Android定时器Timer的停止和重启实现代码

2019-12-12 02:21:37

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本文介绍了Android定时器Timer的停止和重启实现代码，分享给大家，具体如下：

7月份做了一个项目，利用自定义控件呈现一幅动画，当时使用定时器来控制时间，但是当停止开启时总是出现问题。一直在寻找合理的方法解决这个问题，一直没有找到，最近终于找到了合理的方法来解决这个问题。

大家如何查询有关资料，一定知道timer,timertask取消的方式是采用Timer.cancel()和mTimerTask.cancel()，可是大家发现这种发式取消后，再次开始timer时，会报错

 FATAL EXCEPTION: main         Process: com.example.zhongzhi.gate_control_scheme, PID: 2472         java.lang.IllegalStateException: Timer already cancelled.           at java.util.Timer.sched(Timer.java:397)           at java.util.Timer.schedule(Timer.java:248)           at com.example.zhongzhi.gate_control_scheme.MainActivity.onClick(MainActivity.java:401)           at android.view.View.performClick(View.java:5637)           at android.view.View$PerformClick.run(View.java:22429)           at android.os.Handler.handleCallback(Handler.java:751)           at android.os.Handler.dispatchMessage(Handler.java:95)           at android.os.Looper.loop(Looper.java:154)           at android.app.ActivityThread.main(ActivityThread.java:6119)           at java.lang.reflect.Method.invoke(Native Method)           at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)           at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

这个问题的解决采用cancle(),取消timer后，还需要清空timer。合理的代码应该是这样的：

mTimer.cancel();mTimer = null;mTimerTask.cancel();mTimerTask = null;

关键的问题解决完了，下面给出我的案例代码Mainactivity.Java：

public class MainActivity extends AppCompatActivity {  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.activity_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);    }  }}

xml部分代码：

<?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>

string部分代码：

<?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>

上面就是我的源代码，如果大家有什么问题可以留言进行探讨。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持武林网。

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