ALMACENACION Y RECUPERACION SHAREDPREFERENCES EJERCICIO 2

package com.example.portafolioej3;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Context;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    TextView tvresul;
    Button btnrestar,btnsumar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvresul=(TextView) findViewById(R.id.tvresul);
        btnrestar=(Button) findViewById(R.id.btnrestar);
        btnsumar=(Button) findViewById(R.id.btnsumar);

        SharedPreferences preferences=getSharedPreferences("numeros", Context.MODE_PRIVATE);
        String v=String.valueOf(preferences.getInt("acumu",0));
        tvresul.setText(v);

    }
   public void onclick(View view){
       switch (view.getId()){
           case R.id.btnsumar:
               sumar();
               break;
           case R.id.btnrestar:
               restar();
               break;
           case R.id.btnsalir:
               salir();
               break;
       }

   }
   private void restar() {
        int res=Integer.parseInt(tvresul.getText().toString());
        res--;
        tvresul.setText(String.valueOf(res));
       SharedPreferences preferences=getSharedPreferences("numeros", Context.MODE_PRIVATE);
       SharedPreferences.Editor editor=preferences.edit();
       editor.putInt("acumu",res);
       editor.commit();

   }
   private void sumar(){
       int sum=Integer.parseInt(tvresul.getText().toString());
       sum++;
       tvresul.setText(String.valueOf(sum));
       SharedPreferences preferences=getSharedPreferences("numeros", Context.MODE_PRIVATE);
       SharedPreferences.Editor editor=preferences.edit();
       editor.putInt("acumu",sum);
       editor.commit();
   }
   private void salir(){
     finish();
   }
}