Android退出程序二次确认

偏执的太偏执、 2022-06-14 10:24 290阅读 0赞

1.使用onKeyUp(),点击第一次返回键会有吐司框提示，倘若在两秒内再次点击返回键，则退出程序，效果图如下：

![Center][]

代码如下：

package com.example.kongjian_11;
    
    import android.support.v7.app.AppCompatActivity;
    import android.os.Bundle;
    import android.view.KeyEvent;
    import android.widget.Toast;
    
    public class MainActivity extends AppCompatActivity {
    
        private long firstTime=0;
    
        @Override
        public boolean onKeyUp(int keyCode, KeyEvent event) {
            switch(keyCode){
                case KeyEvent.KEYCODE_BACK://点击返回键
                    long secondTime = System.currentTimeMillis();//以毫秒为单位
                    if(secondTime -firstTime>2000){
                        Toast.makeText(this, "再按一次返回退出程序", Toast.LENGTH_SHORT).show();
                        firstTime=secondTime;
                    }else{
                        finish();
                        System.exit(0);
                    }
                    return true;
            }
            return super.onKeyUp(keyCode, event);
        }
    
    
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
        }
    }

2.使用 onKeyDown()弹出提示框进行二次确认，效果图如下：

![Center 1][]

代码如下：

package com.example.kongjian_11;
    
    import android.content.DialogInterface;
    import android.os.Bundle;
    import android.support.annotation.Nullable;
    import android.support.v7.app.AlertDialog;
    import android.support.v7.app.AppCompatActivity;
    import android.view.KeyEvent;
    
    /**
     * Created by Administrator on 2017/6/17.
     */
    
    public class ItemActivity extends AppCompatActivity {
        @Override
        protected void onCreate(@Nullable Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_item);
        }
    
        @Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            if(keyCode==KeyEvent.KEYCODE_BACK){//如果点击了返回键
                //声明并初始化弹出对象
                AlertDialog.Builder builder=new AlertDialog.Builder(this);
                builder.setTitle("提示：");
                builder.setMessage("是否退出");
                //设置确认按钮
                builder.setNegativeButton("确定", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        finish();//退出程序
                    }
                });
                //设置取消按钮
                builder.setPositiveButton("取消",null);
                //显示弹框
                builder.show();
            }
            return super.onKeyDown(keyCode, event);
        }
    }

[Center]: /images/20220614/f74e9d5b4a80448b814d0502c441e482.png
[Center 1]: /images/20220614/28e8a5f791ad468583d6aebeedb298d5.png