Null pointer exception view holder in custom list view

Question

package com.example.ahmadal_bargouthy.project1;

import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.v4.content.ContextCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;

import static android.app.PendingIntent.getActivity;

public class MainActivity extends AppCompatActivity {


int[] IMAGES = {R.drawable.img1,R.drawable.img2,R.drawable.img3,R.drawable.img4,R.drawable.img5 ,R.drawable.img6,R.drawable.img7,R.drawable.img8,R.drawable.img9,R.drawable.img10};

    String[] NAMES = {"Lighter Watch","MINI TRACKER ANTI-LOST","FUNNY LION WIG","ROCKET LAUNCHER",
    "NEW SMART WATCH","LINE REWIND","LUMINOUS TEMPERED GLASS ","E58 DRONE WIFI","LED POWER MASK","PAINT SKULL 3D PRINTED HOODIES"};

    String[] DESC = {"Flameless windproof","SMART BLUETOOTH 4.0 TRACER GPS LOCATOR","FUNNY LION WIG HEAD CAP HAT WITH EAR",
            "ROCKET LAUNCHER DEFAULT GIRL SKIN DEFAULT SKIN FORTNITE","MEN WOMEN HEART RATE MONITOR BLOOD PRESSURE FITNESS TRACKER",
    "LINE REWIND 24K GOLD SERUM","CASE FOR IPHONE","FPV ANGLE HD CAMERA HIGH HOLD MODE"," "," "};

    String[] PRICE = {"20","15","12.95","25.98","27.98","23.99","14.95","24.95","38.18"};

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

        ListView listView = (ListView)findViewById(R.id.productList);

        CustomAdapter customAdapter = new CustomAdapter(this,NAMES,DESC,PRICE,IMAGES);

        listView.setAdapter(customAdapter);

        Intent i = getIntent();
        String userName = i.getStringExtra("User_Name");
        Toast toast = Toast.makeText(this,"Hello " + userName,Toast.LENGTH_LONG);
        toast.show();
        setTitle("Welcome " + userName);
    }

    class CustomAdapter extends ArrayAdapter<String>{

        private String[] NAMES;
        private String[] DESC;
        private String[] PRICE;
        private int[] IMAGES;

        private Activity context;

        public CustomAdapter(Activity context, String[]NAMES, String[] DESC , String[] PRICE, int[] IMAGES) {
            super(context, R.layout.customlayout,NAMES);

            this.context = context;

            this.NAMES = NAMES;
            this.DESC  = DESC;
            this.PRICE = PRICE;
            this.IMAGES = IMAGES;
        }

        @androidx.annotation.NonNull
        @Override
        public View getView(int position, @androidx.annotation.Nullable View convertView, @androidx.annotation.NonNull ViewGroup parent) {
                View r=convertView;

                ViewHolder viewHolder = null;

                if (r==null){
                    LayoutInflater layoutInflater = context.getLayoutInflater();
                    r=layoutInflater.inflate(R.layout.customlayout,null,true);
                    r.setTag(viewHolder);
                }else{
                    viewHolder = (ViewHolder)r.getTag();

            }

                ViewHolder vm = new ViewHolder();

                //vm.imageView.setImageResource(IMAGES[position]);

            int x = R.drawable.ic_launcher_background;

                viewHolder.imageView.setImageResource(x);
                viewHolder.nameTxt.setText(NAMES[position]);
                viewHolder.descTxt.setText(DESC[position]);
                viewHolder.priceTxt.setText(PRICE[position]);



            return r;
        }

        class ViewHolder{
            TextView nameTxt = (TextView)findViewById(R.id.Name);
            TextView descTxt = (TextView)findViewById(R.id.Desc);
            TextView priceTxt = (TextView)findViewById(R.id.Price);

            ImageView imageView =(ImageView)findViewById(R.id.imageView2);
        }
    }
}

here is my code i want to create a custom list view using ArrayAdapter and ViewHolder

i created customAdapter class and in GetView method im trying to get the data from the arrays (IMAGES,NAMES,DESC,PRICE)

when i run the code java.lang.NullPointerException error appears

  java.lang.NullPointerException: Attempt to read from field 'android.widget.ImageView com.example.ahmadal_bargouthy.project1.MainActivity$CustomAdapter$ViewHolder.imageView' on a null object reference
        at com.example.ahmadal_bargouthy.project1.MainActivity$CustomAdapter.getView(MainActivity.java:98)
        at android.widget.AbsListView.obtainView(AbsListView.java:2366)
        at android.widget.ListView.makeAndAddView(ListView.java:2052)
        at android.widget.ListView.fillDown(ListView.java:786)
        at android.widget.ListView.fillFromTop(ListView.java:847)
        at android.widget.ListView.layoutChildren(ListView.java:1826)
        at android.widget.AbsListView.onLayout(AbsListView.java:2165)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.support.constraint.ConstraintLayout.onLayout(ConstraintLayout.java:1915)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.support.v7.widget.ActionBarOverlayLayout.onLayout(ActionBarOverlayLayout.java:444)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1812)
        at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1656)
        at android.widget.LinearLayout.onLayout(LinearLayout.java:1565)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.widget.FrameLayout.layoutChildren(FrameLayout.java:323)
        at android.widget.FrameLayout.onLayout(FrameLayout.java:261)
        at com.android.internal.policy.DecorView.onLayout(DecorView.java:753)
        at android.view.View.layout(View.java:20672)
        at android.view.ViewGroup.layout(ViewGroup.java:6194)
        at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2792)
        at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2319)
        at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1460)
        at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:7183)
        at android.view.Choreographer$CallbackRecord.run(Choreographer.java:949)
        at android.view.Choreographer.doCallbacks(Choreographer.java:761)
        at android.view.Choreographer.doFrame(Choreographer.java:696)
        at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:935)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)

Help me please

You forgot to initialize your `viewHolder` before you call `r.setTag(viewHolder);`. — Aaron, Nov 20 '18 at 09:13
`viewHolder = new ViewHolder(...)` you never initialize your viewHolder — Vladyslav Matviienko, Nov 20 '18 at 09:21

score 1 · Answer 1 · edited Nov 20 '18 at 10:04

if (r==null){
    LayoutInflater layoutInflater = context.getLayoutInflater();

    r=layoutInflater.inflate(R.layout.customlayout,null,true);

            viewHolder.nameTxt = r.findViewById(R.id.Name);
            viewHolder.descTxt = r.findViewById(R.id.Desc);
            viewHolder.priceTxt = r.findViewById(R.id.Price);
            vewHolder.imageView = r.findViewById(R.id.imageView2);

                    r.setTag(viewHolder);
                }else{
                    viewHolder = (ViewHolder)r.getTag();
                }


       class ViewHolder{
            TextView nameTxt;
            TextView descTxt;
            TextView priceTxt;
            ImageView imageView;
        }

score 0 · Answer 2 · answered Nov 20 '18 at 09:23

0

If you need your class's fields to be initialized, you should use "static" modifier, this might solve the problem

answered Nov 20 '18 at 09:23

Dima Rich

61
6

Null pointer exception view holder in custom list view

2 Answers2