Handler 三秒執行一次

HandlerActivity.java

package com.jing.example.nknu_.handler;

import android.os.Bundle;

import android.os.Handler;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.Button;

public class HandlerActivity extends AppCompatActivity {

private Button startButton = null;

private Button endButton = null;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_handler);

startButton = (Button)findViewById(R.id.startButton);

startButton.setOnClickListener(new StartButtonListener());

endButton = (Button)findViewById(R.id.endButton);

endButton.setOnClickListener(new EndButtonListener());

}

private class StartButtonListener implements View.OnClickListener {

@Override

public void onClick(View v) {

//條用handler的post方法，將要執行的執行緒對象添加到隊列當豬

handler.post(updateThread);

}

}

private class EndButtonListener implements View.OnClickListener {

@Override

public void onClick(View v) {

handler.removeCallbacks(updateThread);

}

}

//創建一個handler對象

Handler handler = new Handler();

//將要執行的操作寫在執行緒對象的run方法當中

Runnable updateThread = new Runnable(){

@Override

public void run(){

System.out.println("UpdateThread");

//每三千毫秒將updateThread加入消息隊列

//在run方法內部，執行postDelayed或者是post方法

handler.postDelayed(updateThread, 3000);

}

};

}

content_handler.xml

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:app="http://schemas.android.com/apk/res-auto"

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"

app:layout_behavior="@string/appbar_scrolling_view_behavior"

tools:context="com.jing.example.nknu_.handler.HandlerActivity"

tools:showIn="@layout/activity_handler">

<Button

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="start"

android:id="@+id/startButton"

android:layout_centerVertical="true"

android:layout_alignParentStart="true" />

<Button

style="?android:attr/buttonStyleSmall"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="end"

android:id="@+id/endButton"

android:layout_alignBottom="@+id/startButton"

android:layout_alignParentEnd="true"

android:layout_marginEnd="55dp" />

</RelativeLayout>