矩阵方括号

Question

我使用的是JavaSwing，我需要显示一个带有方括号的矩阵（普通方括号，就像我们在数学中使用的跨越多行的方括号），矩阵大小不是固定的，它取决于输入。

下面是我用来显示矩阵的代码：

public static void printMatrix(String[][] matrix) {
        String output = "";
        for (int x = 0; x < matrix.length; x++) {
            output += Arrays.toString(matrix[x]) + "\n";
        }
        JOptionPane.showMessageDialog(null, output, "Matrix",
                JOptionPane.INFORMATION_MESSAGE);
    }

所以我正在搜索如何做到这一点，我找到了这个链接https://docs.oracle.com/javase/tutorial/uiswing/components/border.html但它不包含我需要的括号，也找到了这个https://team.mumie.net/mumie/mathletfactory_lib_apidocs/net/mumie/mathletfactory/display/noc/matrix/MatrixBorder.html#MatrixBorder（java.awt.组件，int），但我没有找到任何例子如何使用它。

Answer 1

根据nIcE cOw对我上述评论之一的回答，您需要创建自己的CustomBorder类，该类扩展AbstractBorder，并重写其paintBorder（）方法来绘制括号的每个部分。

在本例中，我将此任务分为三部分，上/下/左

internalGap变量是内容和边框之间的空间

以下是一些输出的屏幕截图：

包含2、6和10个元素

产生上述输出的代码是：

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Insets;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.AbstractBorder;

public class EquationMatrixBorder {

    private JPanel pane;
    private CustomBorder customBorder;
    private static final int ROWS_AND_COLS = 1;

    private void displayGUI() {
        JFrame frame = new JFrame("Custom Border Example");

        customBorder = new CustomBorder(Color.RED, 15, 10);
        pane = new JPanel();
        
        pane.setLayout(new GridLayout(ROWS_AND_COLS, ROWS_AND_COLS, 15, 15));
        //Used to fill the grid, not relevant to question
        Random random = new Random();
        for (int i = 0; i < ROWS_AND_COLS; i++) {
            for (int j = 0; j < ROWS_AND_COLS; j++) {
                int r = 0;
                if (j % 2 == 0) {
                    r = random.nextInt(2);
                } else {
                    r = random.nextInt(2) - 1;
                }
                pane.add(new JLabel(String.valueOf(r)));
            }
        }
        
        pane.setBorder(customBorder);
        frame.add(pane);
        frame.pack();
        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }

    public static void main(String[] args) {
        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                new EquationMatrixBorder().displayGUI();
            }
        };
        EventQueue.invokeLater(runnable);
    }
}

class CustomBorder extends AbstractBorder {
    
    private Color color;
    private int gap;
    private int bracketsTopAndBottom = 10;
    private int internalGap;
    
    public CustomBorder(Color color, int gap, int internalGap) {
        this.color = color;
        this.gap = gap;
        this.internalGap = internalGap;
    }
    
    @Override
    public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
        super.paintBorder(c, g, x, y, width, height);
        Graphics2D g2d = null;
        if (g instanceof Graphics2D) {
            g2d = (Graphics2D) g;
            g2d.setColor(color);
            g2d.setStroke(new BasicStroke(3));
            
            //top part of brackets
            g2d.drawLine(x + gap, y + gap, x + gap + bracketsTopAndBottom, (y +  gap));
            g2d.drawLine(width - x - gap - bracketsTopAndBottom, y + gap, width - gap - x, (y +  gap));
            
            //bottom part of brackets
            g2d.drawLine(x + gap, height - gap, x + gap + bracketsTopAndBottom, height - gap);
            g2d.drawLine(width - x - gap - bracketsTopAndBottom, height - gap, width - gap - x, height - gap);
            
            //left and right part of brackets
            g2d.drawLine(x + gap, y + gap, x + gap, height - gap);
            g2d.drawLine(width - x - gap, y + gap, width - x - gap, height - gap);
        }
    }
    
    @Override
    public Insets getBorderInsets(Component c) {
        return getBorderInsets(c, new Insets(gap, gap, gap, gap));
    }
    
    @Override
    public Insets getBorderInsets(Component c, Insets insets) {
        insets.left = insets.top = insets.right = insets.bottom = gap + internalGap;
        return insets;
    }
}

我还并没有完成OP的期望输出中显示的行和列数，我将把它省略掉，因为这个问题只与方括号有关