问在Android Studio的一个类中声明多个变量

EN

package ca.bcit.comp2052.a00587366.multiplewidgetsapp;

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.RatingBar;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

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

        // Start of rating bar

        RatingBar ratingBar1 = (RatingBar) findViewById(R.id.ratingBar1);
        ratingBar1.setOnRatingBarChangeListener(new RatingBar.OnRatingBarChangeListener() {
            @Override
            public void onRatingChanged(RatingBar ratingBar1, float rating, boolean fromUser) {
                // Implement your logic here               

                float total = 0;
                total += ratingBar1.getRating();
//                total += ratingBar2.getRating();
//                total += ratingBar3.getRating();
//                total += ratingBar4.getRating();
                float average = total / 4;
                setTitle("Average: " + average);

            }
        });
        // end of rating bar
        Button buttonNext = (Button) findViewById(R.id.nextButton);
        buttonNext.setOnClickListener(new 
        android.view.View.OnClickListener() {
            public void onClick(View v) {
                startActivity(new Intent(MainActivity.this, 
        Main2Activity.class));
            }
        });
    }
}