java - 图形代码的奇怪输出

Question

我正在尝试制作一个四子棋游戏来提高我的 Java 图形能力并作为一个学校项目。游戏的背景将是蓝色的 JPanel，游戏板将是一个单独的 JPanel，放置在背景之上。请参阅下面我的类(class):

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;


public class gameBoard extends JPanel {

private Board bored;

public gameBoard(){
    setLayout(new BorderLayout());

    bored = new Board();//does not appear in Center Region of gameBoard     
    add(bored, BorderLayout.CENTER);

    }

public void paint(Graphics g){//This line is the one that is acting weird.
    //blue rectangle board is here, but when repaint called
    //JFrame turns blue and does not add new JPanel called above
    g.setColor(Color.BLUE);
    g.fillRect(0, 0, 1456, 916);
    }

}

和

import java.awt.BasicStroke;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Color;
import java.awt.Graphics2D;
import javax.swing.JPanel;

public class Board extends JPanel {

/*
 * 2d array will represent board and take 1's(red) and 2's(black) the nums
 * represent pieces, with each redraw of the board, a check will be done to
 * compare a sum against blackWin and redWin. Sum will be created by
 * summing a continuous line of 1's or 2's going left -> right
 */
public int[][] boardEvalMatrix = new int[6][7];
private final int blackWin = 8, redWin = 4;


public Board() {//1200 x 764
    BoardMethods a = new BoardMethods();
    a.printBoard(getBoard());
    JPanel panelLORDY = new JPanel(new FlowLayout());
    repaint();
    }

public int[][] getBoard(){
    return boardEvalMatrix;
    }
public void paint(Graphics g){
    g.setColor(Color.BLUE);//Drawing background with actual board as a Test
    g.fillRect(0, 0, 1456, 916);//will not remain like this
    Graphics2D newG = (Graphics2D) g;
    newG.setStroke(new BasicStroke(15));
    g.setColor(Color.YELLOW);
    for(int a = 0; a < 6; a++)//rows for board --- rowHeight is 127
        g.drawRect(128, 68+ (a*127), 1200, 127);
    //g.setColor(Color.BLACK);
    //newG.setStroke(new BasicStroke(8));
    //for(int a = 0; a < 7; a++)//columns for board --- columnWidth is 171
    //  g.drawRect(208, 152, 70, 10);


    //g.drawLine(50,0, 1456, 916); //width 1456 length 916 - school computer monitors
    }
}

所以发生的事情是这样的:

问题 1:

当我在 gameBoard 类中包含 public void Paint(Graphics g) 行时，运行驱动程序时出现的显示只是灰色的 JFrame，即使没有调用 repaint() 并且 paint() 方法为空。但是，当我删除创建 paint 方法的行时，问题消失并出现正确的显示。

问题 2:

即使我将绘制蓝色矩形的代码放在 gameBoard 类的 paint 方法中并调用 repaint() ，JFrame 是蓝色的，这部分是正确的。我知道 Java 从上到下执行命令，所以我确保将实际游戏板添加到 gameBoard JPanel 的代码是在绘制蓝色矩形之后出现的，但它没有工作。

问题:

我做错了什么以及如何解决它？

Answer 1

要更改您刚刚使用的面板的背景颜色:

setBackground( Color.BLUE );

在面板上。那么就不需要定制绘画了。

当你覆盖 paint() 并忘记 super.paint() 时，你就真的搞乱了绘画过程。 paint() 方法负责在面板上绘制子组件。由于您不调用 super.paint() ，因此子级永远不会被绘制。

如果由于某种原因您确实需要自定义绘制，那么您应该重写 paintComponent() 方法，并且不要忘记调用 super.paintComponent()。不要重写paint()。

阅读有关“自定义绘画”的 Swing 教程，尤其是 A Closer Look at the Paint Mechanism 部分。了解更多信息和示例。