App keeps crashing and giving a nullPointerException

Question

Every time I run my app it keeps crashing immediately and throwing a NullPointerException. I can't figure out where or why though.

LogCat:

10-13 02:23:05.028: E/AndroidRuntime(1610): FATAL EXCEPTION: main
10-13 02:23:05.028: E/AndroidRuntime(1610): Process: com.association.icecreammafiatesting3, PID: 1610
10-13 02:23:05.028: E/AndroidRuntime(1610): java.lang.RuntimeException: Unable to instantiate activity     ComponentInfo{com.association.icecreammafiatesting3/com.association.icecreammafiatesting3.MainActivity}: java.lang.NullPointerException
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.os.Handler.dispatchMessage(Handler.java:102)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.os.Looper.loop(Looper.java:136)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread.main(ActivityThread.java:5001)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at java.lang.reflect.Method.invokeNative(Native Method)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at java.lang.reflect.Method.invoke(Method.java:515)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at dalvik.system.NativeStart.main(Native Method)
10-13 02:23:05.028: E/AndroidRuntime(1610): Caused by: java.lang.NullPointerException
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.Activity.findViewById(Activity.java:1884)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at com.association.icecreammafiatesting3.MainActivity.<init>(MainActivity.java:19)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at java.lang.Class.newInstanceImpl(Native Method)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at java.lang.Class.newInstance(Class.java:1208)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
10-13 02:23:05.028: E/AndroidRuntime(1610):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
10-13 02:23:05.028: E/AndroidRuntime(1610):     ... 11 more

and here is the MainActivity:

public class MainActivity extends FragmentActivity {

private int totalMoney = 0;
private int moneyPerSec = 1;
private int moneyPerClick = 1;
Handler handleCounter = new Handler();

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);     

     TextView counter = (TextView)findViewById(R.id.tvMoney);
     TextView perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);
     Button buttonMoney = (Button)findViewById(R.id.buttonMoney);
     Button buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);

    ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
    pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

    handleCounter.post(updateCounter);

    buttonMoney.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            totalMoney += moneyPerClick;
            counter.setText(totalMoney);
        }
    });
    buttonMoneyPerSec.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            if (totalMoney >= 10){
                totalMoney -= 10;
                counter.setText(totalMoney);
                moneyPerSec++;
            }
        }
    });
}

Runnable updateCounter = new Runnable(){
    public void run(){
        totalMoney += moneyPerSec;
        counter.setText(totalMoney);
        handleCounter.postDelayed(this, 1000);
    }
};



private class MyPagerAdapter extends FragmentPagerAdapter {

    public MyPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int pos){
        switch(pos){
        case 0: return StandFragment.newInstance("STAND");
        case 1: return CartFragment.newInstance("CART");
        case 2: return ThirdFragment.newInstance("THIRD");
        case 3: return ThirdFragment.newInstance("FOURTH");
        case 4: return ThirdFragment.newInstance("FIFTH");
        default: return ThirdFragment.newInstance("Default");
        }
    }

    @Override
    public int getCount(){
        return 5;
    }
}
}

Changed where I was initializing, still throwing the same error. Here's the updated code:

public class MainActivity extends FragmentActivity {

private int totalMoney = 0;
private int moneyPerSec = 1;
private int moneyPerClick = 1;
TextView counter;
TextView perSecCounter;
Handler handleCounter = new Handler();
Button buttonMoney;
Button buttonMoneyPerSec;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    buttonMoney = (Button)findViewById(R.id.buttonMoney);
    buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);
    counter = (TextView)findViewById(R.id.tvMoney);
    perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);

    ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
    pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

    handleCounter.post(updateCounter);

    buttonMoney.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            totalMoney += moneyPerClick;
            counter.setText(totalMoney);
        }
    });
    buttonMoneyPerSec.setOnClickListener(new View.OnClickListener(){
        public void onClick(View v){
            if (totalMoney>=10){
                totalMoney-=10;
                counter.setText(totalMoney);
                moneyPerSec++;
            }
        }
    });
}

Updated LogCat:

10-13 12:21:46.236: E/AndroidRuntime(4323): FATAL EXCEPTION: main
10-13 12:21:46.236: E/AndroidRuntime(4323): Process: com.association.icecreammafiatesting3, PID: 4323
10-13 12:21:46.236: E/AndroidRuntime(4323): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.association.icecreammafiatesting3/com.association.icecreammafiatesting3.MainActivity}: java.lang.NullPointerException
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread.access$800(ActivityThread.java:135)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.os.Handler.dispatchMessage(Handler.java:102)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.os.Looper.loop(Looper.java:136)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread.main(ActivityThread.java:5001)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at java.lang.reflect.Method.invokeNative(Native Method)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at java.lang.reflect.Method.invoke(Method.java:515)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at dalvik.system.NativeStart.main(Native Method)
10-13 12:21:46.236: E/AndroidRuntime(4323): Caused by: java.lang.NullPointerException
10-13 12:21:46.236: E/AndroidRuntime(4323):     at com.association.icecreammafiatesting3.MainActivity.onCreate(MainActivity.java:40)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.Activity.performCreate(Activity.java:5231)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
10-13 12:21:46.236: E/AndroidRuntime(4323):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
10-13 12:21:46.236: E/AndroidRuntime(4323):     ... 11 more

As mentioned in one of the answers below, could this be due to trying to initialize in the main activity an object that is in a fragment? Because I'm using a pageViewer to have multiple screens. If so, I have no idea how I would move that code to that fragment. Because it won't allow me to initialize using findByID there.

That was the cause. After moving the code to the fragment, I added v. before the findViewById and it worked. Also, I remembered about an error I had previously. It won't let me assign a variable to text, I have to do .setText(""+variable).

you can not Initialize Button before creating view. So Initialize them in Oncreate method after setting your contentview. — Shvet, Oct 13 '14 at 06:36
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — Alexander_Winter, Oct 13 '14 at 06:43
Updated logcat? It must be showing error on another line. Not 19 anymore. — MysticMagicϡ, Oct 13 '14 at 08:31

M D · Answer 1 · 2014-10-13T06:40:52.217

You should move this

 Button buttonMoney = (Button)findViewById(R.id.buttonMoney);
 Button buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);
 TextView counter = (TextView)findViewById(R.id.tvMoney);
 TextView perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);

in your onCreate(...) after setContentView(R.layout.activity_main);

Corrected:

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);    

Button buttonMoney = (Button)findViewById(R.id.buttonMoney);
Button buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);
TextView counter = (TextView)findViewById(R.id.tvMoney);
TextView perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);

..........

Didn't I do that in lines 7&8? Or do I have to initialize them elsewhere? — Raistlin, Oct 13 '14 at 06:35

score 0 · Accepted Answer · answered Oct 13 '14 at 06:35

0

initialization of this controls should be inside oncreate method. So put this lines inside oncreate method after setContentView and error will be gone.

TextView counter = (TextView)findViewById(R.id.tvMoney);
TextView perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);
Button buttonMoney = (Button)findViewById(R.id.buttonMoney);
Button buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);

answered Oct 13 '14 at 06:35

Rajen Raiyarela

5,050
4
18
39

I changed where I was initializing, but it's still throwing the same error. – Raistlin Oct 13 '14 at 06:41
are you still getting NPE? Did you put initialization code above using all this controls and below setcontentview? – Rajen Raiyarela Oct 13 '14 at 06:42
share your activity_main.xml – Rajen Raiyarela Oct 13 '14 at 06:45
The activity_main is just a viewpager. The buttons and other elements are in another fragment. Would that be the issue? – Raistlin Oct 13 '14 at 06:48
yes that is the issue, as activity won't be able to initialize other controls and you are getting NPE. – Rajen Raiyarela Oct 13 '14 at 06:49
So should I instead move those initializations to my FirstFragment.java? – Raistlin Oct 13 '14 at 06:52
yes. Also the setonclicklisteners to be set inside fragment only. – Rajen Raiyarela Oct 13 '14 at 06:57
Alright. Also, if the FirstFragment is an extension of fragment, do I need to change it to fragmentActivity? – Raistlin Oct 13 '14 at 07:05
I added the code into the fragment. I had to add a 'v.' before the findViewById. It works now though! – Raistlin Oct 13 '14 at 16:55

