如何从另一个类的main方法访问变量

Question

这可能是一个noob问题，但是哦，我需要从main方法中收集frameWidth和frameHeight变量

---

frame.java

public static void main(String[] args) { 
    .....
    .......                                                
    int frameWidth  = frame.getContentPane().getWidth();
    int frameHeight  = frame.getContentPane().getHeight();
}

Board.java

public class board extends JPanel {
    private frame Frame;

    public board() {
        Frame = new frame();
        int FrameWidth = frame.main().frameWidth;
        int FrameWidth = frame.main().frameHeight;
    }
}

---

访问变量的正确方法是什么？

Answer 1

将它传递给构造函数：

private int width = 0, height= 0;
public Board(int width, int height){
  ...
  this.width = width;
  this.height = height;
}

然后在你的main ：

Board myBoard = new Board(FrameWidth, FrameHeight);

您的类现在可以分别访问变量FrameWidth和FrameHeight作为width和height 。

Answer 2

你需要声明Main类中的board（类应该是大写B）对象，并为宽度和高度定义getter，如下所示：

public static void main(String[] args) { 
Board board = new Board();                                              
int frameWidth  = board.getWidth();
int frameHeight  = board.getHeight();
}

public class board extends JPanel {
private frame Frame;

public board() {
    Frame = new frame();
    int FrameWidth = frame.frameWidth;
    int FrameWidth = frame.frameHeight;
}
public int getWidth(){
     return frame.frameWidth;
}

public int getHeight(){
    return frame.frameHeight;

}
}