概要

JComboBoxのドロップダウンリストに表示するItemTree状に配置します。

スクリーンショット

TreeComboBox.png

サンプルコード

class TreeComboBox<E extends TreeNode> extends JComboBox<E> {
  private boolean isNotSelectableIndex;
  private final Action up = new AbstractAction() {
    @Override public void actionPerformed(ActionEvent e) {
      int si = getSelectedIndex();
      for (int i = si - 1; i >= 0; i--) {
        if (getItemAt(i).isLeaf()) {
          setSelectedIndex(i);
          break;
        }
      }
    }
  };

  private final Action down = new AbstractAction() {
    @Override public void actionPerformed(ActionEvent e) {
      int si = getSelectedIndex();
      for (int i = si + 1; i < getModel().getSize(); i++) {
        if (getItemAt(i).isLeaf()) {
          setSelectedIndex(i);
          break;
        }
      }
    }
  };

  @Override public void updateUI() {
    super.updateUI();
    ListCellRenderer<? super E> renderer = getRenderer();
    setRenderer(new ListCellRenderer<E>() {
      @Override public Component getListCellRendererComponent(
          JList<? extends E> list, E value, int index,
          boolean isSelected, boolean cellHasFocus) {
        JLabel l = (JLabel) renderer.getListCellRendererComponent(
            list, value, index, isSelected, cellHasFocus);
        l.setBorder(BorderFactory.createEmptyBorder(1, 1, 1, 1));
        if (index >= 0 && value instanceof DefaultMutableTreeNode) {
          DefaultMutableTreeNode node = (DefaultMutableTreeNode) value;
          int indent = Math.max(0, node.getLevel() - 1) * 16;
          l.setBorder(BorderFactory.createEmptyBorder(1, indent + 1, 1, 1));
          if (!value.isLeaf()) {
            l.setForeground(Color.WHITE);
            l.setBackground(Color.GRAY.darker());
          }
        }
        return l;
      }
    });
    EventQueue.invokeLater(() -> {
      ActionMap am = getActionMap();
      am.put("selectPrevious3", up);
      am.put("selectNext3", down);
      InputMap im = getInputMap();
      im.put(KeyStroke.getKeyStroke(KeyEvent.VK_UP, 0), "selectPrevious3");
      im.put(KeyStroke.getKeyStroke(KeyEvent.VK_KP_UP, 0), "selectPrevious3");
      im.put(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, 0), "selectNext3");
      im.put(KeyStroke.getKeyStroke(KeyEvent.VK_KP_DOWN, 0), "selectNext3");
    });
  }

  @Override public void setPopupVisible(boolean v) {
    if (!v && isNotSelectableIndex) {
      isNotSelectableIndex = false;
    } else {
      super.setPopupVisible(v);
    }
  }

  @Override public void setSelectedIndex(int index) {
    TreeNode node = getItemAt(index);
    if (Objects.nonNull(node) && node.isLeaf()) {
      super.setSelectedIndex(index);
    } else {
      isNotSelectableIndex = true;
    }
  }
}
view all

解説

上記のサンプルでは、TreeModelから取得したTreeNodeJComboBoxItemとして、ドロップダウンリストに表示しています。

  • TreeNode#isLeaf()の場合だけ、選択可能
  • 0レベルのルートノードは非表示で、第1レベルノードのインデントは0に設定
  • 2レベル以降の子ノードのインデントはBorderFactory.createEmptyBorder(1, indent + 1, 1, 1)で設定

  • TreeCellRendererを使用してノードアイコンなどを表示する場合のサンプル
import java.awt.*;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Objects;
import java.util.stream.Collectors;
import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.TreeCellRenderer;

public final class TreeComboBoxTest {
  private Component makeUI() {
    DefaultMutableTreeNode root = (DefaultMutableTreeNode) new JTree().getModel().getRoot();
    JPanel p = new JPanel(new BorderLayout());
    p.add(new TreeComboBox(root), BorderLayout.NORTH);
    p.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5));
    return p;
  }

  public static void main(String[] args) {
    EventQueue.invokeLater(() -> {
      try {
        UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
      } catch(Exception ex) {
        throw new IllegalArgumentException(ex);
      }
      JFrame f = new JFrame();
      f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
      f.getContentPane().add(new TreeComboBoxTest().makeUI());
      f.setSize(320, 240);
      f.setLocationRelativeTo(null);
      f.setVisible(true);
    });
  }
}

class TreeComboBox extends JComboBox<DefaultMutableTreeNode> {
  public TreeComboBox(DefaultMutableTreeNode root) {
    super();
    DefaultComboBoxModel<DefaultMutableTreeNode> m = new DefaultComboBoxModel<>();
    Collections.list((Enumeration<?>) root.preorderEnumeration()).stream()
        .filter(DefaultMutableTreeNode.class::isInstance)
        .map(DefaultMutableTreeNode.class::cast)
        .filter(n -> !n.isRoot())
        .forEach(m::addElement);
    setModel(m);
  }

  @Override
  public void updateUI() {
    super.updateUI();
    JTree dummyTree = new JTree();
    TreeCellRenderer renderer = dummyTree.getCellRenderer();
    ListCellRenderer<? super DefaultMutableTreeNode> r = getRenderer();
    setRenderer((list, value, index, isSelected, cellHasFocus) -> {
      Component c = r.getListCellRendererComponent(list, value, index, isSelected, cellHasFocus);
      if (value == null) {
        return c;
      }
      if (index < 0) {
        String txt = Arrays.stream(value.getPath())
            .filter(DefaultMutableTreeNode.class::isInstance)
            .map(DefaultMutableTreeNode.class::cast)
            .filter(n -> !n.isRoot())
            .map(Objects::toString)
            .collect(Collectors.joining(" / "));
        ((JLabel) c).setText(txt);
        return c;
      } else {
        boolean leaf = value.isLeaf();
        JLabel l = (JLabel) renderer.getTreeCellRendererComponent(
            dummyTree, value, isSelected, true, leaf, index, false);
        int childIndent = UIManager.getInt("Tree.leftChildIndent") +
                          UIManager.getInt("Tree.rightChildIndent");
        int indent = Math.max(0, value.getLevel() - 1) * childIndent;
        l.setBorder(BorderFactory.createEmptyBorder(1, indent + 1, 1, 1));
        return l;
      }
    });
  }
}

参考リンク

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