我正在通过 Java 查询 MySQL 数据库，从结果集中提取数据并将其放入 DefaultTableModel 中，该模型放入 JTable 中，然后放入 JScrollPane 中进行显示。
在 JTable 中，我通过
在表中启用排序table.setAutoCreateRowSorter(true);
但是，如果我想要排序的行中的单元格不属于 String 类，那么我会得到 java.lang.ClassCastException。我的表中的数据有以下类别:
java.sql.Date
java.sql.Time
java.lang.Double
java.lang.Boolean
java.lang.String
下面是当我尝试对类 java.lang.Double 的列进行排序时出现的错误，后跟将结果集作为输入输出 JTable 的类。如果有人对我如何解决排序问题有任何想法，我将不胜感激。
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: java.lang.Double `enter code here`cannot be cast to java.lang.String
at java.text.Collator.compare(Collator.java:327)
at javax.swing.DefaultRowSorter.compare(DefaultRowSorter.java:968)
at javax.swing.DefaultRowSorter.access$100(DefaultRowSorter.java:112)
at javax.swing.DefaultRowSorter$Row.compareTo(DefaultRowSorter.java:1376)
at javax.swing.DefaultRowSorter$Row.compareTo(DefaultRowSorter.java:1366)
at java.util.ComparableTimSort.countRunAndMakeAscending(ComparableTimSort.java:290)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:157)
at java.util.ComparableTimSort.sort(ComparableTimSort.java:146)
at java.util.Arrays.sort(Arrays.java:472)
at javax.swing.DefaultRowSorter.sort(DefaultRowSorter.java:607)
at javax.swing.DefaultRowSorter.setSortKeys(DefaultRowSorter.java:319)
at javax.swing.DefaultRowSorter.toggleSortOrder(DefaultRowSorter.java:480)
at javax.swing.plaf.basic.BasicTableHeaderUI$MouseInputHandler.mouseClicked(BasicTableHeaderUI.java:112)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
at java.awt.Component.processMouseEvent(Component.java:6508)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
at java.awt.Component.processEvent(Component.java:6270)
at java.awt.Container.processEvent(Container.java:2229)
at java.awt.Component.dispatchEventImpl(Component.java:4861)
at java.awt.Container.dispatchEventImpl(Container.java:2287)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4501)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
at java.awt.Container.dispatchEventImpl(Container.java:2273)
at java.awt.Window.dispatchEventImpl(Window.java:2713)
at java.awt.Component.dispatchEvent(Component.java:4687)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
at java.awt.EventQueue.access$000(EventQueue.java:101)
at java.awt.EventQueue$3.run(EventQueue.java:666)
at java.awt.EventQueue$3.run(EventQueue.java:664)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
at java.awt.EventQueue$4.run(EventQueue.java:680)
at java.awt.EventQueue$4.run(EventQueue.java:678)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
这是该类的源代码:
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.Vector;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JFrame;
import javax.swing.JTable;
import javax.swing.JToggleButton;
import javax.swing.UIManager;
import javax.swing.event.TableModelEvent;
import javax.swing.event.TableModelListener;
import javax.swing.table.*;
public class ResultSetToCheckBoxTable {
private int numberOfColumns;
private DefaultTableModel model;
private ResultSetMetaData metaData;
private JTable table;
private ResultSet rs;
private TableColumn tc;
public JTable getTable() {
return table;
}
public ResultSetToCheckBoxTable(ResultSet rs) {
try {
this.rs = rs;
//overrides getColumnClass method in DefaultTableModel to help make checkbox
model = new DefaultTableModel() {
@Override
public Class<?> getColumnClass(int columnIndex) {
if (columnIndex == numberOfColumns) {
return Boolean.class;
} else {
//return getValueAt(0, columnIndex).getClass();
return String.class;
}
}
};
// Get the column names
metaData = this.rs.getMetaData();
numberOfColumns = metaData.getColumnCount();
for (int column = 1; column <= numberOfColumns; column++) {
model.addColumn(metaData.getColumnLabel(column));
}
model.addColumn("");
// Get the table info
while (rs.next()) {
Vector tableRow = new Vector();
for (int i = 1; i <= numberOfColumns; i++) {
tableRow.addElement(rs.getObject(i));
}
tableRow.addElement(true);
model.addRow(tableRow);
}
//Create JTable using the model & set options
table = new JTable(model) {
@Override
public boolean isCellEditable(int row, int column) {
return false;
};
};
table.setAutoCreateRowSorter(true);
table.setPreferredScrollableViewportSize(new Dimension(320, 160));
//Rest of the stuff
tc = table.getColumnModel().getColumn(numberOfColumns);
tc.setHeaderRenderer(new SelectAllHeader(table, numberOfColumns));
}
catch (SQLException ex) {
Logger.getLogger(ResultSetToCheckBoxTable.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args) {
}
}
/**
* A TableCellRenderer that selects all or none of a Boolean column.
