Java 初学者swing递归
第一次在这里发布。这项编程作业让我难堪,代码如下:Java 初学者swing递归,java,swing,recursion,Java,Swing,Recursion,第一次在这里发布。这项编程作业让我难堪,代码如下: import java.awt.*; import javax.swing.*; public class HTree extends JPanel { private Color color = new Color((int)(Math.random() * 256), (int)(Math.random() * 256), (int)(Math.random() * 256)); public void draw(Graphics g
import java.awt.*;
import javax.swing.*;
public class HTree extends JPanel {
private Color color = new Color((int)(Math.random() * 256), (int)(Math.random() * 256), (int)(Math.random() * 256));
public void draw(Graphics g, int n, double sz, double x, double y) {
if (n == 0) return;
double x0 = x - sz/2, x1 = x + sz/2;
double y0 = y - sz/2, y1 = y + sz/2;
// draw the 3 line segments of the H
g.setColor(color);
g.drawLine((int)x0, (int)y, (int)x1, (int)y);
g.drawLine((int)x0, (int)y0, (int)x0, (int)y1);
g.drawLine((int)x1, (int)y0, (int)x1, (int)y1);
// recursively draw 4 half-size
// H-trees of order n-1
g.setColor(color);
draw(g, n-1, sz/2, x0, y0);
draw(g, n-1, sz/2, x0, y1);
draw(g, n-1, sz/2, x1, y0);
draw(g, n-1, sz/2, x1, y1);
repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
draw(g, 3, .5, .5, .5);
}
public static void main(String[] args) {
HTree h = new HTree();
JFrame application = new JFrame("HTree");
application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
application.add(h);
application.setSize(1000, 1000);
application.setVisible(true);
}
}
它编译正确,但在运行程序时,我得到的只是一个空JFrame。我对swing不太熟悉,但我认为问题在于要么HTree构造函数错误,要么我可能需要在main中调用draw(),但不确定如何使用图形对象调用它。非常感谢您的帮助,谢谢 一些观察结果:
- 使用相对于面板当前大小的整数坐标
- 替代以建立初始几何图形
- 使用
获得明亮、饱和的颜色;考虑创建一个色域,在每个级别选择不同的颜色。Color.getHSBColor()
- 仅在上构造和操作Swing GUI对象
- 考虑使用
或JSpinner
以交互方式控制递归深度,如建议和所示JSlider
- 不要递归调用
;使用它来计划对repaint()
实现的调用,就像当递归深度响应某些输入时一样paintComponent()
- 考虑使用
和呈现提示,如图所示setStroke()
- 考虑使用,每次调用
时,将递归深度增加一级ActionListener
谢谢到目前为止:仍然不确定如何从args[0]传递递归次数,但使用了用户输入实例变量。我能够使用数组将每个递归设置为随机颜色,并使用g.fillRect.Excellent使线条变粗;我在上面又添加了一些建议。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
/**
* @see https://stackoverflow.com/a/37450393/230513
*/
public class HTree {
private void display() {
JFrame f = new JFrame("HTree");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(new Tree());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private static class Tree extends JPanel {
private final Color color = Color.getHSBColor((float) Math.random(), 1, 1);
public void draw(Graphics g, int n, double sz, double x, double y) {
if (n == 0) {
return;
}
double x0 = x - sz / 2, x1 = x + sz / 2;
double y0 = y - sz / 2, y1 = y + sz / 2;
// draw the 3 line segments of the H
g.setColor(color);
g.drawLine((int) x0, (int) y, (int) x1, (int) y);
g.drawLine((int) x0, (int) y0, (int) x0, (int) y1);
g.drawLine((int) x1, (int) y0, (int) x1, (int) y1);
// recursively draw 4 half-size
// H-trees of order n-1
g.setColor(color);
draw(g, n - 1, sz / 2, x0, y0);
draw(g, n - 1, sz / 2, x0, y1);
draw(g, n - 1, sz / 2, x1, y0);
draw(g, n - 1, sz / 2, x1, y1);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
draw(g, 3, getWidth() / 2, getWidth() / 2, getHeight() / 2);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(500, 500);
}
public static void main(String[] args) {
EventQueue.invokeLater(new HTree()::display);
}
}
}