The Java Tutorials have been written for JDK 8.Java教程是为JDK 8编写的。Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.本页中描述的示例和实践没有利用后续版本中引入的改进，并且可能使用不再可用的技术。See Java Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.有关Java SE 9及其后续版本中更新的语言特性的摘要，请参阅Java语言更改。
See JDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.有关所有JDK版本的新功能、增强功能以及已删除或不推荐的选项的信息，请参阅JDK发行说明。
The HelloWorld applet shown next is a Java class that displays the string "Hello World".接下来显示的HelloWorld小程序是一个显示字符串“HelloWorld”的Java类。
Following is the source code for the HelloWorld applet:以下是HelloWorld小程序的源代码：
import javax.swing.JApplet;
import javax.swing.SwingUtilities;
import javax.swing.JLabel;
public class HelloWorld extends JApplet {
//Called when this applet is loaded into the browser.
public void init() {
//Execute a job on the event-dispatching thread; creating this applet's GUI.
try {
SwingUtilities.invokeAndWait(new Runnable() {
public void run() {
JLabel lbl = new JLabel("Hello World");
add(lbl);
}
});
} catch (Exception e) {
System.err.println("createGUI didn't complete successfully");
}
}
}An applet such as this is typically managed and run by the Java Plug-in software in the browser.这样的小程序通常由浏览器中的Java插件软件管理和运行。
Download source code for the Hello World example to experiment further.下载Hello World示例的源代码以进行进一步实验。