JScrollPane.setviewportview与JScrollPane.add之间的区别 [英] Difference between JScrollPane.setviewportview vs JScrollPane.add

问题描述

我今天遇到了这个新事物，我不知道为什么。例如，当我想在面板中显示某些内容时，我只需将其添加到面板中;但为什么我不能直接添加表格滚动窗格，为什么我必须调用 setviewportview（）方法？什么 add（）方法做什么以及 setViewProtView（）做什么？

I faced this new thing today, and I didn't know why. When I want to show something in panel for example, I just add it to panel; but why I cannot add a table to scroll pane directly, and why I have to call the setviewportview() method? What does add() method do and what does setViewProtView() do?

推荐答案

基本上，你不应该使用 JScrollPane #add 。

Basically, you should not use JScrollPane#add.

JScrollPane 已经附加了一个组件， JViewport ，这就是 JScrollPane 用于显示添加到视口的任何组件。

JScrollPane has a single component already attached to it, a JViewport, this is what the JScrollPane uses to display any component added to the view port.

setViewportView 是一种方便的方法for for JScrollPane＃getViewport＃setView

setViewportView is a convenience method for for JScrollPane#getViewport#setView

基本概念归结为从滚动窗格的角度来看在视图中，它只显示一个组件，因此 add 实际上对它没有任何意义。该方法是从 JComponent延伸 - > 容器

The basic concept comes down to the fact that from the scroll panes point of view, it will only show a single component, so add doesn't actually make any sense for it. The method is a consequence of extending from JComponent -> Container

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