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Editor to share with you how to use Java threads, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to understand it!

The Java platform has been designed as a multithreaded environment from the beginning. While your main program is executing, other jobs such as fragment collection and event handling are performed in the background. In essence, you can think of these jobs as threads. They happen to be system-managed threads, but they are threads anyway. Threads enable you to define independent jobs without interfering with each other. The system will swap these jobs in and out of CPU so that (externally) they seem to be running at the same time.

You can also use multiple processes when you need to process multiple assignments in your program. These processes can be created by yourself, or you can manipulate system threads.

You need to use several different classes or interfaces for these multi-job processing:

Java.util.Timer class

Javax.swing.Timer class

Thread class

Runnable interface

For simple assignments, which usually need to be repeated, you can use the java.util.Timer class to tell it to "do it every half a second". Note: most system routines use milliseconds. Half a second is 500 milliseconds.

The task you want Timer to implement is defined in the java.util.TimerTask instance, where the running method contains the task to be performed. These are demonstrated in the Hi class, where the string "Hi" is displayed repeatedly on the screen until you press the Enter key.

Import java.util.*; public class Hi {public static void main (String args []) throws java.io.IOException {TimerTask task = new TimerTask () {public void run () {System.out.println ("Hi");}}; Timer timer = new Timer (); timer.schedule (task, 0500); System.out.println ("Press ENTER to stop"); System.in.read (new byte [10]) Timer.cancel ();}}

The way Java Runtime Environment works is that as long as there is a thread running, the program does not exit. In this way, when the cancel is called and no other thread is running, the program exits. There are some system threads running, such as the fragment collector. These system threads are also called background threads. The existence of background threads does not affect the closing of the running environment, only non-background threads ensure that the running environment is not closed.

The Javax.swing.Timer class works similarly to the java.util.timer class, but there are some differences to be aware of. * the running job is defined by the implementation of the ActionListener API. Second, the job is executed inside the event processing thread, unlike the java.util.Timer class outside it. This is important because it concerns how the Swing component set is designed.

If you are not familiar with Swing, it is a set of graphical components that can be used by Java programs. Swing is called single-threaded by the designer. This means that access to the internal contents of the Swing class must be done in a single thread. This particular thread is the event handling thread. So, for example, if you want to change the text of a Label component, you can't just call the setText method of Jlabel. Instead, you have to make sure that the setText call occurs in the event handling thread, which is where the javax.swing.Time class comes in handy.

To illustrate this second case, the following program displays the value of an increased counter. The value of the American half-second counter increases, and the new value is displayed.

Import javax.swing.*; import java.awt.*; import java.awt.event.*; public class Count {public static void main (String args []) {JFrame frame = new JFrame (); frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE); Container contentPane = frame.getContentPane (); final JLabel label = new JLabel ("", JLabel.CENTER); label.setFont (new Font ("Serif", Font.PLAIN, 36)); contentPane.add (label, BorderLayout.CENTER) ActionListener listener = new ActionListener () {int count = 0; public void actionPerformed (ActionEvent e) {count++; label.setText (Integer.toString (count));}}; Timer timer = new Timer (500,100); timer.start (); frame.setSize (300,100); frame.show ();}}

The results of the above procedures are:

In case you want to do more than a simple repetitive assignment, the java.lang.Thread class comes in handy. It allows you to control the basic functions yourself. By creating a subclass of Thread, you can detach your system and perform a long-running job, such as reading a file from the network, without hindering the running of your other programs. This long-running job will be defined in the run method. For more information, see the installation and configuration of the Java environment, the introduction to Solaris basics, the topic of the Java programming development manual, or enter the discussion group.

The second way is to create a subclass of the Thread class and implement the run method in the subclass, or implement the run method in the class that implements runnable, and pass this implementation to the constructor of Thread.

You might ask what's the difference. The Java programming language supports only a single inheritance. If you design a call to a class other than Thread, you can implement Runnable for your class, and it can be your job to be executed. Otherwise, you define a subclass of Thread to run your Run method without adding any other operations during the process.

For the third case of creating a Thread subclass, the following program generates a new thread to calculate the number of characters for a particular URL, which is passed in from the command line. During this process, the fourth scenario for implementing Runnable is demonstrated, printing out duplicate messages. Note that in the latter case of implementing Runnable, you must provide the code that repeats the message. You must sleep at the same time to allocate time and complete the operation. In both cases, compared to using Timer. The * * part of this program contains you reading commands from the command line to trigger the end of the program. Note that while the system reads the URL and prints the message, you can always press enter to end the program.

Import java.io.*; import java.net.*; public class Both {public static void main (String args []) {final String urlString = args [0]; final String message = args [1]; Thread thread1 = new Thread () {public void run () {try {URL url = new URL (urlString); URLConnection connection = url.openConnection (); InputStreamReader isr = new InputStreamReader (connection.getInputStream ()); BufferedReader reader = new BufferedReader (isr); int count = 0 While (reader.read ()! =-1) {count++;} System.out.println ("Size is:" + count); reader.close ();} catch (MalformedURLException e) {System.err.println ("Bad URL:" + urlString);} catch (IOException e) {System.err.println ("Bad URL O Problems");}; thread1.start () Runnable runnable = new Runnable () {public void run () {while (true) {System.out.println (message); try {Thread.sleep (500);} catch (InterruptedException e) {}; Thread thread2 = new Thread (runnable); thread2.start (); try {System.out.println ("Press ENTER to stop"); System.in.read (new byte [10]) } catch (IOException e) {System.out.println ("I System.exit O problems");} System.exit (0);}}

For there are multiple ways to handle threads, which technique you choose depends on you and the conditions you face. To be an effective Java programmer, although you usually don't have to learn all the contents and core libraries of the Java programming language, threads are an exception. The sooner you learn how threads work and how to use them, the sooner you will understand how Java programs work and interact.

These are all the contents of the article "how to use Java threads". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

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