Attempt to invoke virtual method on a null object reference in Android Studio

Question

I'm starting to learn Android Studio so please bypass my ignorance.

I'm getting this error code:

2020-05-12 19:32:35.398 13918-13918/com.fdev.Exploding_Tomatoes E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.fdev.Exploding_Tomatoes, PID: 13918
    java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
        at android.view.LayoutInflater.from(LayoutInflater.java:282)
        at com.fdev.Exploding_Tomatoes.Adapter.onCreateViewHolder(Adapter.java:25)
        at com.fdev.Exploding_Tomatoes.Adapter.onCreateViewHolder(Adapter.java:12)
        at androidx.recyclerview.widget.RecyclerView$Adapter.createViewHolder(RecyclerView.java:7078)
        at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6235)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6118)
        at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6114)
        at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2303)
        at androidx.recyclerview.widget.LinearLayoutManager.layout
2020-05-12 19:32:35.398 13918-13918/com.fdev.Exploding_Tomatoes E/AndroidRuntime:     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:957)
        at android.os.Handler.handleCallback(Handler.java:907)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:216)
        at android.app.ActivityThread.main(ActivityThread.java:7506)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:956)

This is my Adapter-script to get a (hopefully) working Recyclerview. The error is, or at least I think so, at "View view = LayoutInflater.from(context).inflate(R.layout.row, null);" I tried searching but couldn't find anything working. I substituted "null" with "this", removed it. But nothing.

package com.fdev.Exploding_Tomatoes;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

import java.util.ArrayList;

public class Adapter extends RecyclerView.Adapter<MyHolder> {
    private Context context;
    Context c;
    ArrayList<Model> models;

    public Adapter(Context c, ArrayList<Model> models) {
        this.c = c;
        this.models = models;
    }

    @NonNull
    @Override
    public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(context).inflate(R.layout.row, null);
        return new MyHolder(view);

    }

    @Override
    public void onBindViewHolder(@NonNull MyHolder myholder, int position) {
        myholder.mTitle.setText(models.get(1).getTitle());
        myholder.mNumber.setText(models.get(1).getNumber());
    }

    @Override
    public int getItemCount() {
        return models.size();
    }
}

Any help is appreciated!!! Thanks

However, now it is saying `java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference at android.view.LayoutInflater.from(LayoutInflater.java:282)` Thank you — Franky, May 12 '20 at 19:00
Basic NPE. You forgot to assign `private Context context;` in the constructor. It looks like you might've gotten it mixed up with `Context c;`, which you did assign. You only need one of those. — Mike M., May 13 '20 at 03:15
Does this answer your question? [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Mike M., May 13 '20 at 03:15

score 0 · Answer 1 · answered May 12 '20 at 17:50

instead of:

View view = LayoutInflater.from(context).inflate(R.layout.row, null);

replace it by :

View view = LayoutInflater.from(context).inflate(R.layout.row, parent, false);

the onCreateViewHolder method will be :

 @NonNull
        @Override
        public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(context).inflate(R.layout.row, parent, false);
    return new MyHolder(view);

        }

I'm happy of hearing that – Akram Bensalem May 12 '20 at 18:12 — Akram Bensalem, May 12 '20 at 18:12

score 0 · Answer 2 · answered May 12 '20 at 17:55

0

This:

@Override
public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(context).inflate(R.layout.row, null);
    return new MyHolder(view);

}

Must be like this:

@Override
public MyHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.row, parent, false);
    return new MyHolder(view);

}

answered May 12 '20 at 17:55

Hasan Bou Taam

4,017
2
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Great if that helped, accept the answer so that people facing same issues know what answer to look at. – Hasan Bou Taam May 12 '20 at 18:07

Attempt to invoke virtual method on a null object reference in Android Studio

2 Answers2