Question

I have a checkbox on my activity. I’m wondering how to make its state stay the same (checked/unchecked) everytime I open my app.

Answer 1

You can use SharedPreferences to implement CheckBox which retains its state even if application is closed.

• When user checks/un-check CheckBox.Save it’s state in Shared
  Preferences.
• Whenever user Opens your activity. Read previously saved value from
  Shared-Preferences, and set the state of check box.

Here is an Example code to for Saving state of checkbox even if app is closed.

public class TestActivity extends Activity{
    CheckBox checkBox = null;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        checkBox = (CheckBox) findViewById(R.id.my_check_box);
        boolean isChecked = getBooleanFromPreferences("isChecked");
        Log.i("start",""+isChecked);
        checkBox.setChecked(isChecked);
        checkBox.setOnCheckedChangeListener(new OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton view, boolean isChecked) {
                Log.i("boolean",""+isChecked);
                TestActivity.this.putBooleanInPreferences(isChecked,"isChecked");
            }
        });
    }
    public void putBooleanInPreferences(boolean isChecked,String key){
        SharedPreferences sharedPreferences = this.getPreferences(Activity.MODE_PRIVATE);
        SharedPreferences.Editor editor = sharedPreferences.edit();
        editor.putBoolean(key, isChecked);
        editor.commit();        
    }
    public boolean getBooleanFromPreferences(String key){
        SharedPreferences sharedPreferences = this.getPreferences(Activity.MODE_PRIVATE);
        Boolean isChecked = sharedPreferences.getBoolean(key, false);
        return isChecked;       
    }
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <CheckBox
        android:id="@+id/my_check_box"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>

</LinearLayout>