在JPanel上繪製圖像並將其添加到JFrame

Question

我是初學java的高中生，我必須製作一個簡單的盒子和鬍鬚。我無法得到我在JPanel上繪製的東西以顯示在JFrame上。該圖只是不顯示。任何人都可以幫我嗎？

public class BoxPlot extends JFrame { 

public final int MIN; 
public final double Q1; 
public final double MEDIAN; 
public final double Q3; 
public final int MAX; 

public BoxPlot(int[] data){ 
    this.setLayout(new GridBagLayout()); 

    this.MIN = Statistics.min(data); 
    this.Q1 = Statistics.lowerQuartile(data); 
    this.MEDIAN = Statistics.median(data); 
    this.Q3 = Statistics.upperQuartile(data); 
    this.MAX = Statistics.max(data); 

    this.addBox(data); 
    this.addSummary(); 

    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    this.setSize(800, 600); 
    this.setResizable(true); 
    this.setVisible(true); 
} 

// Adds a panel with the boxplot 
private void addBox(int[] data) { 
    Box box = new Box(data); 
    GridBagConstraints c = new GridBagConstraints(); 
    c.gridx = 0; 
    c.gridy = 0; 
    c.weighty = 1; 
    this.add(box, c); 
} 

// Adds a panel with the five number summaries as JLabels 
// to the bottom of the JFrame 
private void addSummary() { 
    JPanel summary = new JPanel(); 
    summary.setLayout(new GridLayout()); 
    JLabel l = new JLabel("Minimum: "+this.MIN, JLabel.CENTER); 
    summary.add(l); 
    l = new JLabel("First Quartile: "+this.Q1, JLabel.CENTER); 
    summary.add(l); 
    l = new JLabel("Median: "+this.MEDIAN, JLabel.CENTER); 
    summary.add(l); 
    l = new JLabel("Third Quartile: "+this.Q3, JLabel.CENTER); 
    summary.add(l); 
    l = new JLabel("Maximum: "+this.MAX, JLabel.CENTER); 
    summary.add(l); 
    GridBagConstraints c = new GridBagConstraints(); 
    c.gridx = 0; 
    c.gridy = 1; 
    c.weightx = 1; 
    c.ipady = 10; 
    c.fill = GridBagConstraints.HORIZONTAL; 
    c.anchor = GridBagConstraints.PAGE_END; 
    this.add(summary, c); 
} 

``

public class Box extends JPanel{ 

private int min; 
private double q1; 
private double median; 
private double q3; 
private int max; 

public Box(int[] data) { 
    this.min = Statistics.min(data); 
    this.q1 = Statistics.lowerQuartile(data); 
    this.median = Statistics.median(data); 
    this.q3 = Statistics.upperQuartile(data); 
    this.max = Statistics.max(data); 
} 

// paints the box onto the JPanel 
public void paintComponent(Graphics g){ 
    int d1 =10 * (int) (this.q1-this.min); 
    int d2 =10 * (int) (this.median-this.q1); 
    int d3 =10 * (int) (this.q3-this.median); 
    int d4 =10 * (int) (this.max-this.q3); 
    g.drawLine(100, 150, 100+d1, 150); 
    g.drawLine(100+d1+d2+d3, 150, 100+d1+d2+d3+d4, 150); 
    g.setColor(Color.RED); 
    g.fillRect(100+d1, 100, d2, 100); 
    g.setColor(Color.BLUE); 
    g.fillRect(100+d1+d2, 100, d3, 100); 
} 

Answer 1

你必須爲你的Box組件設置沒有GridBagConstraints填充值，因此該組件將有效地沒有大小。

你可以使用：

c.fill = GridBagConstraints.BOTH;