java - 我们如何绘制这个饼图类？

Question

我们不太清楚如何让这个饼图出现:

import java.awt.*;
import java.awt.Graphics2D;
import java.awt.Graphics;
import javax.swing.*;


public class PieChart extends View {

    public PieChart (Model model){
        super(model);
        MyComponent piechart = new MyComponent();
        this.add(piechart);
    }
    public void updateView(){
        repaint();
    }
}

class MyComponent extends JComponent {
    Slice[] slices = {
            new Slice(5, Color.black), new Slice(33, Color.green), new Slice(20, Color.yellow), new Slice(15, Color.red)
    };

    MyComponent() {
        setVisible(true);
    }

    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[1].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;
        }
    }
}

class Slice {
    double value;
    Color color;
    public Slice(double value, Color color) {
        this.value = value;
        this.color = color;
    }
}

以及它从“view”扩展的类

import javax.swing.*;


@SuppressWarnings("serial")
public class View extends JPanel  {
    public Model model;

    public View(Model model)  {
        this.model=model;
        model.addView(this);
    }

    public void setModel(Model model) {
        this.model=model;
    }

    public Model getModel() {
        return model;
    }

    public void updateView() {
        repaint();
    }
}

最后是调用所有 View 的类(仅显示适用的代码)

public class Simulator {

    ....
    private View pieChart;

    public Simulator(int floors, int rows, int places) {
        //initialiseert Model
        floornumber = floors;
        rownumber = rows;
        placenumber = places;

        model=new Model(floornumber,rownumber,placenumber);

        screen=new JFrame("Parkere simulatie");
        screen.setTitle("Parkeer-control Screen");
        screen.setSize(1600, 1000);
        screen.setResizable(false);
        screen.setLayout(null);
        ........

        pieChart = new PieChart(model);
        screen.getContentPane().add(pieChart);
        pieChart.setBounds(840, 300, 300, 300);
    }
}

我认为问题出在paint()方法上。我们不能从其他地方调用它，但我很确定我们应该以不同的方式调用它，因为它是一个面板而不是一个框架。有谁知道我们如何解决这个问题？

Answer 1

您没有在屏幕上显示“屏幕”。 (例如setVisible)——它会根据需要自动调用子项的paint

再次:使框架可见， children 将被框架绘制