threadgroup

ThreadGroup類的checkAccess()方法 (ThreadGroup class checkAccess() method)

• checkAccess() method is available in java.lang package.

  checkAccess()方法在java.lang包中可用。

• checkAccess() method is used to check whether the currently running thread has permission to update the thread group or not.

  checkAccess()方法用于檢查當前正在運行的線程是否具有更新線程組的權限。

• checkAccess() method is not a static method so it is not accessible with the class name (i.e. this method is accessible with the class object only).

  checkAccess()方法不是靜態方法，因此無法使用類名進行訪問(即，只能使用類對象訪問此方法)。

• checkAccess() method is a final method so it is not overridable (i.e. this method is not overridable in child class).

  checkAccess()方法是最終方法，因此它不可重寫(即，該方法在子類中不可重寫)。

• This method may throw an exception at the time of accessing a thread group.

  訪問線程組時，此方法可能會引發異常。

  SecurityException: In this exception when the current thread is not authorized to access the thread group when the security manager exists.

  SecurityException：在存在安全管理器的情況下，當當前線程無權訪問線程組時，發生此異常。

Syntax:

句法：

    public final void checkAccess();

Parameter(s):

參數：

• This method does not accept any parameter.

  此方法不接受任何參數。

Return value:

返回值：

The return type of this method is void, it does not return anything.

此方法的返回類型為void ，它不返回任何內容。

Example:

例：

// Java program to demonstrate the example of 
// checkAccess () method of ThreadGroup Class.
import java.lang.*;
class CheckAccess extends Thread {
// Override run() of Thread class
public void run() {
String name = Thread.currentThread().getName();
System.out.println(name + " " + "finish executing");
}
}
public class Main {
public static void main(String[] args) {
CheckAccess ca = new CheckAccess();
try {
// We are creating an object of ThreadGroup class
ThreadGroup tg1 = new ThreadGroup("ThreadGroup 1");
ThreadGroup tg2 = new ThreadGroup("ThreadGroup 2");
// We are creating an object of Thread class and 
// we are assigning the ThreadGroup of both the thread
Thread th1 = new Thread(tg1, ca, "First Thread");
Thread th2 = new Thread(tg2, ca, "Second Thread");
// Calling start() method with Thread class object 
// of Thread class
th1.start();
th2.start();
// Here we are checking access of ThreadGroup
try {
tg1.checkAccess();
System.out.println(tg1.getName() + " " + "has access");
tg2.checkAccess();
System.out.println(tg2.getName() + " " + "has access");
} catch (SecurityException se) {
System.out.println(se.getMessage());
}
th1.join();
th2.join();
} catch (Exception ex) {
System.out.println(ex.getMessage());
}
}
}

Output

輸出量

E:\Programs>javac Main.java
E:\Programs>java Main
ThreadGroup 1 has access
ThreadGroup 2 has access
First Thread finish executing
Second Thread finish executing

翻譯自: https://www.includehelp.com/java/threadgroup-class-checkacess-method-with-example.aspx

threadgroup