秒數倒數器

1.UI的xml檔

<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:paddingBottom="@dimen/activity_vertical_margin"

    android:paddingLeft="@dimen/activity_horizontal_margin"

    android:paddingRight="@dimen/activity_horizontal_margin"

    android:paddingTop="@dimen/activity_vertical_margin"

    tools:context=".MainActivity" >

    <TextView

        android:id="@+id/textView1"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:textStyle="bold"

        android:textSize="20sp"

        android:text="準備倒數" />

    <Button

        android:id="@+id/submit"

        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:layout_alignLeft="@+id/textView1"

        android:layout_below="@+id/textView1"

        android:layout_marginTop="33dp"

        android:text="Start" />

</RelativeLayout>

2.主程式程式碼

import android.os.Bundle;

import android.os.Handler;

import android.os.Message;

import android.app.Activity;

import android.view.Menu;

import android.view.View;

import android.view.View.OnClickListener;

import android.widget.Button;

import android.widget.TextView;

public class MainActivity extends Activity {

TextView tv;

Button button;

MyHandler han;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

tv = (TextView) this.findViewById(R.id.textView1);

button = (Button) this.findViewById(R.id.submit);

han = new MyHandler();

button.setOnClickListener(new OnClickListener() {

@Override

public void onClick(View arg0) {

new Thread(new Runnable() {

@Override

public void run() {

start();

}

}).start();

}

});

}

public void start() {

for (int i = 60; i >= 0; i--) {

try {

Message msg = new Message();

msg.arg1 = i;

han.sendMessage(msg);

Thread.sleep(1000);

} catch (InterruptedException e) {

}

}

}

class MyHandler extends Handler {

@Override

public void handleMessage(Message msg) {

int res = msg.arg1;

tv.setText("" + res);

}

}

}