threadgroup_Java ThreadGroup list（）方法与示例

threadgroup

ThreadGroup类的list()方法 (ThreadGroup Class list() method)

list() method is available in java.lang package.
list()方法在java.lang包中可用。
list() method is used to list or display information (like name, priority, thread group, etc.) to the standard output about this thread group.
list()方法用于将信息(例如名称，优先级，线程组等)列出或显示到有关此线程组的标准输出。
list() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.
list()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。
list() method does not throw an exception at the time of displaying information about this thread group.
在显示有关此线程组的信息时， list()方法不会引发异常。

Syntax:

句法：

    public void list();

Parameter(s):

参数：

It does not accept any parameter.
它不接受任何参数。

Return value:

返回值：

The return type of this method is void – it returns nothing.

此方法的返回类型为void –不返回任何内容。

Example:

例：

// Java program to demonstrate the example 
// of void list() method of ThreadGroup 
public class ListThreadGroup implements Runnable {
public static void main(String[] args) {
ListThreadGroup list_tg = new ListThreadGroup();
list_tg.listTG();
}
public void listTG() {
try {
// Create two thread group and the named are base
// and derived
ThreadGroup base = new ThreadGroup("Base ThreadGroup");
ThreadGroup derived = new ThreadGroup(base, "Derived ThreadGroup");
// create two threads
Thread th1 = new Thread(base, this);
Thread th2 = new Thread(derived, this);
// By using getName() method is to retrieve the
// name of the thread th1
System.out.println(th1.getName() + " " + "begins.....");
// By using start() method is to start its execution 
// of thread th1
th1.start();
// By using getName() method is to retrieve the
// name of the thread th2
System.out.println(th2.getName() + " " + "begins.....");
// By using start() method is to start its execution 
// of thread th2
th2.start();
System.out.println();
// By using list() method is to
// list the contents of the
// thread group to the std. output
System.out.println("base.list() :");
base.list();
System.out.println();
System.out.println("derived.list() :");
derived.list();
// By using join() method is to wait the current
// thread till complete execution of another
// thread
th1.join();
th2.join();
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
// Override run()
public void run() {
for (int k = 0; k < 100; ++k)
++k;
System.out.println(Thread.currentThread().getName() + " " + "ends.....");
}
}

Output

输出量

Thread-0 begins.....
Thread-0 ends.....
Thread-1 begins.....base.list() :
Thread-1 ends.....
java.lang.ThreadGroup[name=Base ThreadGroup,maxpri=10]java.lang.ThreadGroup[name=Derived ThreadGroup,maxpri=10]derived.list() :
java.lang.ThreadGroup[name=Derived ThreadGroup,maxpri=10]