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androidviewmodelandroid-lifecycle

Problem initializing ViewModel instance using ViewModelProvider(this)


I am instantiating the ViewModel class instance but it is not taking the argument this. Please see my code. Its a simple code as I am trying to learn ViewModel and LiveData

I searched but everywhere ViewModelProviders explanation is given Please help to resolve

package com.nitin.viewmodellivedata;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.lifecycle.ViewModel;
import androidx.lifecycle.ViewModelProvider;
import androidx.lifecycle.ViewModelStoreOwner;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    TextView textView;
    Button buttonAdd;
    Button buttonReset;
    int score;
    ScoreViewModel scoreViewModel = new ViewModelProvider(ScoreViewModel);

    public void addScore(View view){
        scoreViewModel.addScore();
        textView.setText(String.valueOf(scoreViewModel.getScore()));
    }

    public void resetScore(View view){
        scoreViewModel.resetScore();
        textView.setText(String.valueOf(scoreViewModel.getScore()));
    }

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

        textView = (TextView)findViewById(R.id.textView);

        scoreViewModel = new ScoreViewModel();
        scoreViewModel = new ViewModelProvider(this).get(ScoreViewModel.class);

        textView.setText(String.valueOf(scoreViewModel.getScore()));
    }
}

Solution

  • Make sure you have both of dependencies in your build.gradle (:app) file:

    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'androidx.lifecycle:lifecycle-extensions:2.2.0'