Android: Keep username in session until logout

Question

I'm having hard time trying to figure out how to use SharedPreferences to store the username in the phone and stay in session until logout. I also need to know how at the same time its in session it will send the username out with the data the user click on within the listview. Below are the codes I am using and would like to know where and what code to put in order to acheive this. As login it will go to the menu and stay at the menu (avoid the backbutton from going back to the login screen) Every menu have a logout item which will go back to the login screen.

The previous questions i've looked at are this and this

Logcat Detail

05-26 10:42:19.146: WARN/KeyCharacterMap(26071): Using default keymap: /system/usr/keychars/qwerty.kcm.bin
05-26 10:42:23.926: DEBUG/AndroidRuntime(26071): Shutting down VM
05-26 10:42:23.926: WARN/dalvikvm(26071): threadid=3: thread exiting with uncaught exception (group=0x40013140)
05-26 10:42:23.926: ERROR/AndroidRuntime(26071): Uncaught handler: thread main exiting due to uncaught exception
05-26 10:42:23.936: ERROR/AndroidRuntime(26071): java.lang.NullPointerException
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.merrill2.Login$1.onClick(Login.java:42)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.View.performClick(View.java:2232)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.View.onTouchEvent(View.java:3905)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.widget.TextView.onTouchEvent(TextView.java:6414)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.View.dispatchTouchEvent(View.java:3421)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:906)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:906)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:906)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:906)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1707)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1197)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.app.Activity.dispatchTouchEvent(Activity.java:1993)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1691)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.view.ViewRoot.handleMessage(ViewRoot.java:1533)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.os.Handler.dispatchMessage(Handler.java:99)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.os.Looper.loop(Looper.java:123)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at android.app.ActivityThread.main(ActivityThread.java:3992)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at java.lang.reflect.Method.invokeNative(Native Method)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at java.lang.reflect.Method.invoke(Method.java:521)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:540)
05-26 10:42:23.936: ERROR/AndroidRuntime(26071):     at dalvik.system.NativeStart.main(Native Method)
05-26 10:42:23.946: INFO/Process(899): Sending signal. PID: 26071 SIG: 3
05-26 10:42:23.956: INFO/dalvikvm(26071): threadid=7: reacting to signal 3
05-26 10:42:23.966: INFO/dalvikvm(26071): Wrote stack trace to '/data/anr/traces.txt'
05-26 10:42:25.646: DEBUG/dalvikvm(25722): GC freed 973 objects / 63040 bytes in 93ms
05-26 10:42:27.777: DEBUG/DispatchService(945): Handled message = TIMED_SERVICE_UNMASK
05-26 10:42:29.856: DEBUG/DispatchService(945): DISPATCH SERVICE getIdenPacketDataState: returning: 4
05-26 10:42:29.876: INFO/iDENWAPReceiver(953): Received a android.intent.action.ANY_DATA_STATE

Login.java

public class Login extends Activity {
    protected static final SharedPreferences settings = null;
    private EditText etUsername;
    private Button btnLogin;
    private Button btnCancel;
    private TextView lblResult;
    /** Called when the activity is first created. */
    //@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.login);

        etUsername = (EditText)findViewById(R.id.username);
        btnLogin = (Button)findViewById(R.id.login_button);
        btnCancel = (Button)findViewById(R.id.cancel_button);
        lblResult = (TextView)findViewById(R.id.result);

        btnLogin.setOnClickListener(new OnClickListener() {
            //@Override
            public void onClick(View v) {
            // Check Login
            String username = etUsername.getText().toString();

            SharedPreferences prefs = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
            SharedPreferences.Editor editor = settings.edit();
            editor.putString("username", username);

            if(username.equals("1111")){
                lblResult.setText("Login successful.");

                //startActivity(new Intent(this, Activity2.class));


                Intent i = new Intent(getApplicationContext(), Customer.class);
                startActivity(i);

if i take out the line below:

protected static final SharedPreferences settings = null;

i put this:

btnLogin.setOnClickListener(new OnClickListener() {
            private SharedPreferences settings;

'settings' is giving error so i had to use one of those line mentioned above

Answer 1

When the user logs in successfully, add the user's username to the SharedPreference for your application.

