Android中定時器Timer和TimerTask的啟動，停止，暫停，繼續等操作執行個體

下面是一個在Android中使用定時器Timer和TimerTask的啟動，停止，暫停，繼續等操作的demo。

需要注意的問題主要有兩點：

1、Timer和TimerTask在調用cancel()取消後不能再執行 schedule語句，否則提示出錯，提示如下：

D/AndroidRuntime( 6672): Shutting down VMW/dalvikvm( 6672): threadid=1: thread exiting with uncaught exception (group=0x40018560)E/AndroidRuntime( 6672): FATAL EXCEPTION: mainE/AndroidRuntime( 6672): java.lang.IllegalStateException: Timer was canceledE/AndroidRuntime( 6672): at java.util.Timer.scheduleImpl(Timer.java:563)E/AndroidRuntime( 6672): at java.util.Timer.schedule(Timer.java:483)E/AndroidRuntime( 6672): at com.snowdream.timerdemo.TimerDemoActivity$2.onClick(TimerDemoActivity.java:73)E/AndroidRuntime( 6672): at android.view.View.performClick(View.java:2501)E/AndroidRuntime( 6672): at android.view.View$PerformClick.run(View.java:9107)E/AndroidRuntime( 6672): at android.os.Handler.handleCallback(Handler.java:587)E/AndroidRuntime( 6672): at android.os.Handler.dispatchMessage(Handler.java:92)E/AndroidRuntime( 6672): at android.os.Looper.loop(Looper.java:130)E/AndroidRuntime( 6672): at android.app.ActivityThread.main(ActivityThread.java:3835)E/AndroidRuntime( 6672): at java.lang.reflect.Method.invokeNative(Native Method)E/AndroidRuntime( 6672): at java.lang.reflect.Method.invoke(Method.java:507)E/AndroidRuntime( 6672): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:841)E/AndroidRuntime( 6672): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:599)E/AndroidRuntime( 6672): at dalvik.system.NativeStart.main(Native Method)W/ActivityManager(  154):   Force finishing activity com.snowdream.timerdemo/.TimerDemoActivityW/ActivityManager(  154): Activity pause timeout for HistoryRecord{40550560 com.snowdream.timerdemo/.TimerDemoActivity}W/ActivityManager(  154): Activity destroy timeout for HistoryRecord{40550560 com.snowdream.timerdemo/.TimerDemoActivity}D/dalvikvm(  800): GC_EXPLICIT freed 13K, 58% free 3127K/7431K, external 0K/0K, paused 70msD/dalvikvm(  562): GC_EXPLICIT freed 59K, 51% free 2935K/5959K, external 245K/512K, paused 84msI/ActivityManager(  154): Start proc com.android.email for service com.android.email/.service.MailService: pid=6691 uid=10019 gids={3003, 1015}

2、只能在UI主線程中更新控制項/組件。在其他線程中，更新控制項/組件，會提示出錯，提示如下：

（註：這種情況下，可以通過Hander發送訊息的方式來更新控制項/組件，詳情參考例子。）

E/AndroidRuntime( 6309): android.view.ViewRoot$CalledFromWrongThreadException: Only the original thread that created a view hierarchy can touch its views.E/AndroidRuntime( 6309): at android.view.ViewRoot.checkThread(ViewRoot.java:2941)E/AndroidRuntime( 6309): at android.view.ViewRoot.invalidateChild(ViewRoot.java:643)E/AndroidRuntime( 6309): at android.view.ViewRoot.invalidateChildInParent(ViewRoot.java:669)E/AndroidRuntime( 6309): at android.view.ViewGroup.invalidateChild(ViewGroup.java:2511)E/AndroidRuntime( 6309): at android.view.View.invalidate(View.java:5296)E/AndroidRuntime( 6309): at android.widget.TextView.checkForRelayout(TextView.java:5533)E/AndroidRuntime( 6309): at android.widget.TextView.setText(TextView.java:2730)E/AndroidRuntime( 6309): at android.widget.TextView.setText(TextView.java:2598)E/AndroidRuntime( 6309): at android.widget.TextView.setText(TextView.java:2573)E/AndroidRuntime( 6309): at com.snowdream.timerdemo.TimerDemoActivity$1.run(TimerDemoActivity.java:48)E/AndroidRuntime( 6309): at java.util.Timer$TimerImpl.run(Timer.java:284)

Demo源碼如下：

TimerDemoActivity.java

package com.snowdream.timerdemo;import java.util.Timer;import java.util.TimerTask;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.util.Log;import android.view.View;import android.widget.Button;import android.widget.TextView;public class TimerDemoActivity extends Activity {private static String  TAG = "TimerDemo";private TextView mTextView = null;private Button mButton_start = null;private Button mButton_pause = null;private Timer mTimer = null;private TimerTask mTimerTask = null;private Handler mHandler = null;private static int count = 0;private boolean isPause = false;private boolean isStop = true;private static int delay = 1000;  //1sprivate static int period = 1000;  //1sprivate static final int UPDATE_TEXTVIEW = 0;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);mTextView = (TextView)findViewById(R.id.mytextview); mButton_start = (Button)findViewById(R.id.mybutton_start);mButton_pause = (Button)findViewById(R.id.mybutton_pause);mButton_start.setOnClickListener(new Button.OnClickListener() {public void onClick(View v) {if (isStop) {Log.i(TAG, "Start");} else {Log.i(TAG, "Stop");}isStop = !isStop;if (!isStop) {startTimer();}else {stopTimer();}if (isStop) {mButton_start.setText(R.string.start);} else {mButton_start.setText(R.string.stop);}}});mButton_pause.setOnClickListener(new Button.OnClickListener() {public void onClick(View v) {if (isPause) {Log.i(TAG, "Resume");} else {Log.i(TAG, "Pause");}isPause = !isPause;if (isPause) {mButton_pause.setText(R.string.resume);} else {mButton_pause.setText(R.string.pause);}}});mHandler = new Handler(){@Overridepublic void handleMessage(Message msg) {switch (msg.what) {case UPDATE_TEXTVIEW:updateTextView();break;default:break;}}};}private void updateTextView(){mTextView.setText(String.valueOf(count));}private void startTimer(){if (mTimer == null) {mTimer = new Timer();}if (mTimerTask == null) {mTimerTask = new TimerTask() {@Overridepublic void run() {Log.i(TAG, "count: "+String.valueOf(count));sendMessage(UPDATE_TEXTVIEW);do {try {Log.i(TAG, "sleep(1000)...");Thread.sleep(1000);} catch (InterruptedException e) {}} while (isPause);count ++;  }};}if(mTimer != null && mTimerTask != null )mTimer.schedule(mTimerTask, delay, period);}private void stopTimer(){if (mTimer != null) {mTimer.cancel();mTimer = null;}if (mTimerTask != null) {mTimerTask.cancel();mTimerTask = null;}count = 0;}public void sendMessage(int id){if (mHandler != null) {Message message = Message.obtain(mHandler, id);   mHandler.sendMessage(message); }}}

layout-main.xml

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent"    android:orientation="vertical" >    <TextView        android:id="@+id/mytextview"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:text="@string/number" />    <LinearLayout        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:gravity="center"        android:orientation="horizontal" >        <Button            android:id="@+id/mybutton_start"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/start" />        <Button            android:id="@+id/mybutton_pause"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="@string/pause" />    </LinearLayout></LinearLayout>

strings.xml

<?xml version="1.0" encoding="utf-8"?><resources>    <string name="app_name">TimerDemo</string>    <string name="number">0</string>    <string name="start">start</string>    <string name="stop">stop</string>    <string name="pause">pause</string>    <string name="resume">resume</string></resources>

源碼下載：

http://download.csdn.net/detail/yang_hui1986527/3922447