返回键弹出是否退出对话框

首先创建页面布局：

然后设置activity：

package com.example.administrator.myapplication;

import android.content.DialogInterface;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;

//控制手机自带按钮的一些属性的方法
public class DialogActivity extends AppCompatActivity {

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

    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
    //点击返回键
        if(keyCode==KeyEvent.KEYCODE_BACK){
            //声明弹出对象并初始化
            AlertDialog.Builder builder=new AlertDialog.Builder(this);
            builder.setTitle("提示：");
            builder.setMessage("是否退出?");
            //设置确定按钮
            builder.setNegativeButton("确定", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    finish();
                }
            });
            //设置取消按钮
            builder.setPositiveButton("取消",null);
            //显示弹窗
            builder.show();
        }
        return super.onKeyDown(keyCode,event);
    }
}