*
* @param numberOfColumns the Boolean column to manage
*/
class SelectAllHeader extends JToggleButton implements TableCellRenderer {
private static final String ALL = "✓ Select all";
private static final String NONE = "✓ Select none";
private JTable table;
private TableModel tableModel;
private JTableHeader header;
private TableColumnModel tcm;
private int targetColumn;
private int viewColumn;
public SelectAllHeader(JTable table, int targetColumn) {
super(ALL);
this.table = table;
this.tableModel = table.getModel();
if (tableModel.getColumnClass(targetColumn) != Boolean.class) {
throw new IllegalArgumentException("Boolean column required.");
}
this.targetColumn = targetColumn;
this.header = table.getTableHeader();
this.tcm = table.getColumnModel();
this.applyUI();
this.addItemListener(new ItemHandler());
header.addMouseListener(new MouseHandler());
tableModel.addTableModelListener(new ModelHandler());
}
@Override
public Component getTableCellRendererComponent(
JTable table, Object value, boolean isSelected,
boolean hasFocus, int row, int column) {
return this;
}
private class ItemHandler implements ItemListener {
@Override
public void itemStateChanged(ItemEvent e) {
boolean state = e.getStateChange() == ItemEvent.SELECTED;
setText((state) ? NONE : ALL);
for (int r = 0; r < table.getRowCount(); r++) {
table.setValueAt(state, r, viewColumn);
}
}
}
@Override
public void updateUI() {
super.updateUI();
applyUI();
}
private void applyUI() {
this.setFont(UIManager.getFont("TableHeader.font"));
this.setBorder(UIManager.getBorder("TableHeader.cellBorder"));
this.setBackground(UIManager.getColor("TableHeader.background"));
this.setForeground(UIManager.getColor("TableHeader.foreground"));
}
private class MouseHandler extends MouseAdapter {
@Override
public void mouseClicked(MouseEvent e) {
viewColumn = header.columnAtPoint(e.getPoint());
int modelColumn = tcm.getColumn(viewColumn).getModelIndex();
if (modelColumn == targetColumn) {
doClick();
}
}
}
private class ModelHandler implements TableModelListener {
@Override
public void tableChanged(TableModelEvent e) {
if (needsToggle()) {
doClick();
header.repaint();
}
}
}
// Return true if this toggle needs to match the model.
private boolean needsToggle() {
boolean allTrue = true;
boolean allFalse = true;
for (int r = 0; r < tableModel.getRowCount(); r++) {
boolean b = (Boolean) tableModel.getValueAt(r, targetColumn);
allTrue &= b;
allFalse &= !b;
}
return allTrue && !isSelected() || allFalse && isSelected();
}
}
最佳答案
问题是您告诉 JTable 您的所有列都包含字符串(除了最后一个列)，这是不正确的:
public Class<?> getColumnClass(int columnIndex) {
if (columnIndex == numberOfColumns) {
return Boolean.class;
} else {
//return getValueAt(0, columnIndex).getClass();
return String.class;
}
}
对 JTable 说实话，它会很高兴。
关于java - 在 JTable 中使用 setAutoCreateRowSorter 对不同数据类型进行排序，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10565262/