將元素添加到線程的矢量並打印它們 - Java

Question

我的目標是啓動三個未同步的線程並讓它們各自添加一千個元素。這些元素需要存儲在一個集合中（我選擇Vector）然後打印。出於某種原因，我沒有獲得要打印的元素。我試圖解決打印方法和創建元素的方法。任何幫助表示讚賞。

import java.util.HashSet; 
import java.util.Iterator; 
import java.util.Set; 
import java.util.Vector; 

public class MyRun implements Runnable{ 
    int global = 0; 
    //create sets 
    static Vector t1v = new Vector(); 
    static Vector t2v = new Vector(); 
    static Vector t3v = new Vector();   
    public void run() { 
     action1(); 
    } 
    public void action1() { 
     for(int i = 0; i < 1000; i++) { 
      global++; 
      int x = global; 
      String tName = Thread.currentThread().getName(); 
      if(tName == "t1") { 
       t1v.addElement(x); 
       System.out.println(t1v.elementAt(x)); 
      } 
      if(tName == "t2") { 
       t2v.addElement(x); 
      } 
      if(tName == "t3") { 
       t3v.addElement(x); 
      }   
      //System.out.println("thread: " + tName + "counter is: " + global); 
     } 
     } 
    public static Vector gett1v() { 
     return t1v; 
    } 

    public static Vector gett2v() { 
     return t2v; 
    } 

    public static Vector gett3v() { 
     return t3v; 
    } 

} 

class ThreadTest{ 

    public static void main(String[] args) { 
     //create threads 
     Runnable threadJob = new MyRun(); 
     Thread t1 = new Thread(threadJob); 
     t1.setName("thread1"); 
     Thread t2 = new Thread(threadJob); 
     t2.setName("thread2"); 
     Thread t3 = new Thread(threadJob); 
     t3.setName("thread3"); 


     t1.start(); 
     t2.start(); 
     t3.start(); 

     Vector th1v = MyRun.gett1v(); 
     Vector th2v = MyRun.gett2v(); 
     Vector th3v = MyRun.gett3v(); 
     //MyRun.printSets(); 
     for(int i=0; i < th1v.size(); i++) { 
      System.out.println("Thread 1: " + th1v.elementAt(i)); 
     } 

     for(int i=0; i < th2v.size(); i++) { 
      System.out.println("Thread 2: " + th2v.elementAt(i)); 
     } 


     for(int i=0; i < th3v.size(); i++) { 
      System.out.println("Thread 3: " + th3v.elementAt(i)); 
    } 
    } 
} 

Answer 1

我冒昧地修改了一下你的代碼。

import java.util.HashSet; 
import java.util.Iterator; 
import java.util.Set; 
import java.util.Vector; 
import java.util.concurrent.atomic.AtomicInteger; 

public class MyRun implements Runnable{ 
    AtomicInteger global = new AtomicInteger(0); 
    //create sets 
    static Vector t1v = new Vector(); 
    static Vector t2v = new Vector(); 
    static Vector t3v = new Vector();   
    public void run() { 
     action1(); 
    } 
    public void action1() { 
     for(int i = 0; i < 1000; i++) { 
      global.incrementAndGet(); 
      int x = global.get(); 
      String tName = Thread.currentThread().getName(); 
      if(tName == "t1") { 
       t1v.addElement(x); 
      } 
      if(tName == "t2") { 
       t2v.addElement(x); 
      } 
      if(tName == "t3") { 
       t3v.addElement(x); 
      }   
      //System.out.println("thread: " + tName + "counter is: " + global); 
     } 
     } 
    public static Vector gett1v() { 
     return t1v; 
    } 

    public static Vector gett2v() { 
     return t2v; 
    } 

    public static Vector gett3v() { 
     return t3v; 
    } 

} 

class ThreadTest{ 

    public static void main(String[] args) { 
     //create threads 
     Runnable threadJob = new MyRun(); 
     Thread t1 = new Thread(threadJob); 
     t1.setName("t1"); 
     Thread t2 = new Thread(threadJob); 
     t2.setName("t2"); 
     Thread t3 = new Thread(threadJob); 
     t3.setName("t3"); 


     t1.start(); 
     t2.start(); 
     t3.start(); 

     try{ 
      t1.join(); 
      t2.join(); 
      t3.join(); 

     }catch(InterruptedException e){} 
     Vector th1v = MyRun.gett1v(); 
     Vector th2v = MyRun.gett2v(); 
     Vector th3v = MyRun.gett3v(); 
     //MyRun.printSets(); 
     System.out.println(th1v.size()+" "+th2v.size()+" "+th3v.size()); 
     for(int i=0; i < th1v.size(); i++) { 
      System.out.println("Thread 1: " + th1v.elementAt(i)); 
     } 

     for(int i=0; i < th2v.size(); i++) { 
      System.out.println("Thread 2: " + th2v.elementAt(i)); 
     } 


     for(int i=0; i < th3v.size(); i++) { 
      System.out.println("Thread 3: " + th3v.elementAt(i)); 
    } 
    } 
} 

幾點需要注意：

• 主線程是獨立的T1，T2，T3線程的，所以如果你想 得到的結果使用join（）方法或使用FutureTask或 的ExecutorService。提交（Runnable r）。所以主線程將等待所有三個線程完成，然後執行for循環。 因爲主線程沒有在等待，所以你得到一個空輸出。

• 使用原子類型，如果它們是多個增變線程，但只有一個增變線程，並且多讀線程使用volatile關鍵字，但使用volatile關鍵字會很昂貴。

希望幫助!!