JComboBox无法在JTable TableHeader中展开 [英] JComboBox fails to expand in JTable TableHeader

问题描述

我已经阅读了大多数有关此类问题的JTable/JComboBox答复，但尚未找到解决我问题的方法.

I have read through the majority of the JTable/JComboBox responses to other questions of this ilk, but haven't yet found a solution to my problem.

我创建了一个包含JComboBox TableHeader元素的表. JComboBox元素均不会打开以显示项目列表.如何获取要显示的单个JComboBox元素的项目列表?

I have created a table that has JComboBox TableHeader elements. None of the JComboBox elements will open to display a list of items. How do I get the item lists for the individual JComboBox elements to display?

请注意，此问题的一个区别元素是JComboBox位于TableHeader中，而不是嵌入在JTable单元中.

Please note that a distinguishing element of this question is that the JComboBox is in the TableHeader, not embedded within a JTable cell.

感谢您的帮助.

SSCE

import java.awt.Component;
import java.awt.Dimension;
import java.util.Enumeration;

import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.ListSelectionModel;
import javax.swing.SwingUtilities;
import javax.swing.table.TableCellRenderer;
import javax.swing.table.TableColumn;

public class ComboHeaderTest extends JScrollPane {

private static final Dimension DEFAULT_SIZE = new Dimension(200, 200);

public static void main(String[] args) {
    SwingUtilities.invokeLater(new Runnable() {

        @Override
        public void run() {
            new ComboHeaderTest().initComponents();
        }
    });
}

private ComboHeaderTest() {

    final String[][] data = { {"Header 1", "Header 2", "Header 3"},
                                {"A", "B", "C"},
                                {"D", "E", "F"},
                                {"G", "H", "I"}};

    setViewportView(getTable(data));
    setPreferredSize(DEFAULT_SIZE);
}

private void initComponents() {

    JFrame frame = new JFrame("ComboHeaderTest");
    frame.add(this);
    frame.pack();
    frame.setVisible(true);
}

private JTable getTable(final String[][] data) {
    final String[] items = data[0];

    final ComboHeaderRenderer[] columnHeaders = new ComboHeaderRenderer[items.length];
    for(int i = 0; items.length > i; ++i) {
        columnHeaders[i] = new ComboHeaderRenderer(items);
    }

    final JTable table = new JTable(data, columnHeaders);

    final Enumeration<TableColumn> tableEnum = table.getColumnModel().getColumns();
    for (int columnIndex = 0; tableEnum.hasMoreElements(); ++columnIndex) {
        final TableColumn column = tableEnum.nextElement();

        final ComboHeaderRenderer combo = columnHeaders[columnIndex];
        column.setHeaderValue(combo.getItemAt(columnIndex));
        column.setHeaderRenderer(combo);
    }

    table.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    table.setRowSelectionAllowed(true);
    table.setColumnSelectionAllowed(false);
    table.setCellSelectionEnabled(false);
    table.setFillsViewportHeight(true);

    table.setSize(DEFAULT_SIZE);
    table.validate();

    return table;
}

private static class ComboHeaderRenderer extends JComboBox implements TableCellRenderer{
    public ComboHeaderRenderer(final String[] entries) {
        for (int i = 0; entries.length > i; ++i) {
            addItem(entries[i]);
        }
    }

    @Override
    public Component getTableCellRendererComponent(final JTable table, final Object value,
            final boolean isSelected, final boolean hasFocus, final int row, final int column) {
        setSelectedItem(value);
        return this;
    }
}
}

推荐答案

这实际上完全符合预期.我认为线索是TableCellRenderer.

This actually works exactly as expected. I think the clue is TableCellRenderer.

渲染器通常是非交互组件.它们通常只是涂在表面上的组件的快照"，用户通常无法与它们进行交互.

Renderer's are typically non-interactive components. They are usually just a "snap-shot" of the component painted on to a surface and there is typically no way for a user to interact with them.

这是预期的行为.

为了向表头提供可编辑的功能，您将需要提供JTableHeader

In order to supply editable functionality to the table header, you're going to need to supply your implementation of a JTableHeader

请参阅以下示例以获得一些想法

Have a look at this example for some ideas

这篇关于JComboBox无法在JTable TableHeader中展开的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！