如何从JList选项中绘制矩形

问题描述：

我正在寻找一些关于我正在编写的Java程序的帮助。我需要显示一个由矩形组成的简单条形图，该矩形基于保存在由JList选择事件生成的数组中的数据。但是，没有任何东西在JPanel中绘制，我无法弄清楚如何解决它。如何从JList选项中绘制矩形

列表框选择事件（参考）

try 
{ 
BufferedReader in = new BufferedReader((new FileReader("scores.txt"))); 

String sLine; 

while ((sLine = in.readLine()) != null) 
{ 
    vecAthlete.addElement(new Stage3_DataFile(sLine)); 
} 

String[] saAthlete = new String[vecAthlete.size()]; 
for (int iI = 0; iI < vecAthlete.size(); iI++) 
    saAthlete[iI] = vecAthlete.get(iI).sName; 
jList_Athlete.setListData(saAthlete); 
jList_Athlete.setSelectedIndex(0); 

// Reading input line by line 
// Close file 
    in.close(); 
} 
catch (IOException e) 
{ 
    System.out.println("ERROR: Could not read text file!"); 
} 
jList_Athlete.addListSelectionListener(new javax.swing.event.ListSelectionListener() 
{ 
    public void valueChanged(javax.swing.event.ListSelectionEvent e) 
    { 
     double[][] daRun = new double[2][7]; 

     final double dScoreUsed = 5; 
     double dMinScoreRun1 = 10, dMaxScoreRun1 = 0; 
     double dMinScoreRun2 = 10, dMaxScoreRun2 = 0; 

     double dTotalRun1 = 0, dTotalRun2 = 0; 

     jLabel_Athlete.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).sName); 
     jLabel_Country.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).sCountry); 

     jLabel_Run1_Score_1.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[0]); 
    jLabel_Run1_Score_2.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[1]); 
    jLabel_Run1_Score_3.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[2]); 
    jLabel_Run1_Score_4.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[3]); 
    jLabel_Run1_Score_5.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[4]); 
    jLabel_Run1_Score_6.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[5]); 
    jLabel_Run1_Score_7.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun1[6]); 

    jLabel_Run2_Score_1.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[0]); 
    jLabel_Run2_Score_2.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[1]); 
    jLabel_Run2_Score_3.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[2]); 
    jLabel_Run2_Score_4.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[3]); 
    jLabel_Run2_Score_5.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[4]); 
    jLabel_Run2_Score_6.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[5]); 
    jLabel_Run2_Score_7.setText(vecAthlete.get(jList_Athlete.getSelectedIndex()).saTempRun2[6]); 


    daRun[0][0] = Double.parseDouble(jLabel_Run1_Score_1.getText()); 
    daRun[0][1] = Double.parseDouble(jLabel_Run1_Score_2.getText()); 
    daRun[0][2] = Double.parseDouble(jLabel_Run1_Score_3.getText()); 
    daRun[0][3] = Double.parseDouble(jLabel_Run1_Score_4.getText()); 
    daRun[0][4] = Double.parseDouble(jLabel_Run1_Score_5.getText()); 
    daRun[0][5] = Double.parseDouble(jLabel_Run1_Score_6.getText()); 
    daRun[0][6] = Double.parseDouble(jLabel_Run1_Score_7.getText()); 

    daRun[1][0] = Double.parseDouble(jLabel_Run2_Score_1.getText()); 
    daRun[1][1] = Double.parseDouble(jLabel_Run2_Score_2.getText()); 
    daRun[1][2] = Double.parseDouble(jLabel_Run2_Score_3.getText()); 
    daRun[1][3] = Double.parseDouble(jLabel_Run2_Score_4.getText()); 
    daRun[1][4] = Double.parseDouble(jLabel_Run2_Score_5.getText()); 
    daRun[1][5] = Double.parseDouble(jLabel_Run2_Score_6.getText()); 
    daRun[1][6] = Double.parseDouble(jLabel_Run2_Score_7.getText()); 

    for(int i = 0; i < 7; i++) 
    { 
     if(daRun[0][i] <= dMinScoreRun1) 
     { 
      dMinScoreRun1 = daRun[0][i]; 
     } 
     if(daRun[0][i] >= dMaxScoreRun1) 
     { 
      dMaxScoreRun1 = daRun[0][i]; 
     } 

     dTotalRun1 += daRun[0][i]; 
    } 

    dTotalRun1 = (dTotalRun1 - dMinScoreRun1 - dMaxScoreRun1)/dScoreUsed; 
    jLabel_TotalRun1.setText(String.valueOf(dTotalRun1)); 
    jLabel_Run1AddInfo.setText("Min Score: " + (dMinScoreRun1) + ", Max Score: " + (dMaxScoreRun1)); 

    for(int i = 0; i < 7; i++) 
    { 
     if(daRun[1][i] <= dMinScoreRun2) 
     { 
      dMinScoreRun2 = daRun[1][i]; 
     } 
     if(daRun[1][i] >= dMaxScoreRun2) 
     { 
      dMaxScoreRun2 = daRun[1][i]; 
     } 

     dTotalRun2 += daRun[1][i]; 
    } 

    dTotalRun2 = (dTotalRun2 - dMinScoreRun2 - dMaxScoreRun2)/dScoreUsed; 
    jLabel_TotalRun2.setText(String.valueOf(dTotalRun2)); 
    jLabel_Run2AddInfo.setText("Min Score: " + (dMinScoreRun2) + ", Max Score: " + (dMaxScoreRun2)); 

    if(dTotalRun1 >= dTotalRun2) 
     jLabel_FinalScore.setText(String.valueOf(dTotalRun1)); 
    else 
     jLabel_FinalScore.setText(String.valueOf(dTotalRun2)); 


    jPanel_Graph.repaint(); 
} 
});

