On Fri, 22 Aug 2025 03:53:13 GMT, Prasanta Sadhukhan <psadhuk...@openjdk.org> wrote:
> When the component orientation is changed from LTR to RTL or the other way > around, JSplitPane exchanges the left and right components. However, it does > this by adding and removing components instead of swapping the leftComponent > and rightComponent fields which results in leftComponent field is left as > null. > > This is because when JSplitPane calls `setLeftComponent(rightComponent)` it > calls `JSplitPane.addImpl` which calls `super.addImpl` > which [removes] > https://github.com/openjdk/jdk/blob/f423e1d9ad37135abacb8deb2d2151e21768a23e/src/java.desktop/share/classes/java/awt/Container.java#L1118 > the component from the JSplitPane as it calls `JSplitPane.remove` so the > sequence is > At start `leftComponent = Red, rightComponent = Green` > > before `super.addImpl` is called in `JSplitPane.addImpl` the > > `leftComponent = Green, rightComponent = Green` > > After super.addImpl is called, it calls [JSplitPane.remove] > (https://github.com/openjdk/jdk/blob/f423e1d9ad37135abacb8deb2d2151e21768a23e/src/java.desktop/share/classes/javax/swing/JSplitPane.java#L918) > where it sets > leftComponent = null. > > so we have > leftComponent = null, rightComponent = Green and then it calls [super.remove] > (https://github.com/openjdk/jdk/blob/f423e1d9ad37135abacb8deb2d2151e21768a23e/src/java.desktop/share/classes/javax/swing/JSplitPane.java#L922) > which calls `JSplitPane.remove(index)` and since index=1 because "Green" is > 1 it removes rightComponent > so we have now > leftComponent = null, rightComponent = null > > so when we now call > [setRightComponent](https://github.com/openjdk/jdk/blob/f423e1d9ad37135abacb8deb2d2151e21768a23e/src/java.desktop/share/classes/javax/swing/JSplitPane.java#L382) > it sets rightComponent to Red but leftComponent is not set and is still null. > > So fix is to just swap the left and right component in > setComponentOrientation call itself without using Container add/remove > components src/java.desktop/share/classes/javax/swing/JSplitPane.java line 374: > 372: ComponentOrientation curOrn = this.getComponentOrientation(); > 373: super.setComponentOrientation(orientation); > 374: Component comp = null; Rename comp to tmp? Or swap? And also reduce its scope by moving the declaration where it is assigned, this makes the code clearer. Maybe use var even? ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/26893#discussion_r2293530774
