Android Application crashes when going from an activity to another using intent

Question

I am trying for hours to do an extremely simple thing, but for some reason it doesn't work... I'm trying to go from an activity that is used for Log in, to another activity that is used for signing up. The rest of the code works perfectly, but whenever I press the textview that supposes to bring me to the Registration screen, the app crashes. I tried everything, even to use a button instead of textview, and many ways of intents I found online, with "finish" and without "finish", but nothing worked, do you guys have any idea what went wrong? The Activity is added to the manifest. Thank you!

public class LoginActivityU extends AppCompatActivity implements View.OnClickListener {

String Uname, Pass;
Button loginButton;
EditText userEt;
EditText passwordEt;
HashMap<String, String> hashMap;
ProgressDialog p;
Boolean check = false;
SharedPreferences sp;
SharedPreferences.Editor editor;
TextView tvSignUp;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);
    sp=this.getSharedPreferences("LocalLogInData", 0);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    Intent intent = getIntent();
    setSupportActionBar(toolbar);
    loginButton = (Button) findViewById(R.id.btn_login);
    userEt = (EditText) findViewById(R.id.input_uname);
    passwordEt = (EditText) findViewById(R.id.input_password);
    tvSignUp = (TextView) findViewById(R.id.link_signup);
    loginButton.setOnClickListener(this);
    tvSignUp.setOnClickListener(this);
    Uname = sp.getString("Uname", null);
    Pass = sp.getString("Pass", null);
    Log.d("dds", Uname + Pass);
    if (Uname != null && Pass != null)
    {
        userEt.setText(Uname);
        passwordEt.setText(Pass);

        hashMap = new HashMap<String, String>();
        hashMap.put("username",userEt.getText().toString());
        hashMap.put("password",passwordEt.getText().toString());
        Login login=new Login();
        login.execute("https://example.com");
        if(check == false)
        {
            editor=sp.edit();
            editor.remove("Uname");
            editor.remove("Pass");
            editor.commit();

        }
    }

}


@Override
public void onClick(View view) {
    if (loginButton.isPressed())
    {
        hashMap = new HashMap<String, String>();
        hashMap.put("username",userEt.getText().toString());
        hashMap.put("password",passwordEt.getText().toString());

        editor=sp.edit();
        editor.putString("Uname",userEt.getText().toString());
        editor.putString("Pass",passwordEt.getText().toString());


        Login login=new Login();
        login.execute("https://peulibrary.co.il/api/user/generate_auth_cookie/");
        editor.commit();
    }
    else if (tvSignUp.isPressed())
    {
        Intent intent = new Intent(this, SignUpActivity.class);
        startActivity(intent);
        finish();
    }
}

Log of crash:

02-03 14:35:51.661 10836-10836/com.example.negev.peulibraryv201 E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.negev.peulibraryv201, PID: 10836 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.example.example/com.example.example.example.SignUpActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2476) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$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$MethodAndArgsCaller.run(ZygoteInit.java:726) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)' on a null object reference at com.example.negev.peulibraryv201.SignUpActivity.onCreate(SignUpActivity.java:22) 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)

have you added the second activity into your manifest file? – Hector Feb 03 '18 at 14:32 — Hector, Feb 03 '18 at 14:32
In studio you can see logs please attach that also – Renjith Thankachan Feb 03 '18 at 14:33 — Renjith Thankachan, Feb 03 '18 at 14:33
Yes of course it's added to the manifest. – NegNeg64 Feb 03 '18 at 14:34 — NegNeg64, Feb 03 '18 at 14:34

score 0 · Answer 1 · answered Feb 03 '18 at 14:40

seeing the logs it is clear that the Problem should be in your signup activity.

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.design.widget.FloatingActionButton.setOnClickListener(android.view.View$OnClickListener)'

indicates that there is a widget you are referring is not initialized or null

score 0 · Accepted Answer · answered Feb 03 '18 at 14:42

0

Looking at the crash log, it seems that you are attaching a click listener to your FloatingActionButton before instantiating it. Please make sure that you call findViewById and instantiate the view first, and only call setOnClickListener after. The problem is in SignUpActivity.

answered Feb 03 '18 at 14:42

Robert K.

1,043
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20

Wow thanks! haven't realized that... – NegNeg64 Feb 03 '18 at 14:47

Android Application crashes when going from an activity to another using intent

2 Answers2