如何在 Java Swing 中自动滚动到底部
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How to auto scroll to bottom in Java Swing
提问by pathikrit
I have a simple JPanel with a JScrollPane (with vertical scrollbar as needed) on it.
我有一个简单的 JPanel，上面有一个 JScrollPane（根据需要带有垂直滚动条）。
Things get added to (or removed from) the JPanel and when it goes beyond the bottom of the panel, I want the JScrollPane to scroll down to the bottom automatically as needed or scroll up if some components go away from the panel.
东西被添加到（或从）JPanel 中删除，当它超出面板底部时，我希望 JScrollPane 根据需要自动向下滚动到底部，或者如果某些组件离开面板，则向上滚动。
How shall I do this? I am guessing I need some kind of listener which gets called whenever the JPanel height changes? Or is there something as simple as JScrollPanel.setAutoScroll(true)?
我该怎么做？我猜我需要某种监听器，它会在 JPanel 高度发生变化时被调用？或者有这么简单的事情JScrollPanel.setAutoScroll(true)吗？
采纳答案by camickr
When you add/remove components for a panel you should invoke revalidate() on the panel to make sure the components are laid out properly.
当您为面板添加/删除组件时，您应该调用面板上的 revalidate() 以确保组件布局正确。
Then, if you want to scroll to the bottom then you should be able to use:
然后，如果你想滚动到底部，那么你应该能够使用：
JScrollBar sb = scrollPane.getVerticalScrollBar();
sb.setValue( sb.getMaximum() );
回答by zerodefect
scrollPane.getVerticalScrollBar().addAdjustmentListener(new AdjustmentListener() {
public void adjustmentValueChanged(AdjustmentEvent e) {
e.getAdjustable().setValue(e.getAdjustable().getMaximum());
}
});
This would be the best. Found from JScrollPane and JList auto scroll
这将是最好的。从JScrollPane 和 JList 自动滚动中找到
回答by Matthias Braun
This is how I scroll all the way up or down automatically:
这就是我自动向上或向下滚动的方式：
/**
* Scrolls a {@code scrollPane} all the way up or down.
*
* @param scrollPane the scrollPane that we want to scroll up or down
* @param direction we scroll up if this is {@link ScrollDirection#UP},
* or down if it's {@link ScrollDirection#DOWN}
*/
public static void scroll(JScrollPane scrollPane, ScrollDirection direction) {
JScrollBar verticalBar = scrollPane.getVerticalScrollBar();
// If we want to scroll to the top, set this value to the minimum,
// else to the maximum
int topOrBottom = direction == ScrollDirection.UP ?
verticalBar.getMinimum() :
verticalBar.getMaximum();
AdjustmentListener scroller = new AdjustmentListener() {
@Override
public void adjustmentValueChanged(AdjustmentEvent e) {
Adjustable adjustable = e.getAdjustable();
adjustable.setValue(topOrBottom);
// We have to remove the listener, otherwise the
// user would be unable to scroll afterwards
verticalBar.removeAdjustmentListener(this);
}
};
verticalBar.addAdjustmentListener(scroller);
}
public enum ScrollDirection {
UP, DOWN
}
