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();
            }
        });
    }
}