Question

TL：DR我想创建一个JComboBox，其中JCheckboxes代替JLabels，但在主标签中 - 在这个地方我想保留字符串代表所有选中的值框。我设法让它工作，但是我在点击鼠标时保持菜单打开时遇到了一些麻烦。我还希望箭头键只是在框中导航而不选择要选择的项目和空格键。

无论我做什么，在我的ActionListener捕获鼠标并选择一个项目之后，菜单通过嵌套在JComboBox和方法setPopupVisible中的其他一些监听器关闭 - 它适用于我的丑陋的解决方法，但必须有一个更好的方法来做到这一点..

我相信我需要listBox课程BasicComboBoxUI上的小鼠听众，但我该如何到达那里？

尽可能少的代码缩小到：

ComboCheckBoxModel：

import javax.swing.*;
import java.awt.*;
import java.awt.event.ItemListener;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class ComboCheckBoxModel extends DefaultListModel implements ComboBoxModel, ItemSelectable {


    private List<String> items = new ArrayList<>();
    private List<String> checkedItems = new ArrayList<>();
    private String selectedItem;

    public ComboCheckBoxModel(List<String> items) {
        if(!items.isEmpty()) {
            selectedItem = items.get(0);
        }
        this.items = items;
    }

    public void check(Object item) {
        String itemAsString = item.toString();
        if(checkedItems.contains(itemAsString)) {
            checkedItems.remove(itemAsString);
        } else {
            checkedItems.add(itemAsString);
        }
        fireContentsChanged(this, items.indexOf(item), items.indexOf(item));
    }

    public String getDataStringRepresentation() {
        return checkedItems.stream().sorted().collect(Collectors.joining(", "));
    }

    @Override
    public void setSelectedItem(Object anItem) {
        selectedItem = anItem.toString();
    }

    @Override
    public Object getSelectedItem() {
        return selectedItem;
    }

    @Override
    public int getSize() {
        return items.size();
    }

    @Override
    public Object getElementAt(int index) {
        return items.get(index);
    }

    public boolean isChecked(String stringValue) {
        return checkedItems.contains(stringValue);
    }

    @Override
    public Object[] getSelectedObjects() {
        return items.toArray();
    }

    @Override
    public void addItemListener(ItemListener l) {

    }

    @Override
    public void removeItemListener(ItemListener l) {

    }
}

的JComboBox：

import javax.swing.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.InputEvent;
import java.awt.event.KeyEvent;
import java.util.stream.Stream;

import static java.util.stream.Collectors.toList;

public class JComboCheckBox extends JComboBox {

    private final ComboCheckBoxModel model = new ComboCheckBoxModel(Stream.of("bum", "kabum", "dabum").collect(toList()));
    private boolean shouldntClose;

    public JComboCheckBox() {
        super();
        setRenderer(new CheckBoxCellRenderer());
        setModel(model);

        addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                if (e.getModifiers() == InputEvent.BUTTON1_MASK) {
                    System.out.println("LPM MASK");
                    model.check(model.getSelectedItem());
                    shouldntClose = true;
                }
            }
        });
    }

    @Override
    protected boolean processKeyBinding(KeyStroke ks, KeyEvent e, int condition, boolean pressed) {
        if (ks.getKeyCode() == KeyEvent.VK_SPACE && isPopupVisible()) {
            if (ks.getKeyCode() == KeyEvent.VK_SPACE && condition == WHEN_FOCUSED && ks.isOnKeyRelease()) {
                System.out.println("ks = [" + ks + "], e = [" + e + "], condition = [" + condition + "], pressed = [" + pressed + "]");
                model.check(model.getSelectedItem());
            }
            return true;
        }
        return super.processKeyBinding(ks, e, condition, pressed);
    }


    @Override
    public void setPopupVisible(boolean v) {
        if (shouldntClose) {
            shouldntClose = false;
            return;
        } else {
            super.setPopupVisible(v);
        }

    }

    @Override
    public Object getSelectedItem() {
        return model.getSelectedItem();
    }
}

细胞渲染器：

import javax.swing.*;
import java.awt.*;

public class CheckBoxCellRenderer extends JCheckBox implements ListCellRenderer {
    @Override
    public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {

        ComboCheckBoxModel model = (ComboCheckBoxModel) list.getModel();
        if (index != -1) {
            String stringValue = value == null ? "null" : value.toString();
            setText(stringValue);

            boolean checked = model.isChecked(stringValue);
            setSelected(checked);

            if (isSelected) {
                setBackground(list.getSelectionBackground());
                setForeground(list.getSelectionForeground());
            } else {
                setBackground(list.getBackground());
                setForeground(list.getForeground());
            }

            return this;
        } else {
            String stringValue = model.getDataStringRepresentation();
            return new JLabel(stringValue);
        }
    }
}

