn;
        private boolean myBoolean = false;;

        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            LayoutInflater mInflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
            mMainView = mInflater.inflate(R.layout.main, null);        
            setContentView(mMainView);
            initView();
        }

        private void initView(){

             Enable_chkbox = (CheckBox)mMainView.findViewById(R.id.ckBxAll);
             Enable_chkbox.setOnCheckedChangeListener(this);
             Compose_btn=(Button)mMainView.findViewById(R.id.btnCompose);
             Compose_btn.setOnClickListener(this);
        }

        @Override
        protected void onResume() {
          super.onResume();
          Enable_chkbox.setChecked(myBoolean);

        }

        @Override
        public void onSaveInstanceState(Bundle savedInstanceState) {
           super.onSaveInstanceState(savedInstanceState);
           savedInstanceState.putBoolean("Enable_chkbox", Enable_chkbox.isChecked());      
        }

        @Override
        protected void onRestoreInstanceState(Bundle savedInstanceState) {
            super.onRestoreInstanceState(savedInstanceState);
            myBoolean = savedInstanceState.getBoolean("Enable_chkbox");
        }

        @Override
        public void onClick(View arg0) {
            //do something
        }

        @Override
        public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
            //do something
        }  
}

'
Hope it helps.

