Question

我创建了一个名为Robit的类（故意拼写错误），它使用paint(Graphics g)方法定义了一个正方形。我正在扩展JFrame，所有这些工作正常我只是不能让正方形绘制

import java.awt.*;

public class Robit {

int[] location = new int[4];
double[] vectors = new double[2];
Color mainColor;

    public Robit(Color color, int x) {
        mainColor = color;
        switch (x) {
            case 0:
                location[0] = 50;
                break;
            case 1:
                location[0] = 700;
                break;
            default:
                location[0] = 350;
                break;
        }
        location[1] = 400;
        location[2] = 50;
        location[3] = 50;

    }

    public void paint(Graphics g) {
        g.setColor(mainColor);
        g.fillRect(location[0], location[1], location[2], location[3]);

    }
    public int getX() {
        return location[0];
    }

    public int getY() {
        return location[1];
    }

}

`这就是我实例化的类，继承人在哪里实现它 import java.awt.Color; import javax.swing。*;

public class Frame extends JFrame {
    public Frame(){
        setLayout(null);


        Robit r1 = new Robit(Color.red, 0);
        Robit r2 = new Robit(Color.blue, 1);


    }
}

和主要课程

import javax.swing.JFrame;

public class App {

    public static void main(String[] args) {
        Frame f = new Frame();
        f.setSize(800, 450);
        f.setResizable(false);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.setVisible(true);

    }
}

Answer 1

您没有在paint课程中调用Robit方法。请尝试以下方法：

public class Frame extends JFrame {
   protected Robit r1;
   protected Robit r2;
   public Frame(){
       setLayout(null);

      r1 = new Robit(Color.red, 0);
      r2 = new Robit(Color.blue, 1);
   }

   public void paint(Graphics g)
   {
      super.paint(g);
      r1.paint(g);
      r2.paint(g); 
   }
}

使用paint实例化一个类来制作一个正方形

1 个答案: