应用开始界面简单倒计时的dialog

activity_main.xml

下面图片显示的还要在activity_main.xml里面加个TextView

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#FF85C17E"
    tools:context="com.example.lesson7_2_id19_dialog.MainActivity">
</RelativeLayout>

dialog_start.xml

 <?xml version="1.0" encoding="utf-8"?>
 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     android:background="@mipmap/timg">

     <TextView
         android:id="@+id/tv_time"
         android:gravity="center"
         android:background="@drawable/oval"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="3s"
         android:layout_alignParentRight="true"
         android:layout_margin="20dp"/>

 </RelativeLayout>

drawable下oval.xml  自定义圆圈

 <?xml version="1.0" encoding="utf-8"?>
 <shape xmlns:android="http://schemas.android.com/apk/res/android"
     android:shape="oval">
     <padding
         android:bottom="5dp"
         android:left="5dp"
         android:right="5dp"
         android:top="5dp" />
     <stroke
         android:width="1dp"
         android:color="#7bf0f2" />
 </shape>

java代码：

 package com.example.lesson7_2_id19_dialog;

 import android.app.Dialog;
 import android.content.Context;
 import android.os.Bundle;
 import android.os.CountDownTimer;
 import android.support.annotation.NonNull;
 import android.widget.TextView;

 /**
  * Created by Administrator on 2017/3/8 0008.
  */

 public class StartDialog extends Dialog {
     // 继承dialog重写构造方法
     public StartDialog(@NonNull Context context) {
         super(context, R.style.DialogStyle);

     }

     TextView tv_time;

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.dialog_start);
         // 设置是否可以关闭当前控件
         setCancelable(false);
         // 找到tv_time控件
         tv_time = (TextView) findViewById(R.id.tv_time);
         new DownTimer().start();
     }

         // 继承CountDownTimer类
     class DownTimer extends CountDownTimer {

         public DownTimer() {
             // 设置时间4秒
             super(4000, 1000);
         }
         // 重写CountDownTimer的两个方法
         @Override
         public void onTick(long millisUntilFinished) {
             tv_time.setText(millisUntilFinished / 1000 + "s");
         }

         @Override
         public void onFinish() {
             StartDialog.this.dismiss();

         }

     }
 }

 package com.example.lesson7_2_id19_dialog;

 import android.content.DialogInterface;
 import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.widget.Toast;

 public class MainActivity extends AppCompatActivity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         StartDialog dialog = new StartDialog(this);
         dialog.show();
         dialog.setOnDismissListener(new DialogInterface.OnDismissListener() {
             @Override
             public void onDismiss(DialogInterface dialog) {
                 Toast.makeText(MainActivity.this, "应用开始页面关闭", Toast.LENGTH_SHORT).show();
             }
         });
     }
 }