问题
I'm working on a code in Java Swing. I have created a JComboBox in JTable. It's working :). But once I select a value and click on the save or cancel button, it has to reset to the default value (1st value in the combo box). I tried a lot of ways like combobox.setSelectedIndex(0). This isn't working.
Code:
String[] manTimeHr = { "00","01", "02", "03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23"};
String[] manTimeMin = {"00","01", "02", "03","04","05","06","07","08","09","10","11","12","13", "14", "15","16","17","18","19","20","21","22","23","24","25", "26", "27","28","29","30","31","32","33","34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50","51","52","53","54","55","56","57","58","59"};
String[][] data = {{"-select-","-select-"}};
String[] cols = {"Hrs","Mins"};
String[][] data1 = {{"-select-","-select-"}};
String[] cols1 = {"Hrs","Mins"};
JLabel manTimeStart = new JLabel("Start From",JLabel.LEFT);
STimeTbl = new JTable(data,cols);
hrsColumn=STimeTbl.getColumnModel().getColumn(0);
minsColumn=STimeTbl.getColumnModel().getColumn(1);
manSiteStimeHrCBx = new JComboBox(manTimeHr);
manSiteStimeHrCBx.setSelectedIndex(0);
hrsColumn.setCellEditor(new DefaultCellEditor(manSiteStimeHrCBx));
manSiteStimeMinCBx = new JComboBox(manTimeMin);
manSiteStimeMinCBx.setSelectedIndex(0);
minsColumn.setCellEditor(new DefaultCellEditor(manSiteStimeMinCBx));
JLabel manTimeEnd = new JLabel("End To",JLabel.LEFT);
ETimeTbl = new JTable(data1,cols1);
hrsColumn1=ETimeTbl.getColumnModel().getColumn(0);
minsColumn1=ETimeTbl.getColumnModel().getColumn(1);
manSiteEtimeHrCBx = new JComboBox(manTimeHr);
manSiteEtimeHrCBx.setSelectedIndex(0);
hrsColumn1.setCellEditor(new DefaultCellEditor(manSiteEtimeHrCBx));
manSiteEtimeMinCBx = new JComboBox(manTimeMin);
manSiteEtimeMinCBx.setSelectedIndex(0);
minsColumn1.setCellEditor(new DefaultCellEditor(manSiteEtimeMinCBx));
.
.
.
.
if("Save".equals(e.getActionCommand())) {
try{
mSHr = Integer.parseInt((String)manSiteStimeHrCBx.getSelectedItem());
mEHr=Integer.parseInt((String)manSiteEtimeHrCBx.getSelectedItem());
mSMin=Integer.parseInt((String)manSiteStimeMinCBx.getSelectedItem());
mEMin=Integer.parseInt((String)manServEtimeMinCBx.getSelectedItem());
}catch (Exception en){
System.out.println("Main Exception : "+ en);
return;
}
if(validateBlockTime(mSHr,mEHr,mSMin,mEMin) != true)
{
System.out.println("Enter valid Time");
return;
}
manSiteStimeHrCBx.setSelectedIndex(0);
manSiteStimeMinCBx.setSelectedIndex(0);
manSiteEtimeHrCBx.setSelectedIndex(0);
manSiteEtimeMinCBx.setSelectedIndex(0);
.
.
.
