Java ThreadGroup setMaxPriority()用法及代碼示例

ThreadGroup類setMaxPriority()方法

• setMaxPriority() 方法在 java.lang 包中可用。
• setMaxPriority() 方法用於分配此線程組的最大優先級，對已存在於此線程組中的更高優先級線程沒有影響。
• setMaxPriority() 方法是一個非靜態方法，它隻能通過類對象訪問，如果我們嘗試使用類名訪問方法，那麽我們將得到一個錯誤。
• setMaxPriority() 方法可能會在分配此 ThreadGroup 的優先級時拋出異常。
  SecurityException- 當前線程不允許更新此線程組時，可能會拋出此異常。

用法:

    public final void setMaxPriority(int prior);

參數：

• int prior- 代表這個線程組的新優先級。

返回值：

這個方法的返回類型是void- 它什麽都不返回。

例：

// Java program to demonstrate the example 
// of void setMaxPriority(int prior) method of ThreadGroup 

public class SetMaxPriority implements Runnable {
    public static void main(String[] args) {
        SetMaxPriority max_pri = new SetMaxPriority();
        max_pri.setPrio();
    }

    public void setPrio() {
        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");

            // By using setMaxPriority() method is to set the
            // maximum priority for both the thread group
            // 7 for base and 5 for derived thread group

            base.setMaxPriority(7);
            derived.setMaxPriority(5);

            // 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.....");
            th2.setPriority(10);

            // By using start() method is to start its execution 
            // of thread th2
            th2.start();

            // 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.....");
    }
}

輸出

Thread-0 begins.....
Thread-0 ends.....
Thread-1 begins.....
Thread-1 ends.....