FlowLayout not flowing with JScrollPane around it

问题

I have a bunch of buttons on a JPanel using a FlowLayout. It looks really nice. When the buttons reach the right side of the panel they start out on a new row creating a nice 2-dimensional grid.

Here is the code:

    Container cp = getContentPane();
    JPanel panel = new JPanel();
    panel.setLayout(new FlowLayout());
    for (int i = 0; i < 20; i++)
        panel.add(new JButton("Button " + i));
    cp.add(panel);

However, the minute I put the panel in a scroll pane with only vertical scrolling:

    Container cp = getContentPane();
    JPanel panel = new JPanel();
    panel.setLayout(new FlowLayout());
    for (int i = 0; i < 20; i++)
        panel.add(new JButton("Button " + i));
    JScrollPane pane = new JScrollPane(
            panel,
            ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED,
            ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
    cp.add(pane);

the buttons are only shown in one row (and I can't even see the ones off to the right). I still want them to wrap. What is going on here? By the way, I need to show only the vertical scroll bar and no horizontal scroll bar. I want the buttons to wrap to a new row when they reach the right end.

回答1:

Check out my answer here: How can I let JToolBars wrap to the next line (FlowLayout) without them being hidden ty the JPanel below them?

There is a custom Flow Layout that I have used in this exact situation. Just plug it in and it wraps even in a scroll pane.

来源：https://stackoverflow.com/questions/5735577/flowlayout-not-flowing-with-jscrollpane-around-it