Java 我有两个类，想要从一个类到另一个类得到一个变量

我有两节课。画啊画啊。在DrawGUI中，我有一个JPanel。对于我的JUnit测试，我需要为getWidth（）和getHeight（）请求类Draw。因此，我的代码如下所示：

public class Draw {
public static void main(String[] args) throws ColorException {new Draw();}

/** Application constructor:  create an instance of our GUI class */
  public Draw() throws ColorException { window = new DrawGUI(this); }

  protected JFrame window;

  public void getWidth(){
  }


}

class DrawGUI extends JFrame {
  JPanel drawPanel;

  public DrawGUI(Draw application) throws ColorException {
    super("Draw");        // Create the window
    app = application;

    drawPanel = new JPanel();
  }
}

---

那么如何实现getWidth呢？getWidth应该从JPanel drawPanel返回宽度

一个选项是更改保存

窗口的弱类型

：

public class Draw {
    public static void main(String[] args) throws ColorException {new Draw();}

    /** Application constructor:  create an instance of our GUI class */
    public Draw() throws ColorException { window = new DrawGUI(this); }

    protected DrawGUI window;  // <- is now a DrawGUI

    public int getWidth(){
        return window.getPanelWidth();
    }

}

class DrawGUI extends JFrame {
    JPanel drawPanel;
    ...

    public DrawGUI(Draw application) throws ColorException {
        super("Draw");        // Create the window
        app = application;

        drawPanel = new JPanel();
    }

    public int getPanelWidth() {  // <- added method to get panel width
        return drawPanel.getWidth();
    }
}

公共类绘图{
公共静态void main（字符串[]args）抛出ColorException{new Draw（）；}
/**应用程序构造函数：创建GUI类的实例*/
public Draw（）抛出ColorException{window=new DrawGUI（this）；}
受保护的DrawGUI窗口；//
返回窗口。getWidth（）；
？@jornverne我希望从JPanel DrawPanel获取getWidth，而不是整个窗口。