在構造函數中的「this」對象和CurrentThread之間

Question

在對多線程做一些實踐的時候，我發現我不能在我的代碼中設置線程的名字。我可以使用this來引用當前對象，那麼爲什麼我在構造線程來訪問當前線程時無法使用Thread.currentThread。我有點困惑。請幫幫我。

實際創建線程時？是在構建線程實例時還是在線程上調用方法start（）時？

currentThread是什麼意思？

public class RecursiveRunnableTest { 

    public static void main(String... args){ 
     Thread t = new Thread(new RecursiveRunnable("First thread")); 
     t.start(); 
    } 


} 

class RecursiveRunnable implements Runnable { 

    private String name; 
    public RecursiveRunnable(String name) { 
     this.name = name; 
     Thread.currentThread().setName(this.name); // Expecting to set the name of thread here 
    } 
    @Override 
    public synchronized void run() { 
     System.out.println(Thread.currentThread().getName()); // displaying Thread-0 
     System.out.println(this.name); // displaying "First thread" 

     try{ 
      Thread.sleep(5000); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     }finally{ 

     } 
    } 
} 

Answer 1

嘗試做這個，而不是

Thread t = new Thread(new RecursiveRunnable("First thread")); 
t.start(); 
Thread.sleep(1L); 
System.out.println("main thread: " + Thread.currentThread().getName()); // same thread that created the RecrusiveRunnable instance 

你會看到

main thread: First thread 

打印。 這是因爲主線程構建RecursiveRunnable，所以

Thread.currentThread().setName(this.name); 

實際上是改變了主線程的名稱，而不是線程的Runnable最終會運行。

---

而且

System.out.println(this.name); // displaying "First thread" 

指的是RecursiveRunnable對象的name字段，它你已經設置爲與主線程相同的值。

Answer 2

只是因爲主線程構造它不是t線程構造自己。所以，你可以重寫這一個（開始前設置線程的名稱）：

public class RecursiveRunnableTest { 

    public static void main(String... args){ 
     RecursiveRunnable rr = new RecursiveRunnable("First thread"); 
     Thread t = new Thread(rr); 
     t.setName(rr.getName()); 
     t.start(); 
    } 


} 

class RecursiveRunnable implements Runnable{ 

    private String name; 
    public RecursiveRunnable(String name) { 
     this.name = name; 
    } 
    public String getName(){return this.name;} 
    @Override 
    public synchronized void run() { 
     System.out.println(Thread.currentThread().getName()); // displaying Thread-0 
     System.out.println(this.name); // displaying "First thread" 

     try{ 
      Thread.sleep(5000); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     }finally{ 

     } 
    } 
}