Java 线程组
线程组是一个用于创建线程组的类。这组线程是树结构的形式，其中初始线程是父线程。一个线程可以拥有组中其他线程的所有信息，但是可以拥有其他组的线程的信息。这在我们想要暂停和恢复大量线程的情况下非常有用。这个线程组是由 java.lang.ThreadGroup 类实现的。
线程组中有两种类型的构造器，如下所示:
1.公共线程组(字符串名称)
2.公共线程组(线程组父级，字符串名称)
以下是线程组中的方法
1。checkAccess()
在 Java 中，checkAccess()方法属于 ThreadGroup 类。用于检查线程组中运行的线程是否有修改权限。
语法
public final void checkAccess()
示例:
class ThreadDemo1_1 extends Thread
{
ThreadDemo1_1(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (int i = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName());
}
}
public class ThreadDemo1
{
public static void main(String arg[]) throws InterruptedException, SecurityException
{
ThreadGroup obj1 = new ThreadGroup("Parent thread =====> ");
ThreadGroup obj2 = new ThreadGroup(obj1, "child thread =====> ");
ThreadDemo1_1 t1 = new ThreadDemo1_1("*******Thread-1*******", obj1);
t1.start();
ThreadDemo1_1 t2 = new ThreadDemo1_1("*******Thread-2*******", obj1);
t2.start();
obj1.checkAccess();
System.out.println(obj1.getName() + " has access");
obj2.checkAccess();
System.out.println(obj2.getName() + " has access");
}
}
2 .activeCount()
在 Java 中，activeCount()方法属于 ThreadGroup 类。它用于统计组中当前正在运行的活动线程。
public static int activeCount()
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
Syste m.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName());
}
}
public class ThreadDemo2
{
public static void main(String arg[])
{
ThreadGroup o1 = new ThreadGroup("parent thread group");
Demo2 obj1 = new Demo2 ("Thread 1 =====> ", o1);
Demo2 obj2 = new Demo2 ("Thread 2 =====> ", o1);
Demo2 obj3 = new Demo2 ("Thread 3 =====> ", o1);
Demo2 obj4 = new Demo2 ("Thread 4 =====> ", o1);
Demo2 obj5 = new Demo2 ("Thread 5 =====> ", o1);
Demo2 obj6 = new Demo2 ("Thread 6 =====> ", o1);
obj1.start();
obj2.start();
obj3.start();
obj4.start();
obj5.start();
obj6.start();
System.out.println("Total number of active thread =====> "+ o1.activeCount());
}
}
3 .activeGroupCount()
在 Java 中，activeGroupCount()方法属于 ThreadGroup 类。它用于计算当前正在运行的活动线程组。
语法公共 int activeGroupCount()。
public int activeGroupCount().
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName()+" =====> completed executing");
}
}
public class ThreadDemo2
{
public static void main(String arg[])
{
ThreadGroup o1 = new ThreadGroup("parent thread group");
ThreadGroup o2 = new ThreadGroup(o1,"Child thread group");
ThreadGroup o3 = new ThreadGroup(o1,"parent thread group");
Demo2 obj1 = new Demo2("*****Thread 1*****",o1);
System.out.println(obj1.getName() + " =====> starts");
obj1.start();
System.out.println("Total number of active thread =====> "+ o1.activeGroupCount());
}
}
4。销毁()
在 Java 中，destroy()方法是 ThreadGroup 的。它用来摧毁一个线程组。要销毁任何线程组，必须停止该组中的所有线程。
语法
public void destroy()
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName()+" =====> completed executing");
}
}
public class ThreadDemo2
{
public static void main(String arg[]) throws InterruptedException, SecurityException
{
ThreadGroup o1 = new ThreadGroup("*****parent thread group*****");
ThreadGroup o2 = new ThreadGroup(o1,"*****Child thread group*****");
Demo2 obj1 = new Demo2("*****Thread 1*****",o1);
obj1.start();
Demo2 obj2 = new Demo2("*****Thread 2*****",o1);
obj2.start();
obj1.join();
obj2.join();
o2.destroy();
System.out.println(o2.getName()+" ====> Destroyed");
o1.destroy();
System.out.println(o1.getName()+" ====> Destroyed");
}
}
5。枚举(线程[]列表)
在 Java 中，enumerate()方法属于 ThreadGroup 类。它用于将活动线程复制到指定的数组中。
public int enumerate(Thread[] array)
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName()+" =====> completed executing");
}
}
public class ThreadDemo2
{
public static void main(String arg[])
{
ThreadGroup o1 = new ThreadGroup("*****parent thread group*****");