的JPanel定义

JPanel jPanel_Graph = new JPanel(); 
jPanel_Graph.setBorder(new BevelBorder(BevelBorder.LOWERED, null, null, null, null)); 
jPanel_Graph.setBounds(729, 159, 700, 200); 
frame.getContentPane().add(jPanel_Graph); 

img = new BufferedImage(jPanel_Graph.getWidth(), 
         jPanel_Graph.getHeight(), 
         BufferedImage.TYPE_INT_RGB); 

g2dimg = (Graphics2D)img.getGraphics(); 

// Draw a filled white coloured rectangle on the entire area to clear it. 
g2dimg.setPaint(Color.WHITE); 
g2dimg.fill(new Rectangle2D.Double(0, 0, img.getWidth(), img.getHeight()));

JPanel的描绘事件

class myJPanel extends JPanel 
{ 
private Rectangle2D.Double rectangle; 

public void paintComponent(Graphics g) 
{ 
    super.paintComponent(g); 

    for(int i = 0; i < 7; i++) 
    { 
     dHeight = daRun[0][i]; 

     rectangle = new Rectangle2D.Double(dX, dY, dWidth, dHeight); 
     g2dimg.setPaint(Color.red); 
     g2dimg.draw(rectangle); 
     g2dimg.fill(rectangle); 

     dX += dXIncrement; 
     g2dimg.drawImage(img, 0, 0, null); 
     } 
    } 
}

提前致谢！

我真的不知道怎么说都应该拼凑数据或者事实上，如果是的话，它实际上会起作用。 “jPanel_Graph”如何知道它应该画什么？ – MadProgrammer

考虑一下，'JPanel'（它永远是它）负责渲染模型，你的'ListSelectionListener'负责生成该模型并将其传递给'JPanel'，以便它可以呈现结果 – MadProgrammer

好吧，考虑到这一点，我如何将这些信息真正传递给JPanel以在结果中呈现？ –

答

所以，从我所知道的情况来看，你的“图表”无法知道它应该画什么。基本思想是，你的“图表”应该专注于绘制数据/模型，所以你需要一些方法来告诉它数据的变化。

有很多方法可以做到这一点，例如，您可以设计一个模型，您可以添加/删除数据，这可能会触发图窗格侦听器的更新，然后使用新数据更新自身。

，或者你只是通过你要直接更新到图形窗格中，在这种情况下，可能最简单的解决方案提供给您

import java.awt.BorderLayout; 
import java.awt.Color; 
import java.awt.Dimension; 
import java.awt.EventQueue; 
import java.awt.Graphics; 
import java.awt.Graphics2D; 
import java.awt.geom.Rectangle2D; 
import javax.swing.DefaultListModel; 
import javax.swing.JFrame; 
import javax.swing.JList; 
import javax.swing.JPanel; 
import javax.swing.JScrollPane; 
import javax.swing.UIManager; 
import javax.swing.UnsupportedLookAndFeelException; 
import javax.swing.event.ListSelectionEvent; 
import javax.swing.event.ListSelectionListener; 

public class Test { 

    public static void main(String[] args) { 
     new Test(); 
    } 

    public Test() { 
     EventQueue.invokeLater(new Runnable() { 
      @Override 
      public void run() { 
       try { 
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName()); 
       } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) { 
        ex.printStackTrace(); 
       } 

       JFrame frame = new JFrame("Testing"); 
       frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
       frame.add(new TestPane()); 
       frame.pack(); 
       frame.setLocationRelativeTo(null); 
       frame.setVisible(true); 
      } 
     }); 
    } 

    public class TestPane extends JPanel { 

     private GraphPane graphPane; 

     public TestPane() { 
      setLayout(new BorderLayout()); 
      DefaultListModel<Double> listmodel = new DefaultListModel<>(); 
      for (int index = 0; index < 100; index++) { 
       listmodel.addElement(Math.random()); 
      } 

      graphPane = new GraphPane(); 
      add(graphPane); 

      JList<Double> listData = new JList<>(listmodel); 
      add(new JScrollPane(listData), BorderLayout.WEST); 

      listData.addListSelectionListener(new ListSelectionListener() { 
       @Override 
       public void valueChanged(ListSelectionEvent e) { 
        graphPane.setData(listData.getSelectedValuesList().toArray(new Double[0])); 
       } 
      }); 
     } 

    } 

    public class GraphPane extends JPanel { 

     private Double[] data; 

     public void setData(Double[] data) { 
      this.data = data; 
      repaint(); 
     } 

     @Override 
     public Dimension getPreferredSize() { 
      return new Dimension(200, 200); 
     } 

     @Override 
     protected void paintComponent(Graphics g) { 
      super.paintComponent(g); 
      if (data != null && data.length > 0) { 
       Graphics2D g2d = (Graphics2D) g.create(); 
       double barWidth = getWidth()/(double)data.length; 
       int xPos = 0; 
       for (Double value : data) { 
        double height = (getHeight() - 1) * value; 
        Rectangle2D bar = new Rectangle2D.Double(xPos, getHeight() - height, barWidth, height); 
        g2d.setColor(Color.GREEN); 
        g2d.fill(bar); 
        g2d.setColor(Color.BLACK); 
        g2d.draw(bar); 
        xPos += barWidth; 
       } 
       g2d.dispose(); 
      } 
     } 

    } 

}

如何从JList选项中绘制矩形

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