navigate to another page using the button: Unable to start activity ComponentInfo java.lang.NullPointerException

Question

I'm developing a demo app when i login it will navigate to another page.

Here using button i'm trying to navigate to other page

Main activity

public class WelcomeActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_welcome);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        Button ibsignin = (Button) findViewById(R.id.ibsignin);
        ibsignin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent (v.getContext(), Register.class);
                startActivity(intent);
            }
        });
    }
}

I have defined button code in xml file still i'm getting null pointer exception.

XML file

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.example.nandan.uschedule.WelcomeActivity"
    android:background="@drawable/edit1">

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="75dp"
        android:id="@+id/welcome"
        android:background="@drawable/minnesota"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

    </LinearLayout>

    <LinearLayout
        android:orientation="vertical"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/linearLayout"
        android:clickable="false"
        android:layout_alignParentTop="true"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true">

        <EditText
            android:layout_width="350dp"
            android:layout_height="wrap_content"
            android:id="@+id/ibusername"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_gravity="center"
            android:layout_marginBottom="200dp"
            android:layout_marginTop="225dp"
            android:inputType="textEmailAddress|text"
            android:hint="User name/ Email Address"
            android:textColor="#000000"
            android:textStyle="normal" />

        <EditText
            android:layout_width="350dp"
            android:layout_height="wrap_content"
            android:inputType="textPassword|text"
            android:ems="10"
            android:id="@+id/ibpassword"
            android:hint="Password"
            android:layout_gravity="center"
            android:layout_marginTop="-200dp"
            android:textColor="#000000" />

        <CheckBox
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Remember me"
            android:id="@+id/cbRememberme"
            android:hint="Remember me"
            android:layout_gravity="center" />

        <Button
            android:layout_width="250dp"
            android:layout_height="38dp"
            android:text="Sign in"
            android:id="@+id/ibsingin"
            android:layout_gravity="center"
            android:background="#4D306A" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="40dp"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Do not have an account yet?"
            android:id="@+id/havenoaccount"
            android:layout_gravity="center"
            android:textColor="#000000"
            android:paddingTop="12dp"
            android:textSize="20dp" />

        <Button
            android:layout_width="250dp"
            android:layout_height="38dp"
            android:text="Sign up"
            android:id="@+id/ibsignup"
            android:layout_gravity="center"
            android:background="#4D306A" />

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:textAppearance="?android:attr/textAppearanceMedium"
            android:text="Forgot Password?"
            android:id="@+id/ibforgotpwd"
            android:layout_gravity="center"
            android:textColor="#000000"
            android:textSize="20dp"
            android:clickable="true" />

    </LinearLayout>

</RelativeLayout>

my logcat

 Process: com.example.nandan.uschedule, PID: 2487
  java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nandan.uschedule/com.example.nandan.uschedule.WelcomeActivity}: java.lang.NullPointerException
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
      at android.app.ActivityThread.access$800(ActivityThread.java:135)
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
      at android.os.Handler.dispatchMessage(Handler.java:102)
      at android.os.Looper.loop(Looper.java:136)
      at android.app.ActivityThread.main(ActivityThread.java:5001)
      at java.lang.reflect.Method.invokeNative(Native Method)
      at java.lang.reflect.Method.invoke(Method.java:515)
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
      at dalvik.system.NativeStart.main(Native Method)
   Caused by: java.lang.NullPointerException
      at com.example.nandan.uschedule.WelcomeActivity.onCreate(WelcomeActivity.java:27)
      at android.app.Activity.performCreate(Activity.java:5231)
      at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
      at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
      at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233) 
      at android.app.ActivityThread.access$800(ActivityThread.java:135) 
      at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
      at android.os.Handler.dispatchMessage(Handler.java:102) 
      at android.os.Looper.loop(Looper.java:136) 
      at android.app.ActivityThread.main(ActivityThread.java:5001) 
      at java.lang.reflect.Method.invokeNative(Native Method) 
      at java.lang.reflect.Method.invoke(Method.java:515) 
      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
      at dalvik.system.NativeStart.main(Native Method)

ibsignin.setOnClickListener(new View.OnClickListener() { @CommonsWare — nandan dasari, Mar 17 '16 at 17:20

score 3 · Answer 1 · answered Mar 17 '16 at 17:18

3

I don't know which line is 27, but it's most likely the NPE comes from here:

Button ibsignin = (Button) findViewById(R.id.ibsignin);

Make sure your button is in your XML layout and that it is called ibsignin.

answered Mar 17 '16 at 17:18

Francesc

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but its already there in the code, and i'm completely new to android – nandan dasari Mar 17 '16 at 17:27
Post your XML code for content_welcome, the NPE indicates the button is not in your layout, or is called something else. – Francesc Mar 17 '16 at 17:28
*but its already there in the code* @nandandasari - No, it isn't. The only button is `android:id="@+id/fab". Nothing in your XML has an id of `ibsignin`. – BSMP Mar 17 '16 at 18:26
I have defined the button code in xml file still im getting NPE @BSMP – nandan dasari Mar 18 '16 at 05:22

navigate to another page using the button: Unable to start activity ComponentInfo java.lang.NullPointerException

1 Answers1