根據自定義對象狀態更改JTree圖標

Question

我有一個基於幾個自定義類的JTree。 我想給幾個節點一個特定的圖標。 因此，我基於此鏈接執行了以下代碼： 動態更改JTree中特定節點的圖標

        DefaultTreeCellRenderer renderer = new DefaultTreeCellRenderer() {
        private static final long serialVersionUID = 1L;
        private Icon good = new ImageIcon(getClass().getResource("/good.png"));
        private Icon dunno = new ImageIcon(getClass().getResource("/dunno.png"));
        private Icon bad = new ImageIcon(getClass().getResource("/bad.png"));

        @Override
        public Component getTreeCellRendererComponent(JTree tree,
            Object value, boolean selected, boolean expanded,
            boolean isLeaf, int row, boolean focused) {

            Component c = super.getTreeCellRendererComponent(tree, value, selected, expanded, isLeaf, row, focused);

            // JTreePanelNode node = (JTreePanelNode)c; - not possible
            return c;
        }
    };
    this.getTree().setCellRenderer(renderer);   

我的每個節點都是JTreePanelNode（自定義類）的對象，該對象保存可以通過setState（String s）設置並通過getState（）獲取的特定狀態。 所以我想要的是這樣的事情：

if(node.getState().equals("good")) ..
else if(node.getState.equals("bad")) ..
else ..

我怎樣才能實現這樣的目標？ 據我了解，渲染器使用getTreeCellRendererComponent遍歷每個節點，並應用一個特定的圖標，我可以使用setIcon和多個ifs（）進行選擇。 但是我無法轉換為JTreePanelNode。 有什么辦法嗎？ 謝謝 ：）

Answer 1

全部取決於您的JTreePanelNode類。 如果它實現了TreeNode接口，那么您可以選擇：

public Component getTreeCellRendererComponent(JTree tree, Object value,
        boolean sel, boolean expanded, boolean leaf, int row,
        boolean hasFocus) {
    Component comp = super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf,
            row, hasFocus);
    TreeNode current = (TreeNode)value;

    if (leaf) {
        //set leaf icon
    } else if (expanded) {
        //set expanded icon
    } else {
        // set default state
    }

    if (hasFocus)
        //set what it looks like if focused

    else if (selected)
        //set what it looks like if selected

    else
        //set default l&f

    comp.setIcon(whatevericonset in above conditions);

    return comp;
}

當然，您可以根據節點class.getState（）添加更多狀態。

Answer 2

您可以訪問該樹中表示的對象：

@Override
public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean isLeaf, int row, boolean focused) {

    Component c = super.getTreeCellRendererComponent(tree, value, selected, expanded, isLeaf, row, focused);
    DefaultMutableTreeNode node = (DefaultMutableTreeNode ) value;
    Object representedObject = node.getUserObject();

    JLabel superLabel = super.getTreeCellRendererComponent();
    String text = label.getText();

    if(object.isGood() ){ //i don't know your code
        superLabel .setText (text +"goooooooood");
    }else{
        superLabel .setText (text +"badbadbabd");
    }
    return superLabel ;
}