ThreadGroup o2 = new ThreadGroup(o1,"*****Child thread group*****");
Demo2 obj1 = new Demo2("*****Thread 1*****",o1);
System.out.println("Thread 1 Starts");
obj1.start();
Demo2 obj2 = new Demo2("*****Thread 2*****",o1);
System.out.println("Thread 2 Starts");
obj2.start();
Thread[] tarray = new Thread[o1.activeCount()];
int count1 = o1.enumerate(tarray);
for (inti = 0; i< count1; i++)
System.out.println(tarray[i].getName() + " =====> Found");
}
}
6。get axpriority()
在 Java 中，getMaxPriority()方法属于 ThreadGroup 类。它用于检查线程组的最大优先级。
语法
public final int getMaxPriority()
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName());
}
}
System.out.println(Thread.currentThread().getName()+" =====> completed executing");
}
}
public class ThreadDemo2
{
public static void main(String arg[])
{
ThreadGroup o1 = new ThreadGroup("*****parent thread group*****");
System.out.println("Maximum priority of Parent Thread: " + o1.getMaxPriority());
ThreadGroup o2 = new ThreadGroup(o1,"*****Child thread group*****");
System.out.println("Maximum priority of Child Thread: " + o2.getMaxPriority());
Demo2 obj1 = new Demo2("*****Thread 1*****",o1);
System.out.println("Thread 1 Starts");
obj1.start();
Demo2 obj2 = new Demo2("*****Thread 2*****",o1);
System.out.println("Thread 2 Starts");
obj2.start();
}
}
7.getName（）
在 Java 中，getName()方法属于 ThreadGroup 类。它用于获取当前线程组的名称。
public final String getName()
示例:
class Demo3 extends Thread
{
Demo3(String a, ThreadGroup b)
{
super(b, a);
start();
}
public void run()
{
System.out.println(Thread.currentThread().getName());
}
}
public class ThreadDemo3
{
public static void main(String arg[]) throws InterruptedException,
SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup(o1, "*****Child thread*****");
Demo3 obj1 = new Demo3("Thread-1", o1);
System.out.println("Name of First threadGroup : " +obj1.getThreadGroup().getName());
Demo3 obj2 = new Demo3("Thread-2", o2);
System.out.println("Name of Second threadGroup: " +obj2.getThreadGroup().getName());
}
}
8 .get arent()
在 Java 中，getParent()方法属于 ThreadGroup 类。它用于从线程组中获取父线程。
public final ThreadGroup getParent()
示例:
class Demo3 extends Thread
{
Demo3(String a, ThreadGroup b)
{
super(b, a);
start();
}
public void run()
{
System.out.println(Thread.currentThread().getName());
}
}
public class ThreadDemo3
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup(o1, "*****Child thread*****");
Demo3 obj1 = new Demo3("Thread-1", o1);
System.out.println("Thread one starting");
obj1.start();
Demo3 obj2 = new Demo3("Thread-2", o2);
System.out.println("Thread second starting");
obj2.start();
System.out.println("Parent Thread Group for " + o1.getName() + " is " + o1.getParent().getName());
System.out.println("Parent Thread Group for " + o2.getName() + " is " + o2.getParent().getName());
}
}
9。中断()
在 Java 中，interrupt()方法属于 ThreadGroup 类。它用于中断线程组的所有线程。
语法
public final void interrupt()
示例:
class Demo2 extends Thread
{
Demo2 (String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (inti = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex)
{
System.out.println(Thread.currentThread().getName()+ " =====> interrupted");
}
}
System.out.println(Thread.currentThread().getName()+" =====> completed executing");
}
}
public class ThreadDemo2
{
public static void main(String arg[]) throws InterruptedException, SecurityException
{
ThreadGroup o1 = new ThreadGroup("*****parent thread group*****");
ThreadGroup o2 = new ThreadGroup(o1,"*****Child thread group*****");
Demo2 obj1 = new Demo2("*****Thread 1*****",o1);
System.out.println(obj1.getName()+"Thread 1 Starts");
obj1.start();
o1.interrupt();
Demo2 obj2 = new Demo2("*****Thread 2*****",o1);
System.out.println(obj2.getName()+"Thread 2 Starts");
obj2.start();
}
}
10。isDaemon()
在 Java 中，isDaemon()方法属于 ThreadGroup 类。它用于检查一个线程是否是 Daemon 线程。
语法
public final boolean isDaemon()
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(inti = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
Demo4 obj1 = new Demo4 ("*****Thread-1*****", o1);
obj1.start();
System.out.println("Is " + o1.getName() + " a daemon threadGroup? " + o1.isDaemon());
}
}
11。setDaemon(Boolean daemon)
在 Java 中，setDaemon()方法属于 ThreadGroup 类。它用于使一个线程成为守护线程。
语法:
public final void setDaemon(boolean daemon)
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
o1.setDaemon(true);
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
o2.setDaemon(true);
Demo4 obj1 = new Demo4 ("*****Thread-1*****", o1);
obj1.start();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
obj2.start();
System.out.println("Is " + o1.getName() + " a daemon threadGroup? " + o1.isDaemon());
System.out.println("Is " + o2.getName() + " a daemon threadGroup? " + o2.isDaemon());
}
}
12。isdstoryed()
在 Java 中，isDestroyed()方法属于 ThreadGroup 类。用于检查线程组是否被破坏。
语法
public boolean isDestroyed()
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
Demo4 obj1 = new Demo4 ("*****Thread-1*****", o1);
System.out.println("Starting Thread 1");
obj1.start();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
System.out.println("Starting Thread 2");
obj2.start();
if(o1.isDestroyed()==true)
System.out.println("The Group is destroyed");
else
System.out.println("The Group is not destroyed");
}
}
13。list()
在 Java 中，list()方法属于 ThreadGroup 类。它用于获取关于线程组的所有信息。它在调试时非常有用。
语法
public void list()
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
Demo4 obj1 = new Demo4("*****Thread-1*****", o1);
System.out.println(obj1.getName()+"Starting Thread 1");
obj1.start();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
System.out.println(obj2.getName()+"Starting Thread 2");
obj2.start();
System.out.println("List of parent Thread Group: " + o1.getName() + ":");
o1.list();
}
}
14。ParentOf(ThreadGroup g)
在 Java 中，ParentOf()方法属于 ThreadGroup 类。它用于检查当前运行的线程是否是哪个线程组的父线程。
语法
public final boolean parentOf(ThreadGroup g)
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
Demo4 obj1 = new Demo4("*****Thread-1*****", o1);
System.out.println(obj1.getName()+"Starting Thread 1");
obj1.start();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
System.out.println(obj2.getName()+"Starting Thread 2");
obj2.start();
boolean isParent = o2.parentOf(o1);
System.out.println(o2.getName() + " is the parent of " + o1.getName() +": "+ isParent);
isParent = o1.parentOf(o2);
System.out.println(o1.getName() + " is the parent of " + o2.getName() +": "+ isParent);
}
}
15。suspend()
在 Java 中，suspend()方法属于 ThreadGroup 类。它用于挂起线程组的所有线程。
语法
public final void suspend()
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
Demo4 obj1 = new Demo4("*****Thread-1*****", o1);
System.out.println(obj1.getName()+"Starting Thread 1");
obj1.start();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
System.out.println(obj2.getName()+"Starting Thread 2");
obj2.start();
o1.suspend();
}
}
16。简历()
在 Java 中，resume()方法属于 ThreadGroup 类。它用于恢复线程组中所有挂起的线程。
语法
public final void resume()
示例:
class Demo4 extends Thread
{
Demo4(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for(int i = 0;i < 10;i++)
{
i++;
}
System.out.println(Thread.currentThread().getName() + " ====> Execution Finished");
}
}
public class ThreadDemo4
{
public static void main(String arg[]) throws InterruptedException, SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent thread*****");
ThreadGroup o2 = new ThreadGroup("*****Child thread*****");
Demo4 obj1 = new Demo4("*****Thread-1*****", o1);
System.out.println(obj1.getName()+"Starting Thread 1");
