在System.in上的readLine不掛上Swing GUI線程

Question

我有下面的代碼應該將System.in重定向到JTextField。但每當我嘗試new BufferedReader(new InputStreamReader(System.in)).readLine();時，Swing GUI都會掛起。我如何從System.in中讀取行而不掛上GUI線程？

private static LinkedBlockingQueue<Character> sb = new LinkedBlockingQueue<Character>(); 
BufferedInputStream s = new BufferedInputStream(new InputStream() { 
    int c = -1; 

    @Override 
    public int read() throws IOException { 
     Thread thread = new Thread(new Runnable() { 

      @Override 
      public void run() { 
       try { 
        c = sb.take(); 
       } catch (InterruptedException ie) { 
        ie.printStackTrace(); 
       } 
      } 
     }); 
     thread.start(); 
     try { 
      thread.join(); 
     } catch (InterruptedException e) { 
      e.printStackTrace(); 
     } 
     return c; 
    } 
}); 
JTextField t = new JTextField(); 
    t.addKeyListener(new KeyListener() { 
     @Override 
     public void keyTyped(final KeyEvent e) { 
      sb.offer(e.getKeyChar()); 
      if (e.getKeyChar() == '\n' || e.getKeyChar() == '\r') { 
       t.setText(""); 
      } 
     } 

     @Override 
     public void keyPressed(KeyEvent arg0) { 
     } 

     @Override 
     public void keyReleased(KeyEvent arg0) { 
     } 
    }); 

System.setIn(s); 

Answer 1

定義一個Callback類，在這裏我使用一個接口，可以跳過這個階段。

interface Callback { 
    void updateText(String s); 
} 

public class CallbackImpl implements Callback {// implements this interface so that the caller can call text.setText(s) to update the text field. 

    JTextField text;// This is the filed where you need to update on. 

    CallbackImpl(JTextField text){//we need to find a way for CallbackImpl to get access to the JTextFiled instance, say pass the instance in the constructor, this is a way. 
    this.text=text; 
    } 

    void updateText(String s){ 
     text.setText(s);//updated the text field, this will be call after getting the result from console. 
    } 
} 

定義執行作業的線程並在作業（從控制檯讀取）完成後調用回調方法。

class MyRunable implements Runnable { 

    Callback c; // need a callable instance to update the text filed 

    public MyRunable(Callback c) {// pass the callback when init your thread 
     this.c = c; 
    } 

    public void run() { 
     String s=// some work reading from System.in 
     this.c.updateText(s); // after everything is done, call the callback method to update the text to the JTextField. 
    } 

} 

要使其工作，你的聽衆，啓動這個線程：

new Thread(new MyRunable(new CallbackImpl(yourJtextFiled))).start();//start another thread to get the input from console and update it to the text field.