JTree - 如何将setBackground设置为节点

Question

我阅读了很多教程，但没有对我有所帮助。我有jTree工作和setForeground工作完美，但当我想setBackground所以jTree没有变化。你能帮我解决一下吗？感谢。

import java.awt.Color;
import java.awt.Component;

import javax.swing.Icon;
import javax.swing.ImageIcon;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;


public class UrlNodeRenderer extends DefaultTreeCellRenderer {

    public static Icon  icon    =  null;

    public UrlNodeRenderer() {
        icon = new ImageIcon(getClass().getResource("icon.png"));
    }

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

        setOpenIcon(icon);
        setClosedIcon(icon);
        setLeafIcon(icon);

        UrlTreeNode node = (UrlTreeNode) (((DefaultMutableTreeNode) value).getUserObject());
        if(node.isContainsPhrase()) {
            setForeground(Color.BLUE);
            setBackground(Color.PINK); // doesn't works
        }

        return this;
    }
}

Answer 1

您需要在TreeCellRenderer上使用setOpaque(true);来更改背景颜色。您可以将其添加到构造函数：

public UrlNodeRenderer() {
    icon = new ImageIcon(getClass().getResource("icon.png"));
    setOpaque(true);
}

编辑： 你需要改变背景颜色，如下所示：

 private class Renderer extends DefaultTreeCellRenderer{

        public  Renderer() {
            setOpaque(true);
        }
        @Override
        public Component getTreeCellRendererComponent(JTree tree, Object value,
                boolean selected, boolean expanded, boolean leaf, int row,
                boolean hasFocus) {

            super.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus);
            setBackground(selected ? Color.LIGHT_GRAY : 
                (leaf ? Color.GRAY : tree.getBackground()));
            return this;
        }

    }

在你的情况下：

if(node.isContainsPhrase()) {
        setForeground(Color.BLUE);
        setBackground(Color.PINK); // doesn't works
}

您将颜色设置为所有节点，因为您从不为false case设置颜色。