Logout from the application Android

Question

I have tried to logout from my app when the user clicks on Logout.It is working fine in case the user after login without closing the app if he doed logout .Then it is working properly.Back button will be ineffective in case to show again the login page after doing login But when the user after login closes the application and then he does logout the login page is not showing it is showing a blank page to me

Code

public class AppState {
    private static AppState singleInstance;

    private boolean isLoggingOut;

    private AppState() {
    }

    public static AppState getSingleInstance() {
        if (singleInstance == null) {
            singleInstance = new AppState();
        }
        return singleInstance;
    }

    public boolean isLoggingOut() {
        return isLoggingOut;
    }

    public void setLoggingOut(boolean isLoggingOut) {
        this.isLoggingOut = isLoggingOut;
    }
}

OnClick of logout

logout.setOnClickListener(new OnClickListener() {
    @Override
            public void onClick(View arg0) {
                SharedPreferences myPrefs = getSharedPreferences("MY",
                        MODE_PRIVATE);
                SharedPreferences.Editor editor = myPrefs.edit();
                editor.clear();
                editor.commit();
                AppState.getSingleInstance().setLoggingOut(true);
                Log.d(TAG, "Now log out and start the activity login");
                Intent intent = new Intent(HomePage.this,
                        LoginPage.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent);

            }
        });

IN the LoginActivity

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        if (requestCode == MAIN_ACTIVITY_REQUEST_CODE) {

            if (!AppState.getSingleInstance().isLoggingOut()) {
                finish();
            } else {
                AppState.getSingleInstance().setLoggingOut(false);
                super.onActivityResult(requestCode, resultCode, data);
            }
        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }
    }

    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);

    }

Please suggest me what i have done wrong in this

After Your Suggestions of Vivek Bhusal i tried to use sharedpref

HomePage logout Clicked

logout.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View arg0) {
                SharedPreferences myPrefs = getSharedPreferences("Activity",
                        MODE_PRIVATE);
                SharedPreferences.Editor editor = myPrefs.edit();
                editor.clear();
                editor.commit();
                //AppState.getSingleInstance().setLoggingOut(true);
                setLoginState(true);
                Log.d(TAG, "Now log out and start the activity login");
                Intent intent = new Intent(HomePage.this,
                        LoginPage.class);
                intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
                startActivity(intent);

            }
        });

private void setLoginState(boolean status) {
        SharedPreferences sp = getSharedPreferences("LoginState",
                MODE_PRIVATE);
            SharedPreferences.Editor ed = sp.edit();
            ed.putBoolean("setLoggingOut", status);
            ed.commit();
    }

On the Login Page

protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        SharedPreferences sp = getSharedPreferences("LoginState",
                MODE_PRIVATE);
        boolean stateValue  = sp.getBoolean("setLoggingOut", false);
        if (requestCode == MAIN_ACTIVITY_REQUEST_CODE) {

            if (!stateValue) {
                finish();
            } else {
                //AppState.getSingleInstance().setLoggingOut(false);
                updateLoginState(false);
                super.onActivityResult(requestCode, resultCode, data);
            }
        } else {
            super.onActivityResult(requestCode, resultCode, data);
        }
    }

Still the same issue showing a blank screen when i again restart the app and then do the logout.

Answer 1

You can use the SharedPreferences class in android. It can use to save the value and load it again. This is the docs and tutorial.

Answer 2

case R.id.drawer_item_logout: //name of logout button

                    AlertDialog.Builder builder=new AlertDialog.Builder(Home.this); //Home is name of the activity
                    builder.setMessage("Do you want to exit?");
                    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int id) {

                            finish();
                            Intent i=new Intent();
                            i.putExtra("finish", true);
                            i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP); // To clean up all activities
                           //startActivity(i);
                            finish();

                        }
                    });

                    builder.setNegativeButton("CANCEL", new DialogInterface.OnClickListener() {
                        @Override
                        public void onClick(DialogInterface dialog, int id) {
                            dialog.cancel();
                        }
                    });

                        AlertDialog alert=builder.create();
                    alert.show();


                    break;

Answer 3

The onNewIntent() should be used in singleTop activities. Beside that, I don't see a startActivityForResult() call to Login Page/Activity.

Blank page means your activity has not setup its view (with setContentView()).

I would suggest moving your "logging out" checks and setContentView() to onResume() of the Login Page/Activity.

Answer 4

This code is used for logout from app

        Intent logoutintent = new Intent(this, LoginActivity.class);
        startActivity(logoutintent);
        SharedPreferences loginSharedPreferences;
        loginSharedPreferences = getSharedPreferences(
                LoginActivity.MyPREFERENCES, Context.MODE_PRIVATE);
        Editor editor = loginSharedPreferences.edit();
        editor.putString("UniqueId", "");
        editor.commit();
        finish();

Answer 5

I noticed that your logout button does start the Login activity but does not finish the Home Page activity. To close the Home Page:

Intent intent = new Intent(HomePage.this, LoginPage.class);
startActivity(intent);
finish()  // This call is missing.

To open it, from the Login Page:

Intent intent = new Intent(LoginPage.this, HomePage.class);
startActivity(intent);
finish()

Finish one activity after you start another. This way your task stack will have only one activity, i.e., no back history. Check the example app posted by Vivek Bhusal.

I suggest reading this SO question, the accepted answer, and also this answer for more ideas on how to perform logout and some caveats with Intent.FLAG_ACTIVITY_CLEAR_TOP, which, in your case, is not really necessary.

Answer 6

  if (!AppState.getSingleInstance().isLoggingOut()) {

do you think this statement correct?? because i saw when this condition is true you finish the activity i think that means logout but isLoggingOut should be true however you check if it is false you call finish. am i right??