void checkAccess()
描述 (Description)
java.lang.ThreadGroup.checkAccess()方法确定当前运行的线程是否具有修改此线程组的权限。
声明 (Declaration)
以下是java.lang.ThreadGroup.checkAccess()方法的声明
public final void checkAccess()
参数 (Parameters)
NA
返回值 (Return Value)
此方法不返回任何值。
异常 (Exception)
SecurityException - 如果不允许当前线程访问此线程组。
例子 (Example)
以下示例显示了java.lang.ThreadGroup.checkAccess()方法的用法。
package com.iowiki;
import java.lang.*;
public class ThreadGroupDemo implements Runnable {
public static void main(String[] args) {
ThreadGroupDemo tg = new ThreadGroupDemo();
tg.func();
}
public void func() {
try {
// create a parent ThreadGroup
ThreadGroup pGroup = new ThreadGroup("Parent ThreadGroup");
// create a child ThreadGroup for parent ThreadGroup
ThreadGroup cGroup = new ThreadGroup(pGroup, "Child ThreadGroup");
// create a thread
Thread t1 = new Thread(pGroup, this);
System.out.println("Starting " + t1.getName() + "...");
t1.start();
// create another thread
Thread t2 = new Thread(cGroup, this);
System.out.println("Starting " + t2.getName() + "...");
t2.start();
// checking the access for these ThreadGroups.
try {
pGroup.checkAccess();
System.out.println(pGroup.getName() + " has access");
cGroup.checkAccess();
System.out.println(cGroup.getName() + " has access");
} catch (SecurityException ex) {
System.out.println("No access: " + ex.toString());
}
// block until the other threads finish
t1.join();
t2.join();
} catch (InterruptedException ex) {
System.out.println(ex.toString());
}
}
// implements run()
public void run() {
for(int i = 0;i<1000;i++) {
i++;
}
System.out.println(Thread.currentThread().getName() + " finished executing");
}
}
让我们编译并运行上面的程序,这将产生以下结果 -
Starting Thread-0...
Starting Thread-1...
Parent ThreadGroup has access
Child ThreadGroup has access
Thread-0 finished executing
Thread-1 finished executing