我正在寻找关于我正在编写的Java程序的一些帮助。我需要显示一个简单的条形图，该条形图由基于保存在由JList选择事件生成的数组中的数据的矩形组成。但是，JPanel中没有绘制任何内容，我无法弄清楚如何修复它。
列表选择事件（供参考）
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();
}
});
JPanel Definitions
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绘图活动
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！
答案 0 :(得分：1)
所以，从我所知道的，你的“图表”无法知道它应该画什么。基本的想法是，你的“图形”应该专注于绘制数据/模型，所以你需要一些方法来告诉它何时数据发生变化。
有很多方法可以做到这一点，例如，你可以设计一个模型，你可以添加/删除数据，这可以触发图形窗格监听器的更新，然后用新数据更新自己。 / p>
或者您只需将要更新的数据直接传递到图表窗格，在这种情况下，您可以使用最简单的解决方案
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();
}
}
}
}