private static boolean validateBlockTime(int val3, int val4, int val5, int val6){
if(val4 > val3)
return true;
else if((val4 == val3) && (val6 > val5))
return true;
else
return false;
}
回答1:
JTable tutorial contains description about Combo Box as an Editor
all data are stored in the XxxTableModel
all changes in the JTable view are described in Concepts: Editors and Renderers
then you have to know that in the XxxTableModel is stored only String value (or
DoubleorLongorIntegerorIcon, depends of value stored in ComboBoxModel) for Combo Box as an Editorresult is
quick code (sorry I'm so lazy) based on tutorial code
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import javax.swing.DefaultCellEditor;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.table.AbstractTableModel;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.ActionListener;
import javax.swing.JButton;
public class TableRenderDemo extends JPanel {
private static final long serialVersionUID = 1L;
private boolean DEBUG = false;
public TableRenderDemo() {
super(new BorderLayout(5, 5));
final JTable table = new JTable(new MyTableModel());
table.setRowHeight(18);
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
table.setFillsViewportHeight(true);
table.setPreferredScrollableViewportSize(table.getPreferredSize());
JScrollPane scrollPane = new JScrollPane(table);
initColumnSizes(table);
setUpSportColumn(table, table.getColumnModel().getColumn(2));
add(scrollPane);
JButton resetButton = new JButton("Reset to default");
resetButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
for (int i = 0; i < table.getRowCount(); i++) {
table.getModel().setValueAt("None of the above", i, 2);
}
}
});
add(resetButton, BorderLayout.SOUTH);
}
private void initColumnSizes(JTable table) {
MyTableModel model = (MyTableModel) table.getModel();
TableColumn column = null;
Component comp = null;
int headerWidth = 0;
int cellWidth = 0;
Object[] longValues = model.longValues;
TableCellRenderer headerRenderer = table.getTableHeader().getDefaultRenderer();
for (int i = 0; i < 5; i++) {
column = table.getColumnModel().getColumn(i);
comp = headerRenderer.getTableCellRendererComponent(null, column.getHeaderValue(), false, false, 0, 0);
headerWidth = comp.getPreferredSize().width;
comp = table.getDefaultRenderer(model.getColumnClass(i)).getTableCellRendererComponent(table, longValues[i], false, false, 0, i);
cellWidth = comp.getPreferredSize().width;
if (DEBUG) {
System.out.println("Initializing width of column " + i + ". " + "headerWidth = " + headerWidth + "; cellWidth = " + cellWidth);
}
column.setPreferredWidth(Math.max(headerWidth, cellWidth));
}
}
private void setUpSportColumn(JTable table, TableColumn sportColumn) {
JComboBox comboBox = new JComboBox();
comboBox.addItem("Snowboarding");
comboBox.addItem("Rowing");
comboBox.addItem("Knitting");
comboBox.addItem("Speed reading");
comboBox.addItem("Pool");
comboBox.addItem("None of the above");
sportColumn.setCellEditor(new DefaultCellEditor(comboBox));
DefaultTableCellRenderer renderer = new DefaultTableCellRenderer();
renderer.setToolTipText("Click for combo box");
sportColumn.setCellRenderer(renderer);
}
private class MyTableModel extends AbstractTableModel {
private static final long serialVersionUID = 1L;
private String[] columnNames = {"First Name", "Last Name", "Sport", "# of Years", "Vegetarian"};
private Object[][] data = {
{"Kathy", "Smith", "Snowboarding", new Integer(5), false},
{"John", "Doe", "Rowing", new Integer(3), true},
{"Sue", "Black", "Knitting", new Integer(2), false},
{"Jane", "White", "Speed reading", new Integer(20), true},
{"Joe", "Brown", "Pool", new Integer(10), false}
};
public final Object[] longValues = {"Jane", "Kathy", "None of the above", new Integer(20), Boolean.TRUE};
public int getColumnCount() {
return columnNames.length;
}
public int getRowCount() {
return data.length;
}
@Override
public String getColumnName(int col) {
return columnNames[col];
}
public Object getValueAt(int row, int col) {
return data[row][col];
}
@Override
public Class<?> getColumnClass(int c) {
return getValueAt(0, c).getClass();
}
@Override
public boolean isCellEditable(int row, int col) {
if (col < 2) {
return false;
} else {
return true;
}
}
@Override
public void setValueAt(Object value, int row, int col) {
data[row][col] = value;
fireTableCellUpdated(row, col);
System.out.println(getValueAt(row, col));
}
}
private static void createAndShowGUI() {
JFrame frame = new JFrame("TableRenderDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TableRenderDemo newContentPane = new TableRenderDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
output from AbstractTableModel, code line 135th.
run:
None of the above
None of the above
None of the above
None of the above
None of the above
BUILD SUCCESSFUL (total time: 37 seconds)
来源：https://stackoverflow.com/questions/12297459/how-to-reset-the-jcombobox-in-jtable-to-the-first-value-of-the-jcombobox