SharedPreferences settings = getSharedPreferences("MyPrefsFile", 0);
SharedPreferences.Editor editor = settings.edit();
editor.putString("username", username);

Every time the user opens the app, check to see if the "userID" preference is set. If it is then he is logged in. otherwise show the Login screen. When the user logs out, delete the "username" entry from the shared prefs.

I also need to know how at the same time its in session it will send the username out with the data the user click on within the listview

You will have access to the user's ID through that shared pref so you are able to use it whenever you need it. The Android framework does not do that for you but it's a simple task for you to do.

Answer 2

To add the user just do:

import android.preference.PreferenceManager;
....
SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.putString("username", username);

And to delete it, in Logout:

SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
SharedPreferences.Editor editor = settings.edit();
editor.remove("username");

This way you make sure that the user only lasts for one session, until it logs out. You should make a check (just in case), when you open your app, to see if there is an username already set from a previous session if something wrong happened.

And as for passing the data in a ListView, you have to do it by hand. SharedPreference framework takes care of everything else.

Answer 3

I think this example should be very helpful.

http://www.androidhive.info/2012/08/android-session-management-using-shared-preferences/

The main class is here:

public class SessionManager {
    // Shared Preferences
    SharedPreferences pref;

    // Editor for Shared preferences
    Editor editor;

    // Context
    Context _context;

    // Shared pref mode
    int PRIVATE_MODE = 0;

    // Sharedpref file name
    private static final String PREF_NAME = "AndroidHivePref";

    // All Shared Preferences Keys
    private static final String IS_LOGIN = "IsLoggedIn";

    // User name (make variable public to access from outside)
    public static final String KEY_NAME = "name";

    // Email address (make variable public to access from outside)
    public static final String KEY_EMAIL = "email";

    // Constructor
    public SessionManager(Context context){
        this._context = context;
        pref = _context.getSharedPreferences(PREF_NAME, PRIVATE_MODE);
        editor = pref.edit();
    }

    /**
     * Create login session
     * */
    public void createLoginSession(String name, String email){
        // Storing login value as TRUE
        editor.putBoolean(IS_LOGIN, true);

        // Storing name in pref
        editor.putString(KEY_NAME, name);

        // Storing email in pref
        editor.putString(KEY_EMAIL, email);

        // commit changes
        editor.commit();
    }   

    /**
     * Check login method wil check user login status
     * If false it will redirect user to login page
     * Else won't do anything
     * */
    public void checkLogin(){
        // Check login status
        if(!this.isLoggedIn()){
            // user is not logged in redirect him to Login Activity
            Intent i = new Intent(_context, LoginActivity.class);
            // Closing all the Activities
            i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

            // Add new Flag to start new Activity
            i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

            // Staring Login Activity
            _context.startActivity(i);
        }

    }



    /**
     * Get stored session data
     * */
    public HashMap<String, String> getUserDetails(){
        HashMap<String, String> user = new HashMap<String, String>();
        // user name
        user.put(KEY_NAME, pref.getString(KEY_NAME, null));

        // user email id
        user.put(KEY_EMAIL, pref.getString(KEY_EMAIL, null));

        // return user
        return user;
    }

    /**
     * Clear session details
     * */
    public void logoutUser(){
        // Clearing all data from Shared Preferences
        editor.clear();
        editor.commit();

        // After logout redirect user to Loing Activity
        Intent i = new Intent(_context, LoginActivity.class);
        // Closing all the Activities
        i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);

        // Add new Flag to start new Activity
        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

        // Staring Login Activity
        _context.startActivity(i);
    }

    /**
     * Quick check for login
     * **/
    // Get Login State
    public boolean isLoggedIn(){
        return pref.getBoolean(IS_LOGIN, false);
    }
}