java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference

AndroidAndroid LayoutAndroid FragmentsAndroid Listview

Android Problem Overview

I'm trying to put together a shopping list app, based on input fields, ArrayList, and ListView. The app will be based on Fragments. However, I have encountered a problem and I do not know how to solve it.

I looked around on both Google and StackOverflow and I have found some information. However, I have not got it to work. Now I hope that I can get help with my code.

I'm relatively inexperienced in Android development.

Main.java

import java.util.ArrayList;

import android.app.Fragment;
import android.app.FragmentManager;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.view.Menu;
import android.view.MenuItem;

public class Main extends FragmentActivity {
	
	ArrayList<Detail> items = new ArrayList<Detail>();
	FragmentManager FM;
	FragmentTransaction FT;
	Input input = new Input();
	
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		
		replaceFragment(R.id.container, input);
	}

	
	public void replaceFragment(int container, Fragment fragment){
		FM = getFragmentManager();
		FT = FM.beginTransaction();
		
		FT.replace(container, fragment);
		FT.commit();
	}
	
	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

	@Override
	public boolean onOptionsItemSelected(MenuItem item) {
		// Handle action bar item clicks here. The action bar will
		// automatically handle clicks on the Home/Up button, so long
		// as you specify a parent activity in AndroidManifest.xml.
		int id = item.getItemId();
		if (id == R.id.action_settings) {
			return true;
		}
		return super.onOptionsItemSelected(item);
	}
}

ListAdapter.java

public class ListAdapter extends BaseAdapter {

	Context context;
	ArrayList<Detail> items;
	
	public ListAdapter(Context context, ArrayList<Detail> items) {
		this.context = context;
		this.items = items;
	}
	
	@Override
	public int getCount() {
		return items.size();
	}

	@Override
	public Object getItem(int position) {
		return items.get(position);
	}

	@Override
	public long getItemId(int position) {
		return items.indexOf(getItem(position));
	}

	@Override
	public View getView(int position, View convertView, ViewGroup parent) {
		
		if(convertView == null){
			LayoutInflater lInflater = (LayoutInflater)context.getSystemService(
					Activity.LAYOUT_INFLATER_SERVICE);
			
			convertView = lInflater.inflate(R.layout.list_row, null);		
		}
		
		TextView title = (TextView)convertView.findViewById(R.id.itemTitle);
		CheckBox done = (CheckBox)convertView.findViewById(R.id.itemDone);
		
		
		Detail detail_position = items.get(position);
		
		title.setText(detail_position.getTitle());
		done.setChecked(detail_position.isDone());
		
		return null;
	}
}

List.java

import java.util.ArrayList;

import android.app.ListFragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;

public class List extends ListFragment implements OnItemClickListener{

	ArrayList<Detail> items;
	ListAdapter adapter;
	private onClickListener OCL;

	interface onClickListener{
		public void onItemClick(int id);
	}

	public List(ArrayList<Detail> items) {
		this.items = items;
	}

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

		View root = inflater.inflate(R.layout.list_layout, container, false);
		return root;
	}

	@Override
	public void onActivityCreated(Bundle savedInstanceState) {
		super.onActivityCreated(savedInstanceState);

		if(items != null){
			adapter = new ListAdapter(getActivity(), items);
			setListAdapter(adapter);
			getListView().setOnItemClickListener(this);
		}

	}

	@Override
	public void onItemClick(AdapterView<?> parent, View view, int position,
			long id) {

		if(OCL != null){
			OCL.onItemClick(position);
		}		
	}
}

list_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/LinearLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <ListView
        android:id="@+id/android:list"
        android:layout_width="match_parent"
        android:layout_height="match_parent" >
    </ListView>
</LinearLayout>

list_row

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    android:padding="10dp" >
    <TextView
        android:id="@+id/itemTitle"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="0.96"
        android:text="Medium Text"
        android:textAppearance="?android:attr/textAppearanceMedium" />
    <CheckBox
        android:id="@+id/itemDone"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Done" />
</LinearLayout>

activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_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"
    tools:context="com.example.com.hermods.lab2_2.Main" >
</RelativeLayout>

