close
<?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"
tools:context=".MainActivity">
<Button android:id="@+id/btn_run"
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="Run"
android:textAllCaps="false"
/>
<Button android:id="@+id/btn_pause"
android:layout_below="@id/btn_run"
android:layout_width="match_parent"
android:layout_height="50dp"
android:text="Pause"
android:textAllCaps="false"
/>
<TextView
android:id="@+id/txt_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:textColor="@color/white"
android:background="@color/black"
android:text="counter"
android:gravity="center"
android:textSize="30dp"/>
</RelativeLayout>
Runnable(Observable): In the override method run(), it is continuously doing a while loop.
In the loop, there is a handler called mHandler. It is responsible to send message to its observers.
mCallback(Observer): It is also a worker, which will be notified by the mHandler.
mCallback has a handleMessage subroutine, which defines what should be done in the job.
Now we're going to create another thread to run a runnable, ie. mRunnable
public class MyCounter{
private boolean mRunning = false;
private boolean mPause = false;
private Thread mThread;
private long cnt = 0;
private Runnable mRunnable;
private Handler mHandler;
private Handler.Callback mCallback;
private final int mKey = 1;
public MyCounter()
{
mRunnable = new Runnable() {
@Override
public void run() {
do {
try {
Thread.sleep(1);
Message msg = new Message();
msg.what = mKey;
if(!mPause)
{
mHandler.sendMessage(msg);
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}while(mRunning);
}
};
mCallback = new Handler.Callback() {
@Override
public boolean handleMessage(@NonNull Message msg) {
switch (msg.what)
{
case mKey:
cnt++;
mTxt.setText("cnt:"+cnt);
break;
default:
break;
}
return false;
}
};
mHandler = new Handler(mCallback);
};
public void Run()
{
mThread = new Thread(mRunnable);
mRunning = true;
mThread = new Thread(mRunnable);
mRunning = true;
mThread.start();
mThread.start();
}
public void Pause()
{
mPause = true;
}
public void Resume()
{
mPause = false;
}
}
References:
1. Android：使用Handler與Thread更新UI
2. https://developer.android.com/reference/android/os/Handler
3. How to get the current time in YYYY-MM-DD HH:MI:Sec.Millisecond format in Java
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