[英]Is it possible to generate a JavaFX TreeItem's children dynamically based on a function?
I am currently working on my first TreeView
in JavaFX. 我目前正在使用JavaFX中的第一个
TreeView
。
The example given in the documentation is the following: 文档中给出的示例如下:
TreeItem<String> root = new TreeItem<String>("Root Node");
root.setExpanded(true);
root.getChildren().addAll(
new TreeItem<String>("Item 1"),
new TreeItem<String>("Item 2"),
new TreeItem<String>("Item 3")
);
TreeView<String> treeView = new TreeView<String>(root);
In this example, we build the TreeItem
tree structure manually, ie, calling getChildren()
on every node that has children and adding these. 在这个例子中,我们手动构建
TreeItem
树结构,即在每个有子节点的节点上调用getChildren()
并添加它们。
Is it possible to tell a TreeItem
to "dynamically" build its children? 是否有可能告诉
TreeItem
“动态”构建其子项? It would be perfect if I could define the parent-child-relationship as a function. 如果我可以将父子关系定义为函数,那将是完美的。
I would be looking for something like the following: 我会寻找类似以下的东西:
// Function that generates the child tree items for a given tree item
Function<TreeItem<MyData>, List<TreeItem<MyData>>> childFunction = parent -> {
List<TreeItem<MyData>> children = new ArrayList<>(
parent. // TreeItem<MyData>
getValue(). // MyData
getChildrenInMyData(). // List<MyData>
stream().
map(myDataChild -> new TreeItem<MyData>(myDataChild)))); // List<TreeItem<MyData>>
// The children should use the same child function
children.stream().forEach(treeItem -> treeItem.setChildFunction(childFunction));
return children;
};
TreeItem<MyData> root = new TreeItem<MyData>(myRootData);
root.setExpanded(true);
// THE IMPORTANT LINE:
// Instead of setting the children via .getChildren().addAll(...) I would like to set a "child function"
root.setChildFunction(childFunction);
TreeView<MyData> treeView = new TreeView<String>(root);
Since there is no built-in functionality for this (as pointed out by @kleopatra in the comments), I came up with the following TreeItem
implementation: 由于没有内置功能(正如@kleopatra在评论中所指出的),我提出了以下
TreeItem
实现:
public class AutomatedTreeItem<C, D> extends TreeItem<D> {
public AutomatedTreeItem(C container, Function<C, D> dataFunction, Function<C, Collection<? extends C>> childFunction) {
super(dataFunction.apply(container));
getChildren().addAll(childFunction.apply(container)
.stream()
.map(childContainer -> new AutomatedTreeItem<C, D>(childContainer, dataFunction, childFunction))
.collect(Collectors.toList()));
}
}
Example usage: 用法示例:
Function<MyData, MyData> dataFunction = c -> c;
Function<MyData, Collection<? extends MyData>> childFunction = c -> c.getChildren();
treeTableView.setRoot(new AutomatedTreeItem<MyData, MyData>(myRootData, dataFunction, childFunction));
Probably this will help someone in the future. 可能这将有助于未来的某些人。
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