Android Studio Shared Preference Application Stopped Working

Question

My mobile application stopped working after I added the checking for ip section in my onCreate function to make registered users bypass the login screen. This might have something to do with the variable declarations but I'm still not sure what's going on.

private EditText etUsername;
private EditText etPassword;
private EditText etIpAddress;
private Button btnLogin;

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    String username = etUsername.toString();
    String password = etPassword.toString();
    String ipAddress = etIpAddress.toString();

    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(LoginActivity.this);
    if (sharedPreferences.contains("ip")) {
        performLogin(username, password, sharedPreferences.getString("ip", ipAddress));
    }

    // declaring variebles
    etUsername = (EditText)findViewById(R.id.etUsername);
    etPassword= (EditText)findViewById(R.id.etPassword);
    btnLogin = (Button)findViewById(R.id.btnLogin);
    etIpAddress = (EditText) findViewById(R.id.etIpAddress);

    // setting up things for login button
    btnLogin.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            String ipAddress = etIpAddress.getText().toString();

            SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(LoginActivity.this);

            sharedPreferences.edit()
                    .putString("ip", ipAddress)
                    .apply();

            String username = etUsername.getText().toString().trim();
            String password = etPassword.getText().toString().trim();

            performLogin(username, password, ipAddress);
        }
    });
}

private void performLogin(String username, String password, String ipAddress) {
    try {
        Device.login(username, password, ipAddress, this);
    } catch (JSONException e) {
        onLoginFailure(e);
    }
}

Logcat:

06-06 16:40:11.408 4000-4000/com.itemlocator.findit E/AndroidRuntime: FATAL EXCEPTION: main
                                                                      Process: com.itemlocator.findit, PID: 4000
                                                                      java.lang.RuntimeException: Unable to start activity ComponentInfo{com.itemlocator.findit/com.itemlocator.findit.LoginActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.widget.EditText.toString()' on a null object reference
                                                                          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416)
                                                                          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476)
                                                                          at android.app.ActivityThread.-wrap11(ActivityThread.java)
                                                                          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
                                                                          at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                          at android.os.Looper.loop(Looper.java:148)
                                                                          at android.app.ActivityThread.main(ActivityThread.java:5417)
                                                                          at java.lang.reflect.Method.invoke(Native Method)
                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
                                                                       Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.widget.EditText.toString()' on a null object reference
                                                                          at com.itemlocator.findit.LoginActivity.onCreate(LoginActivity.java:32)
                                                                          at android.app.Activity.performCreate(Activity.java:6237)
                                                                          at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107)
                                                                          at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2369)
                                                                          at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) 
                                                                          at android.app.ActivityThread.-wrap11(ActivityThread.java) 
                                                                          at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344) 
                                                                          at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                          at android.os.Looper.loop(Looper.java:148) 
                                                                          at android.app.ActivityThread.main(ActivityThread.java:5417) 
                                                                          at java.lang.reflect.Method.invoke(Native Method) 
                                                                          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
                                                                          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 

Answer 1

In Login Screen put this code after login_WS call

`SharedPreferences pref = getActivity().getSharedPreferences(MyPre, Context.MODE_PRIVATE); Editor editor = pref.edit(); editor.putString(PARAMS.KEY_PROFILE_DATA, jsonObject.get("data").toString()); editor.putString(PARAMS.KEY_USER_ID, ConstantData.USER_ID); editor.putBoolean(PARAMS.KEY_STAY_LOGGED_IN, true); editor.commit();

In splash screen put this code

` private Runnable mRunnable = new Runnable() {

    @Override
    public void run() {

        pref = getSharedPreferences(MyPre, Context.MODE_PRIVATE);

        //Log.i("splash","Boolen value 1" + pref.getBoolean(PARAMS.KEY_STAY_LOGGED_IN,false));

         is = Boolean.parseBoolean(String.valueOf((pref.getBoolean(PARAMS.KEY_STAY_LOGGED_IN, false))));

        Log.i("splash","Boolen value 2" + is);

        if (is) {

            Intent mIntent = new Intent(SplashScreenActivity.this, MainActivity.class);
            startActivity(mIntent);
            // overridePendingTransition(R.anim.enter, R.anim.no_anim);
            finish();

        } else {

            Intent mIntent = new Intent(SplashScreenActivity.this, LoginActivity.class);
            startActivity(mIntent);
            overridePendingTransition(R.anim.enter, R.anim.no_anim);
            finish();

        }`

Hope this works for you

Answer 2

String username = etUsername.toString();
String password = etPassword.toString();
String ipAddress = etIpAddress.toString();

will produce NullPointerExceptions since your EditTexts are not initialized yet. You have to call first:

etUsername = (EditText)findViewById(R.id.etUsername);
etPassword= (EditText)findViewById(R.id.etPassword);
btnLogin = (Button)findViewById(R.id.btnLogin);
etIpAddress = (EditText) findViewById(R.id.etIpAddress);

Also I think you mean

String username = etUsername.getText().toString();