代码清单1-7 添加成员变量

package com.bignerdranch.android.quize;

import android.widget.Button;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class QuizActivity extends AppCompatActivity {
    private Button mTrueButton;
    private Button mFalseButton;

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