obj1.start();
o1.suspend();
Demo4 obj2 = new Demo4 ("*****Thread-2*****", o2);
System.out.println(obj2.getName()+"Starting Thread 2");
obj2.start();
o1.resume();
}
}
17。setmaxpriority(inti)
在 Java 中，setMaxPriority()方法属于 ThreadGroup 类。它用于设置线程组的最大优先级。
语法
public final void setMaxPriority(int pri)
示例:
class Demo5 extends Thread
{
Demo5(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (int i = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex) {
System.out.println("Thread " + Thread.currentThread().getName() + " =====> Interrupted"); }
}
System.out.println(Thread.currentThread().getName() + " [Priority = " +
Thread.currentThread().getPriority() + "]");
System.out.println(Thread.currentThread().getName()+" =====> Execution finish");
}
}
public class ThreadDemo5
{
public static void main(String arg[]) throws InterruptedException,
SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent threadGroup*****");
ThreadGroup o2 = new ThreadGroup(o1, "*****Child threadGroup*****");
o1.setMaxPriority(Thread.MAX_PRIORITY-3);
o2.setMaxPriority(Thread.MIN_PRIORITY);
Demo5 obj1 = new Demo5("*****Thread-1*****", o1);
obj1.setPriority(Thread.MAX_PRIORITY);
System.out.println(obj1.getName() + " ====> starts");
obj1.start();
Demo5 obj2 = new Demo5("*****Thread-2*****", o2);
obj2.setPriority(Thread.MAX_PRIORITY);
System.out.println(obj2.getName() + " ====> starts");
obj2.start();
}
}
18。stop()
在 Java 中，stop()方法属于 ThreadGroup 类。它用于停止线程组的线程。
语法
public final void stop()
示例:
class Demo5 extends Thread
{
Demo5(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (int i = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex) {
System.out.println("Thread " + Thread.currentThread().getName() + " =====> Interrupted"); }
}
System.out.println(Thread.currentThread().getName() + " [Priority = " +
Thread.currentThread().getPriority() + "]");
System.out.println(Thread.currentThread().getName()+" =====> Execution finish");
}
}
public class ThreadDemo5
{
public static void main(String arg[]) throws InterruptedException,
SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent threadGroup*****");
ThreadGroup o2 = new ThreadGroup(o1, "*****Child threadGroup*****");
o1.setMaxPriority(Thread.MAX_PRIORITY-3);
o2.setMaxPriority(Thread.MIN_PRIORITY);
Demo5 obj1 = new Demo5("*****Thread-1*****", o1);
System.out.println("Thread one starting");
obj1.start();
Demo5 obj2 = new Demo5("*****Thread-2*****", o2);
System.out.println("Thread second starting");
obj2.start();
o1.stop();
}
}
19。toString()
在 Java 中，toString()方法属于 ThreadGroup 类。它用于获取线程组的字符串表示形式。
语法
public String toString()
示例:
class Demo5 extends Thread
{
Demo5(String a, ThreadGroup b)
{
super(b, a);
}
public void run()
{
for (int i = 0; i< 10; i++)
{
try
{
Thread.sleep(10);
}
catch (InterruptedException ex) {
System.out.println("Thread " + Thread.currentThread().getName() + " =====> Interrupted"); }
}
System.out.println(Thread.currentThread().getName() + " [Priority = " +
Thread.currentThread().getPriority() + "]");
System.out.println(Thread.currentThread().getName()+" =====> Execution finish");
}
}
public class ThreadDemo5
{
public static void main(String arg[]) throws InterruptedException,
SecurityException, Exception
{
ThreadGroup o1 = new ThreadGroup("*****Parent threadGroup*****");
ThreadGroup o2 = new ThreadGroup(o1, "*****Child threadGroup*****");
Demo5 obj1 = new Demo5("*****Thread-1*****", o1);
System.out.println(obj1.getName() + " ====> starts");
obj1.start();
Demo5 obj2 = new Demo5("*****Thread-2*****", o2);
System.out.println(obj2.getName() + " ====> starts");
obj2.start();
System.out.println("String equivalent: " + o1.toString());
System.out.println("String equivalent: " + o2.toString());
}
}
