小编Mic*_*ael的帖子

我在Java重写方面有点困惑.假设我们有以下继承:

class A{
    public A(){    
    }

    void show(){
        System.out.println("SuperClass");
    }
}

class B extends A{

    @Override
    void show(){
        System.out.println("SubClass");
    }

}

public class Test {

    public static void main(String[] args) {
      B b = new B();
      b.show();
    }  
}

显然,class B覆盖了show()由class A.继承的方法.为什么不b.show();打印消息System.out.println("SuperClass");,因为class B现在的方法show()来自class A？

谢谢.

我需要将给定的任何图像转换为字节数组以满足加密要求.我正在使用JProgressBar来监控转换进度,以防所选图像很大:

File p= new File("C:\");
BufferedImage oImg = ImageIO.read(p);
ByteArrayOutputStream ba = new ByteArrayOutputStream();
ImageIO.write(oImg, "jpg", ba);
ba.flush();

ProgressBar pb = new ProgressBar();
Thread thread = new Thread(pb);
thread.join();
pb.fireTask(ba.toByteArray());

我定义了一个ProgressBar使用SwingWorker如下的类:

public class ProgressBar extends JPanel implements Runnable {

    private JProgressBar progressBar;
    private Task task;
    private byte[] imgByteArray;


    public void run() {
        createGUI();
    }

    // Create the GUI
    private void createGUI() {

        JFrame frame = new JFrame("Converting...");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JComponent newContentPane = new ProgressBar();
        newContentPane.setOpaque(true); 
        frame.setContentPane(newContentPane);

        JPanel …