发射器：

import javax.swing.*;

public class Launcher {
    public JFrame create() {
        JFrame f=new JFrame("Type the name of frame");
        f.add(new JComboCheckBox());
        f.setSize(400,400);
        return f;
    }

    public static void main(String[] args) {
        Launcher launcher = new Launcher();
        launcher.create().setVisible(true);
    }
}

Answer 1

类BasicComboBoxUI中的listBox但是我如何到达那里？

listBox（JList？）可以从BasicComboPopup获取：

Accessible a = getAccessibleContext().getAccessibleChild(0);
if (a instanceof BasicComboPopup) {
  BasicComboPopup pop = (BasicComboPopup) a;
  int index = pop.getList().getSelectedIndex();
  //...
}

的 ComboCheckBoxTest.java

import java.awt.*; import java.awt.event.*; import java.util.*; import java.util.List; import java.util.stream.Collectors; import javax.accessibility.*; import javax.swing.*; import javax.swing.plaf.basic.*; public class ComboCheckBoxTest { public JComponent makeUI() { CheckableItem[] m = { new CheckableItem("bum", false), new CheckableItem("kabum", false), new CheckableItem("dabum", false) }; JPanel p = new JPanel(); p.add(new JComboCheckBox<CheckableItem>(m)); return p; } public static void main(String[] args) { EventQueue.invokeLater(() -> { JFrame f = new JFrame("Type the name of frame"); f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE); f.getContentPane().add(new ComboCheckBoxTest().makeUI()); f.setSize(320, 240); f.setLocationRelativeTo(null); f.setVisible(true); }); } } class CheckableItem { public final String text; public boolean selected; protected CheckableItem(String text, boolean selected) { this.text = text; this.selected = selected; } @Override public String toString() { return text; } } class CheckBoxCellRenderer<E extends CheckableItem> implements ListCellRenderer<E> { private final JLabel label = new JLabel(" "); private final JCheckBox check = new JCheckBox(" "); @Override public Component getListCellRendererComponent( JList list, CheckableItem value, int index, boolean isSelected, boolean cellHasFocus) { ListModel model = list.getModel(); if (index < 0) { label.setText(getDataStringRepresentation(model)); return label; } else { check.setText(Objects.toString(value, "null")); check.setSelected(value.selected); if (isSelected) { check.setBackground(list.getSelectionBackground()); check.setForeground(list.getSelectionForeground()); } else { check.setBackground(list.getBackground()); check.setForeground(list.getForeground()); } return check; } } private String getDataStringRepresentation(ListModel model) { List<String> sl = new ArrayList<>(); for (int i = 0; i < model.getSize(); i++) { Object o = model.getElementAt(i); if (o instanceof CheckableItem && ((CheckableItem) o).selected) { sl.add(o.toString()); } } return sl.stream().sorted().collect(Collectors.joining(", ")); } } class JComboCheckBox<E extends CheckableItem> extends JComboBox<E> { private boolean shouldntClose; private transient ActionListener listener; public JComboCheckBox() { super(); } public JComboCheckBox(E[] m) { super(m); } @Override public Dimension getPreferredSize() { return new Dimension(200, 20); } @Override public void updateUI() { setRenderer(null); removeActionListener(listener); super.updateUI(); listener = e -> { if (e.getModifiers() == InputEvent.BUTTON1_MASK) { System.out.println("LPM MASK: " + getSelectedIndex()); updateItem(getSelectedIndex()); shouldntClose = true; } }; setRenderer(new CheckBoxCellRenderer<CheckableItem>()); addActionListener(listener); getInputMap(JComponent.WHEN_FOCUSED).put( KeyStroke.getKeyStroke(KeyEvent.VK_SPACE, 0), "space-key-select"); getActionMap().put("space-key-select", new AbstractAction() { @Override public void actionPerformed(ActionEvent e) { System.out.println("JComboBox#getSelectedIndex()" + getSelectedIndex()); Accessible a = getAccessibleContext().getAccessibleChild(0); if (a instanceof BasicComboPopup) { BasicComboPopup pop = (BasicComboPopup) a; int i = pop.getList().getSelectedIndex(); System.out.println("JList#getSelectedIndex() " + i); updateItem(i); } } }); } private void updateItem(int index) { if (isPopupVisible()) { E item = getItemAt(index); item.selected ^= true; removeItemAt(index); insertItemAt(item, index); setSelectedItem(item); } } @Override public void setPopupVisible(boolean v) { if (shouldntClose) { shouldntClose = false; return; } else { super.setPopupVisible(v); } } }

使用复选框创建JComboBox

1 个答案: