App crashes after button click implementation in fragments

Question

My app contains navigation drawer. And within that there is one item fragment. In that fragment I tried to implement three button click events to open 3 activities. But, whenever I click on the fragment from the navigation drawer the app crashes with nullPointerAcception. After debug it shows issues with the below code containing onClickListener:

itemButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent itemIntent=new Intent(getActivity(),ItemsActivity.class);
                startActivity(itemIntent);
            }
        });

Here's my fragment code.

import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;


/**
 * A simple {@link Fragment} subclass.
 */
public class ItemsFragment extends Fragment {

    Button itemButton;
    Button categoryButton;
    Button discountButton;

    public ItemsFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {


        itemButton=(Button) container.findViewById(R.id.items_button);
        categoryButton=(Button) container.findViewById(R.id.category_button);
        discountButton=(Button) container.findViewById(R.id.discount_button);

        itemButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent itemIntent=new Intent(getActivity(),ItemsActivity.class);
                startActivity(itemIntent);
            }
        });

        setHasOptionsMenu(false);
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_items, container, false);
    }

}

// The Logcat error

E/AndroidRuntime: FATAL EXCEPTION: main
                  java.lang.NullPointerException
                      at com.soumya.possystem.ItemsFragment.onCreateView(ItemsFragment.java:36)
                      at android.support.v4.app.Fragment.performCreateView(Fragment.java:2080)
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1108)
                      at android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1290)
                      at android.support.v4.app.BackStackRecord.run(BackStackRecord.java:801)
                      at android.support.v4.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1677)
                      at android.support.v4.app.FragmentManagerImpl$1.run(FragmentManager.java:536)
                      at android.os.Handler.handleCallback(Handler.java:725)
                      at android.os.Handler.dispatchMessage(Handler.java:92)
                      at android.os.Looper.loop(Looper.java:137)
                      at android.app.ActivityThread.main(ActivityThread.java:5041)
                      at java.lang.reflect.Method.invokeNative(Native Method)
                      at java.lang.reflect.Method.invoke(Method.java:511)
                      at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
                      at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
                      at dalvik.system.NativeStart.main(Native Method)

Possible duplicate of [Unfortunately MyApp has stopped. How can I solve this?](http://stackoverflow.com/questions/23353173/unfortunately-myapp-has-stopped-how-can-i-solve-this) — Code-Apprentice, Jan 18 '17 at 13:23
@SoumyaRauth please check the answer . this will resolve your problem http://stackoverflow.com/a/41720571/1140237 — user1140237, Jan 18 '17 at 13:32
Also see http://stackoverflow.com/questions/23353173/unfortunately-myapp-has-stopped-how-can-i-solve-this for information about fixing NullPointerExceptions. — Code-Apprentice, Jan 18 '17 at 15:26
Step through the code in the debugger. You will probably find that `itemButton=(Button) container.findViewById(R.id.items_button);` returns `null`. In this case it means that there is no `Button` with the ID `items_button` in the layout. — David Wasser, Jan 18 '17 at 21:52

user1140237 · Accepted Answer · 2017-01-18T13:29:53.080

Before inflating view and created view you are trying to find instance of the controls.and return inflated view in onCreateView

Another way is to take the instance(findviewById) in onViewCreated or onActivityCreated

Second issue is you are trying to get control's object from container instead of that you need to should take from inflated view.

View v=inflater.inflate(R.layout.fragment_items, container, false);

Below i have kept code with changes.

import android.content.Intent;
    import android.os.Bundle;
    import android.support.v4.app.Fragment;
    import android.view.LayoutInflater;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.Button;


    /**
     * A simple {@link Fragment} subclass.
     */
    public class ItemsFragment extends Fragment {

        Button itemButton;
        Button categoryButton;
        Button discountButton;

        public ItemsFragment() {
            // Required empty public constructor
        }


        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
    View v=inflater.inflate(R.layout.fragment_items, container, false);
    //check in place of container here you need to use inflated view (`v`) instance
            itemButton=(Button) v.findViewById(R.id.items_button);
            categoryButton=(Button) v.findViewById(R.id.category_button);
            discountButton=(Button) v.findViewById(R.id.discount_button);

            itemButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent itemIntent=new Intent(getActivity(),ItemsActivity.class);
                    startActivity(itemIntent);
                }
            });

            setHasOptionsMenu(false);
            // Inflate the layout for this fragment
            return v;
        }

    }

@jiteshmohite please check the code and comment i've kept where exactly NullPointerException giving crash — user1140237, Jan 18 '17 at 13:25

score 1 · Answer 2 · answered Jan 18 '17 at 13:30

1

You have to initialize view as per requirement:
Create a Fragment Class

So you have to do
View view = inflater.inflate(R.layout.YOUR_LAYOUT, container, false);
and then
itemButton=(Button) view.findViewById(R.id.items_button);

answered Jan 18 '17 at 13:30

Bhavana Vadodariya

2,287
1
19
26

Mohammed Junaid · Answer 3 · 2017-01-18T13:36:22.910

    public class ItemsFragment extends Fragment {

    Button itemButton;
    Button categoryButton;
    Button discountButton;

    public ItemsFragment() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
    /** Inflate rootView of fragment **/
    View rootView = inflater.inflate(R.layout.fragment_items, container, false);

      //replace "container" with "rootView" **/
        itemButton=(Button) rootView.findViewById(R.id.items_button);
        categoryButton=(Button) rootView.findViewById(R.id.category_button);
        discountButton=(Button) rootView.findViewById(R.id.discount_button);

        itemButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent itemIntent=new Intent(getActivity(),ItemsActivity.class);
                startActivity(itemIntent);
            }
        });

        setHasOptionsMenu(false);
        // Inflate the layout for this fragment
        return rootView; // Return the view object you inflated
    }

}

i'll suggest you to keep explanation for the issue. so user can understand the issue — user1140237, Jan 18 '17 at 13:39

score 0 · Answer 4 · answered Jan 18 '17 at 13:30

Try this

    View rootView = inflater.inflate(R.layout.fragment_id, container, false);
    itemButton=(Button) container.findViewById(R.id.items_button);
    categoryButton=(Button) container.findViewById(R.id.category_button);
    discountButton=(Button) container.findViewById(R.id.discount_button);
.
.
.

    return rootView;

score 0 · Answer 5 · answered Jan 18 '17 at 13:31

Try this:

public class ItemsFragment extends Fragment {

Button itemButton;
Button categoryButton;
Button discountButton;

public ItemsFragment() {
    // Required empty public constructor
}


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View v=inflater.inflate(R.layout.fragment_items, container, false);
    setHasOptionsMenu(false);
    return v;
}

 @Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
    super.onViewCreated(view, savedInstanceState);
   itemButton=(Button) view.findViewById(R.id.items_button);
    categoryButton=(Button) view.findViewById(R.id.category_button);
    discountButton=(Button) view.findViewById(R.id.discount_button);

    itemButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent itemIntent=new Intent(getActivity(),ItemsActivity.class);
            startActivity(itemIntent);
        }
    });

}
}

App crashes after button click implementation in fragments

5 Answers5