JTree

Question

我阅读了很多教程，但对我没有帮助。我有 jTree 可以工作并且 setForeground 工作得很好但是当我想 setBackground 所以 jTree 没有变化。你能帮我看看应该怎么写吗。谢谢

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中：

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

编辑：您需要在 false 和 true 情况下更改背景颜色，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;
        }

    }

你的情况：

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

您为所有节点设置了颜色，因为您从未为错误的情况设置颜色。

JTree - 如何将背景设置为节点

JTree - how to setBackground to node

java

swing

background