Null Pointer Exception

Question

I am creating a mobile app on Eclipse Juno, there are no errors in the code of the different classes and it will run on the emulator. However when The first screen loads on the emulator and I select either of the buttons the app stops running and I get an error in the log cat about a NullPointerException but can't seem to find where this problem is. Does anyone have any ideas what I am doing wrong or what is causing the app to stop?

The purpose of the buttons on the first screen is to take the user to different areas of the app so without getting to select an area to go I can't do much with the app.

This is the code for my first screen: package com.example.independentretailers; import com.example.independentretailers.R; import android.support.v7.app.ActionBarActivity; import android.app.Activity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.content.*;

public class welcome extends Activity {


public void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.welcome);
addListenerOnButton();
addListenerOnButton1();
}

//to continue from welcome screen to customer login screen 
//when customer button is clicked 
public void addListenerOnButton() { 
Button CustomerButton = (Button) findViewById(R.id.button1);

CustomerButton.setOnClickListener(new OnClickListener(){

        @Override
        public void onClick(View v){
        Intent intent = new Intent   (getApplicationContext(),customerlogin.class);       
            startActivity(intent);

        }
    });
}

//to continue from welcome screen to retailer login screen 
//when retailer button is clicked 
public void addListenerOnButton1() { 
    Button RetailerButton = (Button) findViewById(R.id.button2);

    RetailerButton.setOnClickListener(new OnClickListener(){    

        @Override
        public void onClick(View v){
            Intent intent = new Intent (getApplicationContext(),retailerlogin.class);       
            startActivity(intent);

        }
    });

}
}

My Log Cat Error is:

03-30 18:56:19.716: E/ResourceType(536): Style contains key with bad entry: 0x01010479
03-30 18:56:19.806: I/dalvikvm(536): threadid=3: reacting to signal 3
03-30 18:56:19.876: I/dalvikvm(536): Wrote stack traces to '/data/anr/traces.txt'
03-30 18:56:19.996: D/gralloc_goldfish(536): Emulator without GPU emulation detected.
03-30 18:58:31.936: E/ResourceType(536): Style contains key with bad entry: 0x01010479
03-30 18:58:31.966: D/AndroidRuntime(536): Shutting down VM
03-30 18:58:31.966: W/dalvikvm(536): threadid=1: thread exiting with uncaught exception (group=0x409c01f8)
03-30 18:58:32.016: E/AndroidRuntime(536): FATAL EXCEPTION: main
03-30 18:58:32.016: E/AndroidRuntime(536): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.independentretailers/com.example.independentretailers.customerlogin}: java.lang.NullPointerException
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread.access$600(ActivityThread.java:123)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.os.Handler.dispatchMessage(Handler.java:99)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.os.Looper.loop(Looper.java:137)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread.main(ActivityThread.java:4424)
03-30 18:58:32.016: E/AndroidRuntime(536):  at java.lang.reflect.Method.invokeNative(Native Method)
03-30 18:58:32.016: E/AndroidRuntime(536):  at java.lang.reflect.Method.invoke(Method.java:511)
03-30 18:58:32.016: E/AndroidRuntime(536):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
03-30 18:58:32.016: E/AndroidRuntime(536):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
03-30 18:58:32.016: E/AndroidRuntime(536):  at dalvik.system.NativeStart.main(Native Method)
03-30 18:58:32.016: E/AndroidRuntime(536): Caused by: java.lang.NullPointerException
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.view.ViewGroup.addViewInner(ViewGroup.java:3336)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.view.ViewGroup.addView(ViewGroup.java:3208)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.view.ViewGroup.addView(ViewGroup.java:3188)
03-30 18:58:32.016: E/AndroidRuntime(536):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:270)
03-30 18:58:32.016: E/AndroidRuntime(536):  at com.android.internal.policy.impl.PhoneWindow.setContentView(PhoneWindow.java:260)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.Activity.setContentView(Activity.java:1855)
03-30 18:58:32.016: E/AndroidRuntime(536):  at com.example.independentretailers.customerlogin.onCreate(customerlogin.java:28)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.Activity.performCreate(Activity.java:4465)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
03-30 18:58:32.016: E/AndroidRuntime(536):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
03-30 18:58:32.016: E/AndroidRuntime(536):  ... 11 more
03-30 18:58:32.405: I/dalvikvm(536): threadid=3: reacting to signal 3
03-30 18:58:32.445: I/dalvikvm(536): Wrote stack traces to '/data/anr/traces.txt'
03-30 18:58:32.625: I/dalvikvm(536): threadid=3: reacting to signal 3
03-30 18:58:32.655: I/dalvikvm(536): Wrote stack traces to '/data/anr/traces.txt'

Any help at all would be greatly appreciated.

Your error shows "...11 more". Could you expand that please? — Prudhvi, Mar 30 '15 at 19:43
I'm new to this..how do I do that? the program itself has 0 errors? — Tmcc, Mar 30 '15 at 19:49
@prudhvi when I click on '11 more' it doesn't expand? the message just stays the same — Tmcc, Mar 30 '15 at 20:26
@prudhvi thank you for your help but sadly that didn't fix it the same issue is still occuring. — Tmcc, Mar 31 '15 at 09:53
@Tmcc I found out that you declared CustomerButton and RetailerButton at the top and then again you're doing that in addListenerOnButton() method. You have to remove either of them. See my updated answer below. — Prudhvi, Mar 31 '15 at 17:34
@prudhvi Thank you so much for your help! That worked for the Retailer Button but for some reason I am still getting the error when the CustomerButton is selected? — Tmcc, Mar 31 '15 at 18:11
@Tmcc did you add call this addListenerOnButton1(); in your code? — Prudhvi, Mar 31 '15 at 18:20
See my answer, I have clearly added both the button functions and also called them inside onCreate() method. — Prudhvi, Mar 31 '15 at 18:34
I have added this and it is still throwing the same error when Customer Button is selected. — Tmcc, Mar 31 '15 at 18:39
@prudhvi no still having the same issue but only with the Customer Button — Tmcc, Apr 01 '15 at 00:46
@prudhvi I have updated my code to my original message - thanks again for your help in this. — Tmcc, Apr 01 '15 at 09:54
@prudhvi just letting you know I have solved the problem - I added another import to the class and it worked. Thanks very much for all your help I really appreciate it. — Tmcc, Apr 01 '15 at 13:18

Prudhvi · Answer 1 · 2015-03-31T18:37:31.960

I think you don't have to nest one button click listener into another button's onClickListener. Also you declared buttons as instance variables and didn't initialize them, then you declared local buttons with same names inside your methods. Remove either of them to get them work. Try the below code.

public class welcome extends Activity {
    //Button CustomerButton; No need to declare these here.
    //Button RetailerButton;

    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome);
        addListenerOnButton();
        addListenerOnButton1();
    }

    //to continue from welcome screen to customer login screen 
    //when customer button is clicked 
    public void addListenerOnButton() { 
        Button CustomerButton = (Button) findViewById(R.id.button1);

        CustomerButton.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v){
                Intent intent = new Intent (getApplicationContext(),customerlogin.class);       
                startActivity(intent);

            }
        });
    }

    //to continue from welcome screen to retailer login screen 
    //when retailer button is clicked 
    public void addListenerOnButton1() { //This method was inside the first method earlier.
        Button RetailerButton = (Button) findViewById(R.id.button2);

        RetailerButton.setOnClickListener(new OnClickListener(){    

            @Override
            public void onClick(View v){
                Intent intent = new Intent (getApplicationContext(),retailerlogin.class);       
                startActivity(intent);

            }
        });

    }
}

Null Pointer Exception

1 Answers1