Question

我正在自定义一个JTree，因此一些节点有复选框，使用santhosh tekuri's work作为基础。

所以我的想法是编写一个自定义的TreeCellRenderer，在这种情况下扩展JPanel并实现TreeCellRenderer，然后在getTreeCellRendererComponent方法中，我必须为每个节点决定是否接收复选框。

我已经看到一些典型JTree的其他示例来自定义每个节点图标，但是它们在将每个节点转换为JLabel并获取其文本时进行中继，而这里是JPanel。

这是我的渲染器的样子：

public class CheckTreeCellRenderer extends JPanel implements TreeCellRenderer{

    private CheckTreeSelectionModel selectionModel;
    private TreeCellRenderer delegate;
    private TristateCheckBox checkBox;
    protected CheckTreeManager.CheckBoxCustomizer checkBoxCustomer;


    public CheckTreeCellRenderer(TreeCellRenderer delegate, CheckTreeSelectionModel selectionModel){
        this.delegate = delegate;
        this.selectionModel = selectionModel;
        this.checkBox = new TristateCheckBox("");
        this.checkBox.setOpaque(false);
        setLayout(new BorderLayout());
        setOpaque(false);
    }


    public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus){
        Component renderer = delegate.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus);

        // Inside this if clause, those cells which do not require checkbox will be returned
        if({CODE_TO_GET_NODE_TEXT}.startsWith("A")){
            return renderer;
        }

        TreePath path = tree.getPathForRow(row);
        if(path != null){
            if(checkBoxCustomer != null && !checkBoxCustomer.showCheckBox(path)){
                return renderer;
            }
            if(selectionModel.isPathSelected(path, selectionModel.isDigged())){
                checkBox.getTristateModel().setState(TristateState.SELECTED);
            }
            else{
                checkBox.getTristateModel().setState(selectionModel.isDigged() && selectionModel.isPartiallySelected(path) ? TristateState.INDETERMINATE : TristateState.DESELECTED);
            }
        }
        removeAll();
        add(checkBox, BorderLayout.WEST);
        add(renderer, BorderLayout.CENTER);

        return this;
    }
}

在这种情况下，我想避免为那些文本以＆＃34; A＆＃34;开头的单元格设置一个Tristate复选框。举个例子。但是我找不到从值参数中获取文本的方法。

如果它有帮助，这就是我创建JTree的方式：

DefaultMutableTreeNode root = new DefaultMutableTreeNode();
JTree tree = new JTree(root);

// Add nodes to the tree
DefaultMutableTreeNode friends_node = new DefaultMutableTreeNode("Friends");
    friends_node.add(new DefaultMutableTreeNode("Anna"));
    friends_node.add(new DefaultMutableTreeNode("Amador"));
    friends_node.add(new DefaultMutableTreeNode("Jonas"));
    friends_node.add(new DefaultMutableTreeNode("Mike"));
    friends_node.add(new DefaultMutableTreeNode("Anthony"));
    friends_node.add(new DefaultMutableTreeNode("Maya"));
    friends_node.add(new DefaultMutableTreeNode("Pepe Vinyuela"));
root.add(friends_node);

tree.setCellRenderer(renderer = new CheckTreeCellRenderer(tree.getCellRenderer(), new CheckTreeSelectionModel(tree.getModel(), dig)));

有什么想法吗？

Answer 1

如果您使用的是String userObject = "Anna"; new DefaultMutableTreeNode(userObject);，那么您可以使用DefaultMutableTreeNode#getUserObject()方法：

@Override public Component getTreeCellRendererComponent(
    JTree tree, Object value, boolean selected, boolean expanded,
    boolean leaf, int row, boolean hasFocus) {
  Component renderer = delegate.getTreeCellRendererComponent(
    tree, value, selected, expanded, leaf, row, hasFocus);
  if (value instanceof DefaultMutableTreeNode) {
    Object userObject = ((DefaultMutableTreeNode) value).getUserObject();
    // Inside this if clause, those cells which do not require checkbox will be returned
    if(userObject instanceof String && ((String) userObject).startsWith("A")){
      return renderer;
    }
    //...

从自定义渲染器中获取方法getTreeCellRendererComponent中的JTree节点文本

1 个答案: