Android中定時器Timer和TimerTask的啓動，停止，暫停，繼續等操作實例

下面是一個在Android中使用定時器Timer和TimerTask的啓動，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 VM
W/dalvikvm( 6672): threadid=1: thread exiting with uncaught exception (group=0x40018560)
E/AndroidRuntime( 6672): FATAL EXCEPTION: main
E/AndroidRuntime( 6672): java.lang.IllegalStateException: Timer was canceled
E/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/.TimerDemoActivity
W/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 70ms
D/dalvikvm(  562): GC_EXPLICIT freed 59K, 51% free 2935K/5959K, external 245K/512K, paused 84ms
I/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主線程中更新控件/組件。在其他線程中，更新控件/組件，會提示出錯，提示如下： 
（注：這種情況下，可以通過Hander發送消息的方式來更新控件/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;  //1s
    private static int period = 1000;  //1s
    private static final int UPDATE_TEXTVIEW = 0;

    @Override
    public 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(){
            @Override
            public 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() {
                @Override
                public 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