如何訪問變量外線程而不使變量成爲最終變量

Question

如何訪問變量外線程而不使變量成爲最終變量？

int x=0; 
Thread test = new Thread(){ 
public void run(){ 
x=10+20+20; //i can't access this variable x without making it final, and if i make  it.....     
       //final i can't assign value to it 
} 
};     
test.start(); 

Answer 1

理想情況下，你可能需要使用ExecutorService.submit(Callable<Integer>)，然後調用Future.get()獲得的價值。線程共享的變量變量需要同步動作，例如volatile，lock或​​關鍵字

Future<Integer> resultOfX = Executors.newSingleThreadExecutor().submit(new Callable<Integer>() { 
     @Override 
     public Integer call() throws Exception { 
      return 10 + 20 + 20; 
     } 
    }); 
    int x; 
    try { 
     x = resultOfX.get(); 
    } catch (InterruptedException ex) { 
     // never happen unless it is interrupted 
    } catch (ExecutionException ex) { 
     // never happen unless exception is thrown in Callable 
    }