首先佈局頁面使用一個TextView控制元件，為展示倒計時的效果，也可自己新增背景

在主Actvity中實現倒計時跳轉

package com.example.ewm;

import android.app.Activity;
import android.content.Intent;
import android.os.Handler;
import android.os.Message;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;

public class MainActivity extends Activity {

private TextView time;
//首先寫一個從幾秒開始倒計時的int值
private int times = 5;

Handler handler = new Handler(){
    @Override
    public void handleMessage(Message msg) {
        super.handleMessage(msg);
        switch (msg.what){
            case 0:
                if (times>0){//判斷，如果倒計時這個數還大於0就繼續減減
                    times--;
                    time.setText("" + times);
                    Message message = new Message();
                    message.what = 0;
                    handler.sendMessageDelayed(message, 1000);
                }else {//否則就跳轉到要跳轉到你的下一個頁面
                    startActivity(new Intent(MainActivity.this, TwoActivity.class));
                    finish();
                }
                break;
        }
    }
};
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    time = findViewById(R.id.time);
    handler.sendEmptyMessage(0);//最後執行緒傳送一個訊息
}
 

}