Java Swing：JScrollPane无法正常工作 [英] Java Swing: JScrollPane not working

问题描述

我有一个包含一些字段的JPanel。 JPanel的高度是有限的所以我必须在它周围放置一个JScrollPane，以便人们可以向下滚动。

I have a JPanel which contains some fields. The height of the JPanel is limited so I have to put a JScrollPane around it so people can scroll down.

如下所示，它显示完美。但是你不能向下滚动（或向上）。

As you can see below, it displays perfectly. But you can't scroll down (or up).

DetailPanel detail = new DetailPanel();
JScrollPane jsp = new JScrollPane(detail);
jsp.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
jsp.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
jsp.setBounds(745, 10, 235, 225);
add(jsp);

详情面板：

private void init(){
            setLayout(null);
            setSize(140, 400);
            int x = 5, y = 0;
            for(int i = 0; i < lbls.length; i++) {
                JLabel lbl = new JLabel(lbls[i]);
                lbl.setBounds(x, y, 200, 25);
                add(lbl);
                fields[i] = new JTextField();
                fields[i].setBounds(x, y+26, 200, 25);
                add(fields[i]);
                y+=50;
            }
        }

推荐答案

您的DetailPanel没有布局管理器与之关联，这意味着当您向其添加子项时它不会展开，这意味着JScrollPane没有可以滚动的任何地方。在DetailPanel上调用 setLayout（）或覆盖 getPreferredSize（）以添加其子级的高度并返回有意义的价值。

Your DetailPanel has no layout manager associated with it, which means it doesn't expand when you add children to it, which means the JScrollPane doesn't have anywhere to scroll. Either call setLayout() on your DetailPanel or override getPreferredSize() to add up the heights of its children and return a meaningful value.

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