Java ScheduledThreadPoolExecutor用法及代碼示例

// Java program to demonstrates ScheduleThreadPoolExecutor 
// class 
import java.util.*; 
import java.util.concurrent.*; 
import java.io.*; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // Creating a ScheduledThreadPoolExecutor object 
        ScheduledThreadPoolExecutor threadPool 
            = new ScheduledThreadPoolExecutor(2); 
  
        // Creating two Runnable objects 
        Runnable task1 = new Command("task1"); 
        Runnable task2 = new Command("task2"); 
  
        // Printing the current time in seconds 
        System.out.println( 
            "Current time : "
            + Calendar.getInstance().get(Calendar.SECOND)); 
  
        // Scheduling the first task which will execute 
        // after 2 seconds 
        threadPool.schedule(task1, 2, TimeUnit.SECONDS); 
  
        // Scheduling the second task which will execute 
        // after 5 seconds 
        threadPool.schedule(task2, 5, TimeUnit.SECONDS); 
  
        // Remember to shut sown the Thread Pool 
        threadPool.shutdown(); 
    } 
} 
  
// Class that implements the Runnable interface 
class Command implements Runnable { 
    String taskName; 
    public Command(String taskName) 
    { 
        this.taskName = taskName; 
    } 
    public void run() 
    { 
        System.out.println( 
            "Task name : " + this.taskName + " Current time: "
            + Calendar.getInstance().get(Calendar.SECOND)); 
    } 
}

// Java program to demonstrates ScheduleThreadPoolExecutor 
// class 
import java.util.*; 
import java.util.concurrent.*; 
import java.io.*; 
  
class GFG { 
    public static void main(String[] args) 
    { 
  
        // Creating a ScheduledThreadPoolExecutor object 
        ScheduledThreadPoolExecutor threadPool 
            = new ScheduledThreadPoolExecutor(2); 
  
        // Creating two Runnable objects 
        Runnable task1 = new Command("task1"); 
        Runnable task2 = new Command("task2"); 
  
        // Printing the current time in seconds 
        System.out.println( 
            "Current time:"
            + Calendar.getInstance().get(Calendar.SECOND)); 
  
        // Scheduling the first task which will execute 
        // after 2 seconds and then repeats periodically with 
        // a period of 8 seconds 
        threadPool.scheduleAtFixedRate(task1, 2, 8, 
                                       TimeUnit.SECONDS); 
  
        // Scheduling the second task which will execute 
        // after 5 seconds and then there will be a delay of 
        // 5 seconds between the completion 
        // of one execution and the commencement of the next 
        // execution 
        threadPool.scheduleWithFixedDelay(task2, 5, 5, 
                                          TimeUnit.SECONDS); 
  
        // Wait for 30 seconds 
        try { 
            Thread.sleep(30000); 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
  
        // Remember to shut sown the Thread Pool 
        threadPool.shutdown(); 
    } 
} 
  
// Class that implements Runnable interface 
class Command implements Runnable { 
    String taskName; 
    public Command(String taskName) 
    { 
        this.taskName = taskName; 
    } 
    public void run() 
    { 
        try { 
            System.out.println("Task name : "
                               + this.taskName 
                               + " Current time : "
                               + Calendar.getInstance().get( 
                                     Calendar.SECOND)); 
            Thread.sleep(2000); 
            System.out.println("Executed : " + this.taskName 
                               + " Current time : "
                               + Calendar.getInstance().get( 
                                     Calendar.SECOND)); 
        } 
        catch (Exception e) { 
            e.printStackTrace(); 
        } 
    } 
}