Can't see components in JScrollPane

问题

I'm using a JScrollPane to hold a JTextArea for a large area of text. I add the TextArea directly to the JFrame, it works fine. But I add it to the scrollpane and add the scrollpane, I don't see the textarea. Here's my SSCCE:

public class foo extends JFrame{
    //gui elements
JTextArea chatMonitor = new JTextArea();

JScrollPane textPane = new JScrollPane();

ChatFrame(final String nickname, final String login, final String server, final String channel){
    setSize(500,500);
    chatMonitor.setEditable(false);
    chatMonitor.setVisible(true);
    textPane.add(chatMonitor);
    textPane.setAutoscrolls(true);
    textPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
    textPane.setVisible(true);
    add(textPane);
}
}

回答1:

Assuming textPane is a JScrollPane, you should never be adding components to it.

Instead use JScrollPane#setViewportView(Component)

JScrollPane is made of a number components which work together to provide you the functionality required to make the component scrollable...

JScrollPane has a JViewport, which is used to contain the component you want to be scrolled. You need to "apply" the component to the view.

Take a closer look at How to use Scroll Panes for more details

来源：https://stackoverflow.com/questions/42527569/components-not-displaying-in-jscrollpane