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A view will automatically save its instance state if it has a unique id, but if you press back the data will still be destroyed. SharedPreferences are used to store key-value pairs for our apps. Typical uses are to save the user's name, keep track of what theme the user prefers, store a counter of how many times the user signed on, or keep track of the high score.

<B>First, start off by declaring a constant for the file name. Then declare a constant for the key we'll require:</B>

private static final String PREFS_FILE = "com.company.preferences";   //.preferences at the end is standard naming convention

private static final String KEY_CHECKBOX = "key_checkbox";

<B>Second, declare SharedPreferences and an Editor field.</B>

private SharedPreferences mSharedPreferences;
private SharedPreferences.Editor mEditor;

<B>Third, initialize mSharedPreferences and mEditor in onCreate method.<B>

mSharedPreferences = getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE);
mEditor = mSharedPreferences.edit();

<B>Forth, Override onPause method. Save the value in a Boolean and apply</B>

mEditor.putBoolean(KEY_CHECKBOX, mCheckBox.isChecked());
mEditor.apply();

<B>Lastly, Retrieve the saved value in onCreate and set the state of the CheckBox</B>

Boolean isCheckBoxChecked = mSharedPreferences.getBoolean(KEY_CHECKBOX, false);
mCheckBox.setChecked(isCheckBoxChecked);

<B>Example 1: uses a checkbox </B>

import android.view.View;
import android.os.Bundle;

public class MainActivity extends Activity {
    
  private static final String PREFS_FILE= "com.company.preferences";
  private static final String KEY_CHECKBOX= "key_checkbox";
  
  private SharedPreferences mSharedPreferences;
  private SharedPreferences.Editor mEditor;
  public CheckBox mCheckBox;

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

    mCheckBox = (CheckBox) findViewById(R.id.checkBox);
    mSharedPreferences = getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE);
    mEditor = mSharedPreferences.edit();

    Boolean isCheckBoxChecked = mSharedPreferences.getBoolean(KEY_CHECKBOX, false);
    mCheckBox.setChecked(isCheckBoxChecked);
  }
  @Override
  protected void onPause(){
    super.onPause();
    
    mEditor.putBoolean(KEY_CHECKBOX, mCheckBox.isChecked());
    mEditor.apply();
  }
}
 



<B>Example 2: uses an editText</B>

public class MainActivity extends AppCompatActivity{
    private static final String PREFS_FILE = "com.company.preferences";
    private static final String KEY_EDIITTEXT = "key_edittext";
    private SharedPreferences.Editor mEditor;
    private SharedPreferences mSharedPreferences;
    private EditText mEditText;

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

        mEditText = (EditText) findViewById(R.id.editText);
        mSharedPreferences = getSharedPreferences(PREFS_FILE, Context.MODE_PRIVATE);
        mEditor = mSharedPrefernces.edit();

        String editTextString = mSharedPreferences.getString(KEY_EDITTEXT, ""); //pass in key and empty string for default when string isn't found
        mEditText.setText(editTextString);   //update our editText
    }

    @Override
    protected void onPause(){
        super.onPause();
        
        mEditor.putString(KEY_EDITTEXT, mEditText.getText().toString());
        mEditor.apply();
    }
}

To clear to default values, you can use the clear method of a sharedPreferences editor Object. Also, can use the remove() and pass in a key to remove just one value (don't forget apply() to update value).