Log

02-19 09:10:47.421: E/AndroidRuntime(12745): Process: com.example.com.hermods.lab2_2, PID: 12745
02-19 09:10:47.421: E/AndroidRuntime(12745): java.lang.NullPointerException: Attempt to invoke virtual method 'int android.view.View.getImportantForAccessibility()' on a null object reference
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.AbsListView.obtainView(AbsListView.java:2360)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.makeAndAddView(ListView.java:1864)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.fillDown(ListView.java:698)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.fillFromTop(ListView.java:759)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.ListView.layoutChildren(ListView.java:1673)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.AbsListView.onLayout(AbsListView.java:2148)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.RelativeLayout.onLayout(RelativeLayout.java:1076)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1703)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1557)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.LinearLayout.onLayout(LinearLayout.java:1466)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.layoutChildren(FrameLayout.java:573)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.widget.FrameLayout.onLayout(FrameLayout.java:508)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.View.layout(View.java:15596)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewGroup.layout(ViewGroup.java:4966)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2072)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1829)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer.doCallbacks(Choreographer.java:580)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer.doFrame(Choreographer.java:550)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Handler.handleCallback(Handler.java:739)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Handler.dispatchMessage(Handler.java:95)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.os.Looper.loop(Looper.java:135)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at android.app.ActivityThread.main(ActivityThread.java:5221)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at java.lang.reflect.Method.invoke(Native Method)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at java.lang.reflect.Method.invoke(Method.java:372)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
02-19 09:10:47.421: E/AndroidRuntime(12745): 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Android Solutions

Solution 1 - Android

In your public View getView method change return null; to return convertView;.

Solution 2 - Android

#use return convertView;

Code:

public View getView(final int position, View convertView, ViewGroup parent) {
   
	//convertView = null;

	if (convertView == null) {

		LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Activity.LAYOUT_INFLATER_SERVICE);
		convertView = mInflater.inflate(R.layout.list_item, null);     

		TextView tv = (TextView) convertView.findViewById(R.id.name);
		Button rm_btn = (Button) convertView.findViewById(R.id.rm_btn);

		Model m = modelList.get(position);
		tv.setText(m.getName());

		// click listener for remove button  คลิกลบปุ่ม
		rm_btn.setOnClickListener(new View.OnClickListener() {
			@Override
			public void onClick(View v) {
				modelList.remove(position);
				notifyDataSetChanged();
			}
		});
	}

	///#use    return convertView;
	return convertView;
}

Solution 3 - Android

in your baseadapter class constructor try to initialize LayoutInflater, normally i preferred this way,

public ClassBaseAdapter(Context context,ArrayList<Integer> listLoanAmount) {
    this.context = context;
    this.listLoanAmount = listLoanAmount;
    this.layoutInflater = LayoutInflater.from(context);
}

at the top of the class create LayoutInflater variable, hope this will help you

Solution 4 - Android

it sometimes occurs when we use a custom adapter in any activity of fragment . and we return null object i.e null view so the activity gets confused which view to load , so that is why this exception occurs

shows the position where to change the view

Solution 5 - Android

My silly mistake was this: change != to ==

if(convertView != null) { // <---- HERE 
                LayoutInflater layoutInflater = LayoutInflater.from(z_selBoardElectricity.this);
                convertView = layoutInflater.inflate(R.layout.listview_board_alert, null);

                TextView textView = convertView.findViewById(R.id.board_name_tv);
                ImageView imageView = convertView.findViewById(R.id.board_imageview);

                textView.setText(text_list.get(position));
                imageView.setImageDrawable(imageAddressList.get(position));

                convertView.setOnClickListener(new View.OnClickListener() {
                    @Override
                    public void onClick(View v) {
                        Intent intent = new Intent();
                        intent.putExtra("MESSAGE", text_list.get(pos));
                        setResult(98, intent);
                        finish();
                    }
                });
            }
return convertView;
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Attributions

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Content TypeOriginal AuthorOriginal Content on Stackoverflow
Questionuser2734182View Question on Stackoverflow
Solution 1 - AndroidPavyaView Answer on Stackoverflow
Solution 2 - AndroidPong PetrungView Answer on Stackoverflow
Solution 3 - AndroidAshana.JackolView Answer on Stackoverflow
Solution 4 - AndroidAakib JabbarView Answer on Stackoverflow
Solution 5 - AndroidVijayView Answer on Stackoverflow