在Java的GUI编程中，如何在框架中显示饼图？
以下示例显示如何通过根据切片使Slices类和创建弧来显示饼图。
package com.yiibai;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
import javax.swing.JFrame;
class Slice {
double value;
Color color;
public Slice(double value, Color color) {
this.value = value;
this.color = color;
}
}
class MyComponent2 extends JComponent {
Slice[] slices = { new Slice(5, Color.black), new Slice(33, Color.green), new Slice(20, Color.yellow),
new Slice(15, Color.red) };
MyComponent2() {
}
public void paint(Graphics g) {
drawPie((Graphics2D) g, getBounds(), slices);
}
void drawPie(Graphics2D g, Rectangle area, Slice[] slices) {
double total = 0.0D;
for (int i = 0; i < slices.length; i++) {
total += slices[i].value;
}
double curValue = 0.0D;
int startAngle = 0;
for (int i = 0; i < slices.length; i++) {
startAngle = (int) (curValue * 360 / total);
int arcAngle = (int) (slices[i].value * 360 / total);
g.setColor(slices[i].color);
g.fillArc(area.x, area.y, area.width, area.height, startAngle, arcAngle);
curValue += slices[i].value;
}
}
}
public class DisplayPieChart {
public static void main(String[] argv) {
JFrame frame = new JFrame();
frame.getContentPane().add(new MyComponent2());
frame.setSize(300, 200);
frame.setVisible(true);
}
}
上述代码示例将产生以下结果。
示例-2
以下是在框架中显示饼图的另一个示例。
package com.yiibai;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JComponent;
import javax.swing.JFrame;
class Part2 {
double value;
Color color;
public Part2(double value, Color color) {
this.value = value;
this.color = color;
}
}
class MyComponent3 extends JComponent {
Part2[] slices = { new Part2(15, Color.yellow), new Part2(30, Color.white), new Part2(25, Color.blue),
new Part2(30, Color.red) };
MyComponent3() {
}
public void paint(Graphics g) {
drawPie((Graphics2D) g, getBounds(), slices);
}
void drawPie(Graphics2D g, Rectangle area, Part2[] slices) {
double total = 0.0D;
for (int i = 0; i < slices.length; i++) {
total += slices[i].value;
}
double curValue = 0.0D;
int startAngle = 0;
for (int i = 0; i < slices.length; i++) {
startAngle = (int) (curValue * 360 / total);
int arcAngle = (int) (slices[i].value * 360 / total);
g.setColor(slices[i].color);
g.fillArc(area.x, area.y, area.width, area.height, startAngle, arcAngle);
curValue += slices[i].value;
}
}
}
public class DisplayPieChart2 {
public static void main(String[] argv) {
JFrame frame = new JFrame();
frame.getContentPane().add(new MyComponent3());
frame.setSize(300, 200);
frame.setVisible(true);
}
}
上述代码示例将产生以下结果。