score 0 · Answer 3 · answered Oct 13 '14 at 06:35

You are initializing your Buttons at wrong place initialize them inside onCreate() method before setting onClickListener and after setContentView()

As before setContentView your JAVA file is not connected or bind with any of the Layout file so you'll get NPE

TextView counter;
TextView perSecCounter;
Handler handleCounter = new Handler();
Button buttonMoney;
Button buttonMoneyPerSec;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);     
    // initialize them here
    // Like 
    counter = (TextView) findViewById(R.id.tvMoney);
    perSecCounter = (TextView) findViewById(R.id.tvMonPerSec);
    buttonMoney = (Button) findViewById(R.id.buttonMoney);
    buttonMoneyPerSec = (Button) findViewById(R.id.buttonMoneyPerSec);
}

I changed it to something like this, but it's still throwing the same error. Updating code now. — Raistlin, Oct 13 '14 at 06:41
It is definitely still an NPE, I'm not sure if it's EXACT same. But I'll upload what it says now. — Raistlin, Oct 13 '14 at 06:50

Mohd Mufiz · Answer 4 · 2014-10-13T06:45:32.987

0

You should initialize your widgets after setContentView(<layout_id>); As you have initialized as widgets as class members, it has not attached to any view and they are initialized as null.

You should initialize your Widgets before use

here you forget to initialize Buttons in onCrate(...); buttonMoney and buttonMoneyPerSec after setContentView(<layout_id>);

buttonMoney= (Button)findViewById(R.id.<your_btn_id>);

buttonMoneyPerSec= (Button)findViewById(R.id.<your_btn_id>);

then you set onClickListener on your buttons

cause of NPE

null.setOnClickListener(...);

edited Oct 13 '14 at 06:45

answered Oct 13 '14 at 06:39

Mohd Mufiz

2,176
15
28

OP had initialize Views but at different place. – SilentKiller Oct 13 '14 at 06:40
One can not initialize before setContentView(); and onCreate method called when activity created. – Mohd Mufiz Oct 13 '14 at 06:42
this line should be in your answer. :) – SilentKiller Oct 13 '14 at 06:43

score 0 · Answer 5 · answered Oct 13 '14 at 06:47

Your code should this way,

TextView counter,perSecCounter ;
Handler handleCounter;
Button buttonMoney,buttonMoneyPerSec ;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);     
counter = (TextView)findViewById(R.id.tvMoney);
perSecCounter = (TextView)findViewById(R.id.tvMonPerSec);
buttonMoney = (Button)findViewById(R.id.buttonMoney);
buttonMoneyPerSec = (Button)findViewById(R.id.buttonMoneyPerSec);
handleCounter = new Handler(); 
ViewPager pager = (ViewPager) findViewById(R.id.viewPager);
pager.setAdapter(new MyPagerAdapter(getSupportFragmentManager()));

handleCounter.post(updateCounter);

buttonMoney.setOnClickListener(new View.OnClickListener(){
    public void onClick(View v){
        totalMoney += moneyPerClick;
        counter.setText(totalMoney);
    }
});
buttonMoneyPerSec.setOnClickListener(new View.OnClickListener(){
    public void onClick(View v){
        if (totalMoney >= 10){
            totalMoney -= 10;
            counter.setText(totalMoney);
            moneyPerSec++;
        }
    }
});
}

App keeps crashing and giving a nullPointerException

5 Answers5

Corrected: