当我使用 java.awt.Canvas 时，JSplitPane 不会调整大小？

Question

I have a simple example where I'm using java.awt.Canvas for components within a JSplitPane, and the JSplitPane won't allow adjustment. Could anyone explain why? (and more importantly, how to fix)

VerticalSplit.java:

import java.awt.BorderLayout;
import java.awt.Component;
import javax.swing.JPanel;
import javax.swing.JSplitPane;

abstract public class VerticalSplit {
    public VerticalSplit(JPanel panel)
    {
        panel.setLayout(new BorderLayout());
        JSplitPane jsp = new JSplitPane(JSplitPane.VERTICAL_SPLIT,
            createComponent1(), createComponent2());
        jsp.setResizeWeight(0.5);
        panel.add(jsp, BorderLayout.CENTER);
    }
    abstract protected Component createComponent1();
    abstract protected Component createComponent2();
}

CanvasTest1.java:

import java.awt.Canvas;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class CanvasTest1 extends VerticalSplit
{
    static public class PlainCanvas extends Canvas
    {
        @Override public void paint(Graphics g)
        {
            Dimension d = getSize();
            int h = getHeight();
            int w = getWidth();
            g.drawRect(0,0,w,h);
            g.drawLine(0,0,w,h);
            g.drawLine(0,h,w,0);
        }
    };

    public CanvasTest1(JPanel panel) {  super(panel); }

    @Override protected Component createComponent1() {
        return new PlainCanvas();
    }

    @Override protected Component createComponent2() {
        return new PlainCanvas();
    }

    public static void main(String[] args) {
        JPanel panel = new JPanel();
        CanvasTest1 test = new CanvasTest1(panel);

        JFrame frame = new JFrame(test.getClass().getName());
        frame.setContentPane(panel);

        frame.pack();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }
}

Answer 1

Changing from Canvas to JPanel (as @tulskiy suggested -- thanks.) made it work properly.