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Three implementation methods of thread and the usage of handler

2022-07-26 05:24:00 【shuo277】

The first way ：

class MyThread extends Thread{
    public void run(){
        //  Write time-consuming operation code 
        // Only the original thread that created a view hierarchy can touch its views.
        //  If the child thread has performed a time-consuming operation , Then you can't modify the properties of the view ; View properties can only be in UI Thread to modify 
    }
}

MyThread myThead = new MyThread();
myThread.start();

The second way ：

class MyRunnable implements Runnable {
    @Override
    public void run() {
        try {
            Thread.sleep(3000);

            String result = "runnable 345345";
            Log.i("runnable", result);

        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

MyRunnable myRunnable = new MyRunnable();
Thread thread = new Thread(myRunnable);
thread.start();

The third way ：( common 、 recommend )

new Thread(new Runnable() {
    @Override
    public void run() {
        //  Time consuming tasks 
        try {
            Thread.sleep(3000);
            String result = " Anonymous threads ";
            Log.i(" Anonymous threads ",result);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}).start();

3、Handler

/**
* Received the user's nickname from the server , And set the nickname to textview Corresponding text Attribute
*
* The function of connecting to the server , It's a time-consuming task , So it must be placed in the sub thread
*
* There is no way to modify the page in the sub thread , With the help of Handler Pass messages to the main thread
*
* After the main thread receives the message , Start the modification UI

public class MainActivity2 extends AppCompatActivity {
// Declaring container
private TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
// according to ID Get page control
tv1 = findViewById(R.id.tv1);
// Simulate the process of connecting to the server
new Thread(new Runnable() {
@Override
public void run() {
try {
// The original intention is to express The time-consuming operation of connecting to the server
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
// If the nickname obtained from the server is ： Deep fried
String result = " Deep fried ";

// Give a nickname to textview Set up , Update... In child threads UI, It's not allowed , You have to use handler Pass the message back
Message message = new Message();
message.what = 1;
message.obj = result;
handler.sendMessage(message);
}
}).start();
}
private Handler handler = new Handler(Looper.getMainLooper()){
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
if (msg.what == 1) {
String result = (String) msg.obj;
tv1.setText(result);
}
}
};
}

4 Progress bar

public class MainActivity3 extends AppCompatActivity {
private ProgressBar progressBar;
int status = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main3);
progressBar = findViewById(R.id.progressBar);
new Thread(new Runnable() {
@Override
public void run() {
// Cycle pair status Make it worth modifying
while (status < 100) {
try {
Thread.sleep(100);
status++;
handler.sendEmptyMessage(0x111);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}).start();
}
private Handler handler = new Handler(Looper.getMainLooper()) {
@Override
public void handleMessage(@NonNull Message msg) {
super.handleMessage(msg);
if (msg.what == 0x111) {
progressBar.setProgress(status);
}
}
};
}

5.Service solve ANR

@Override
public int onStartCommand(Intent intent, int flags, int startId) {
   Log.i("serivce"," Service is turned on ");
   new Thread(new Runnable() {
@Override
public void run() {
long endtime = System.currentTimeMillis() + 20 * 1000; // Get the current system plus 20 second
while(System.currentTimeMillis() < endtime) {
synchronized (this){
try {
wait(endtime - System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
stopSelf();
       }
   }).start();
return super.onStartCommand(intent, flags, startId);
}

Conclusion ：

Service The thread will not start automatically , It will not automatically stop the thread

6 IntentService

How to create a IntentService

new Class-> MyIntentService -> Inherit IntentService-> Realization onHandleIntent and Construction method

stay AndroidManifest.xml Register in , An error is reported during registration , The reason for the error is that there is no parameter free construction method , terms of settlement ： Create parameterless construction methods