Logout clear SharedPreferences

Question

I have a login page that saves username and password to SharedPreferences. I have another Activity class that includes a logout button. I want to clear SharedPreferences when I click the logout button. The problem is that I don't get the SharedPreferences from this class. How can I get the SharedPreferences?

LoginPage

public class MainActivity extends Activity { public SharedPreferences.Editor loginPrefsEditor;     public  SharedPreferences loginPreferences;     private Boolean saveLogin; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);         setContentView(R.layout.activity_main);      name = (EditText) findViewById(R.id.et_Username);         pass = (EditText) findViewById(R.id.et_Password);         login = (Button) findViewById(R.id.bt_Login);           loginPreferences = getSharedPreferences("loginPrefs", MODE_PRIVATE);          loginPrefsEditor = loginPreferences.edit();           saveLogin = loginPreferences.getBoolean("saveLogin", false);           if (saveLogin == true) {                 name.setText(loginPreferences.getString("username", ""));                 pass.setText(loginPreferences.getString("password", ""));                }          login.setOnClickListener(new OnClickListener()         {             @Override             public void onClick(View v) {                  name1 = name.getText().toString();                  pass1 = pass.getText().toString();                //new Thread (new Task()).start();                     loginPrefsEditor.putBoolean("saveLogin", true);                     loginPrefsEditor.putString("username", name1);                     loginPrefsEditor.putString("password", pass1);                     loginPrefsEditor.commit();                  new myAsyncTask().execute();             }         }); } 

Logout Button in AnotherActivity

 logout.setOnClickListener(new View.OnClickListener() {              @Override             public void onClick(View view) {                 // Launching News Feed Screen                  Intent i = new Intent(getApplicationContext(), MainActivity.class);                 startActivity(i);             }         }); 

Answer 1

Try this !

logout.setOnClickListener(new View.OnClickListener() {          @Override         public void onClick(View view) {             // Launching News Feed Screen               SharedPreferences preferences =getSharedPreferences("loginPrefs",Context.MODE_PRIVATE);              SharedPreferences.Editor editor = preferences.edit();              editor.clear();              editor.apply();              finish();  }); 

Answer 2

I think you have a trouble in understanding Shared preferences in android .

According to official documentation

To get a SharedPreferences object for your application, use one of two methods:

getSharedPreferences() - Use this if you need multiple preferences files identified by name, which you specify with the first parameter.

getPreferences() - Use this if you need only one preferences file for your Activity. Because this will be the only preferences file for your Activity, you don't supply a name.

You should have a Context for using both the above methods .

Also Shared preferences are stored asa key value pair , so clearing should mean that you set the values to some empty string.

For more details , and better explanation you can read here http://developer.android.com/guide/topics/data/data-storage.html#pref and http://www.vogella.com/tutorials/AndroidFileBasedPersistence/article.html

Hope this will help.

Cheers!