我试图了解如何将JComboBox放入JTable中，因此我使用了JTable教程中的演示。
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.GridLayout;
/**
* TableRenderDemo is just like TableDemo, except that it
* explicitly initializes column sizes and it uses a combo box
* as an editor for the Sport column.
*/
public class TableRenderDemo extends JPanel {
private boolean DEBUG = false;
public TableRenderDemo() {
super(new GridLayout(1,0));
JTable table = new JTable(new MyTableModel());
table.setPreferredScrollableViewportSize(new Dimension(500, 70));
table.setFillsViewportHeight(true);
//Create the scroll pane and add the table to it.
JScrollPane scrollPane = new JScrollPane(table);
//Set up column sizes.
initColumnSizes(table);
//Fiddle with the Sport column's cell editors/renderers.
setUpSportColumn(table, table.getColumnModel().getColumn(2));
//Add the scroll pane to this panel.
add(scrollPane);
}
/*
* This method picks good column sizes.
* If all column heads are wider than the column's cells'
* contents, then you can just use column.sizeWidthToFit().
*/
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));
}
}
public void setUpSportColumn(JTable table,
TableColumn sportColumn) {
//Set up the editor for the sport cells.
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));
//Set up tool tips for the sport cells.
DefaultTableCellRenderer renderer =
new DefaultTableCellRenderer();
renderer.setToolTipText("Click for combo box");
sportColumn.setCellRenderer(renderer);
}
class MyTableModel extends AbstractTableModel {
private String[] columnNames = {"First Name",
"Last Name",
"Sport",
"# of Years",
"Vegetarian"};
private Object[][] data = {
{"Kathy", "Smith",
"Snowboarding", new Integer(5), new Boolean(false)},
{"John", "Doe",
"Rowing", new Integer(3), new Boolean(true)},
{"Sue", "Black",
"Knitting", new Integer(2), new Boolean(false)},
{"Jane", "White",
"Speed reading", new Integer(20), new Boolean(true)},
{"Joe", "Brown",
"Pool", new Integer(10), new Boolean(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;
}
public String getColumnName(int col) {
return columnNames[col];
}
public Object getValueAt(int row, int col) {
return data[row][col];
}
/*
* JTable uses this method to determine the default renderer/
* editor for each cell. If we didn't implement this method,
* then the last column would contain text ("true"/"false"),
* rather than a check box.
*/
public Class getColumnClass(int c) {
return getValueAt(0, c).getClass();
}
/*
* Don't need to implement this method unless your table's
* editable.
*/
public boolean isCellEditable(int row, int col) {
//Note that the data/cell address is constant,
//no matter where the cell appears onscreen.
if (col < 2) {
return false;
} else {
return true;
}
}
/*
* Don't need to implement this method unless your table's
* data can change.
*/
public void setValueAt(Object value, int row, int col) {
if (DEBUG) {
System.out.println("Setting value at " + row + "," + col
+ " to " + value
+ " (an instance of "
+ value.getClass() + ")");
}
data[row][col] = value;
fireTableCellUpdated(row, col);
if (DEBUG) {
System.out.println("New value of data:");
printDebugData();
}
}
private void printDebugData() {
int numRows = getRowCount();
int numCols = getColumnCount();
for (int i=0; i < numRows; i++) {
System.out.print(" row " + i + ":");
for (int j=0; j < numCols; j++) {
System.out.print(" " + data[i][j]);
}
System.out.println();
}
System.out.println("--------------------------");
}
}
/**
* Create the GUI and show it. For thread safety,
* this method should be invoked from the
* event-dispatching thread.
*/
private static void createAndShowGUI() {
//Create and set up the window.
JFrame frame = new JFrame("TableRenderDemo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
//Create and set up the content pane.
TableRenderDemo newContentPane = new TableRenderDemo();
newContentPane.setOpaque(true); //content panes must be opaque
frame.setContentPane(newContentPane);
//Display the window.
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
//Schedule a job for the event-dispatching thread:
//creating and showing this application's GUI.
javax.swing.SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGUI();
}
});
}
}
通常情况下，JComboBox在点击之前不会显示。我想让它一直显示，以便用户知道该列中有一个组合框。我试过自定义渲染器（在这个论坛上找到了一些）来解决这个问题，但遇到的问题让我走上了一条错误的道路。是否有某个示例显示如何在不先单击的情况下显示组合框。 TIA。
答案 0 :(得分：1)
渲染器看起来像：
class ComboBoxRenderer extends JComboBox implements TableCellRenderer
{
public ComboBoxRenderer()
{
setBorder(null);
}
public Component getTableCellRendererComponent(
JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
{
removeAllItems();
addItem( value );
return this;
}
}
答案 1 :(得分：0)
您可以使用以下代码在第一次单击时调用Combobox编辑器。
library(tidyr)
library(dplyr)
library(tibble)
long_data = data.frame(X1=c("A", "B", "C", "D"), X2=c("a", "b", "c", "d"))
long_data %>%
spread(X1, 1) %>%
mutate_at(vars(-X2), funs(if_else(is.na(.), 0, 1))) %>%
column_to_rownames("X2") %>%
write.table(file="TestData.csv", quote=F, sep=";")
# A;B;C;D
# a;1;0;0;0
# b:0;1;0;0
# c;0;0;1;0
# d;0;0;0;1
expand.grid(long_data) %>%
left_join(long_data %>% mutate(val=1)) %>%
replace_na(list(val=0)) %>%
write.table(file="TestData2.csv", quote=F, sep=";")
# X1;X2;val
# A;a;1
# B;a;0
# C;a;0
# D;a;0
# A;b;0
# B;b;1
# C;b;0
# D;b;0
# A;c;0
# B;c;0
# C;c;1
# D;c;0
# A;d;0
# B;d;0
# C;d;0
# D;d;1