问题描述

我在我的程序中创建了一个网格.下面是用于创建网格的代码.

I have created a grid in my program. Below is the code used to create the grid.

import java.awt.Graphics;

import javax.swing.JComponent;
import javax.swing.JFrame;

class Grid extends JComponent {
    public void paint(Graphics g) {
        g.drawRect (10, 10, 800, 500);    

        for (int i = 10; i <= 800; i+= 10)
            g.drawLine (i, 10, i, 510);

        for (int i = 10; i <= 500; i+= 10)
            g.drawLine (10, i, 810, i);
    }
}

public class CoreControl {

    public static void main(String[] a) {
        JFrame window = new JFrame();
        window.setSize(840,560);
        window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        window.getContentPane().add(new Grid());
        window.setVisible(true);
    }

}

我想做的是创建一个函数，该函数将根据我给它的坐标绘制一个矩形(用黑色填充).基本上我想用黑色填充网格的某些单元格，我的想法是在单元格坐标上绘制黑色填充矩形.如何实现这个功能?

What I want to do is to create a function which will draw a rectangle (filled with black color) based on the coordinates that I give it. Basically I want to populate certain cells of the grid with black color and my idea is to draw black filled rectangles on the cell coordinates. How do I make this function?

我尝试创建另一个名为 drawRectangle 的类并在主函数中调用它，例如 window.getContentPane().add(new drawRectangle());但这不起作用(只显示 drawRectangle 而不是网格).

I tried making another class called drawRectangle and called it in the main function like so window.getContentPane().add(new drawRectangle()); however that did not work (only drawRectangle shows up and not the grid).

我还希望能够反复使用此功能来不断创建矩形.

I also want to be able to use this function repeatedly to keep creating rectangles.

如何创建这个函数?

另外，如果您知道我应该构建这个程序的更好方法，请告诉我(我是 Java 新手，所以我愿意接受任何建议).

Also if you know a better way that I should structure this program please let me know (I am new to Java so I am open to any suggestions).

推荐答案

1. 不要使用paint，使用paintComponent并且不要忘记调用super.paintComponent
2. JComponent 可能不是最佳选择，JPanel 可能是更好的选择
3. Graphics#fillRect(int, int, int, int)?

1. Don't use paint, use paintComponent and don't forget to call super.paintComponent
2. JComponent may not be the best choice, JPanel is probably a better choice
3. What's wrong with Graphics#fillRect(int, int, int, int)?

您可以看看 Performing Custom Painting 和 2D 图形了解更多详情.

You might to take a look at Performing Custom Painting and 2D Graphics for more details.

我建议不要尝试使用第二个组件来执行填充.只需在网格类中提供一个方法，该方法提供单元格的 x/y 位置(以网格形式)并在 paintComponent 方法中填充单元格

I'd advice against trying to have a second component to performing the filling. Simply provide a method in you grid class that supplies the cell's x/y position (in grid terms) and fill the cell within the paintComponent method

更新示例

import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Point;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class CoreControl {

    public static class Grid extends JPanel {

        private List<Point> fillCells;

        public Grid() {
            fillCells = new ArrayList<>(25);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            for (Point fillCell : fillCells) {
                int cellX = 10 + (fillCell.x * 10);
                int cellY = 10 + (fillCell.y * 10);
                g.setColor(Color.RED);
                g.fillRect(cellX, cellY, 10, 10);
            }
            g.setColor(Color.BLACK);
            g.drawRect(10, 10, 800, 500);

            for (int i = 10; i <= 800; i += 10) {
                g.drawLine(i, 10, i, 510);
            }

            for (int i = 10; i <= 500; i += 10) {
                g.drawLine(10, i, 810, i);
            }
        }

        public void fillCell(int x, int y) {
            fillCells.add(new Point(x, y));
            repaint();
        }

    }

    public static void main(String[] a) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                Grid grid = new Grid();
                JFrame window = new JFrame();
                window.setSize(840, 560);
                window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                window.add(grid);
                window.setVisible(true);
                grid.fillCell(0, 0);
                grid.fillCell(79, 0);
                grid.fillCell(0, 49);
                grid.fillCell(79, 49);
                grid.fillCell(39, 24);
            }
        });
    }
}

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