JavaFX TreeView的嵌套路徑

Question

關於如何將嵌套路徑表示為TreeItems的任何想法？

這是我輸入的幾個字符串（此外：我之前不知道字符串，所以整個過程應該盡可能通用）：

input1
input2.sub1
input2.sub2
input2.sub2.subsub1
input2.sub3
input3
input3.sub1
input3.sub1.subsub1
input3.sub1.subsub1.subsubsub1
input3.sub2

由於目前正在路上，很遺憾，我無法發布任何源代碼。 但是在詢問之前，我嘗試了幾種方法，例如將路徑直接傳輸到TreeView（似乎很復雜），或者首先在Java中使用某種樹表示形式（大多數都是使用遞歸方法）。

所附的屏幕截圖顯示了我嘗試以通用方式實現的目標。

在此先感謝您-德國的良好祝願:)

Answer 1

您可以遍歷字符串列表，用定界符（ . ）分隔每個字符串，然后搜索樹，並根據需要添加項目。 就像是：

List<String> paths = ... ;
TreeItem<String> root = new TreeItem<>("root");
for (String path : paths) {
    TreeItem<String> current = root ;
    for (String component : path.split("\\.")) {
        current = getOrCreateChild(current, component);
    }
}

// ...

private TreeItem<String> getOrCreateChild(TreeItem<String> parent, String value) {

    for (TreeItem<String> child : parent.getChildren()) {
        if (value.equals(child.getValue())) {
            return child ;
        }
    }
    TreeItem<String> newChild = new TreeItem<>(value);
    parent.getChildren().add(newChild);
    return newChild ;
}

請注意，這里的字符串沒有什么特別的，您可以使用任何類型的字符串來完成。 這是使用該方法的通用版本的SSCCE：

import java.util.Arrays;
import java.util.List;
import java.util.function.Function;

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.stage.Stage;

public class TreeFromPaths extends Application {

    private final List<String> paths = Arrays.asList(
            "input1",
            "input2.sub1",
            "input2.sub2",
            "input2.sub2.subsub1",
            "input2.sub3",
            "input3",
            "input3.sub1",
            "input3.sub1.subsub1",
            "input3.sub1.subsub1.subsubsub1",
            "input3.sub2"
    );

    private <S,T> TreeView<T> createTree(
            List<S> paths, 
            Function<S, ? extends Iterable<T>> pathSplitter, 
            T rootValue) {

        TreeItem<T> root = new TreeItem<>(rootValue);
        populateTree(paths, pathSplitter, root);
        TreeView<T> tree = new TreeView<>(root);
        tree.setShowRoot(false);
        return tree;
    }

    private <S,T> void populateTree(
            List<S> paths, 
            Function<S, ? extends Iterable<T>> pathSplitter, 
            TreeItem<T> root) {

        for (S path : paths) {
            TreeItem<T> current = root ;
            for (T component : pathSplitter.apply(path)) {
                current = getOrCreateChild(current, component);
            }
        }
    }

    private <T> TreeItem<T> getOrCreateChild(TreeItem<T> parent, T value) {
        for (TreeItem<T> child : parent.getChildren()) {
            if (value.equals(child.getValue())) {
                return child ;
            }
        }
        TreeItem<T> newChild = new TreeItem<>(value);
        parent.getChildren().add(newChild);
        return newChild ;
    }

    @Override
    public void start(Stage primaryStage) {

        Function<String, List<String>> pathSplitter = 
            path -> Arrays.asList(path.split("\\."));

        TreeView<String> treeView = createTree(paths, pathSplitter, "root");

        primaryStage.setScene(new Scene(treeView, 400, 400));
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
    }
}

Answer 2

將項目“路徑”存儲在地圖中，以便您可以查找它們，創建不存在的節點以及使用現有節點。 最簡單的方法是遞歸方法：

private static TreeItem<String> getItem(Map<String, TreeItem<String>> items, TreeItem<String> root, String itemPath) {
    TreeItem<String> result = items.get(itemPath);

    if (result == null) {
        // new item needs to be created

        int index = itemPath.lastIndexOf('.');

        result = new TreeItem<>(itemPath.substring(index + 1));
        items.put(itemPath, result);

        if (index == -1) {
            // no more subpaths => connect to root
            root.getChildren().add(result);
        } else {
            // find/create parent
            TreeItem<String> parent = getItem(items, root, itemPath.substring(0, index));

            parent.getChildren().add(result);
        }
    }

    return result;

}

@Override
public void start(Stage primaryStage) throws Exception {
    List<String> paths = Arrays.asList(
            "input1",
            "input2.sub1",
            "input2.sub2",
            "input2.sub2.subsub1",
            "input2.sub3",
            "input3",
            "input3.sub1",
            "input3.sub1.subsub1",
            "input3.sub1.subsub1.subsubsub1",
            "input3.sub2");

    TreeItem<String> root = new TreeItem<>();
    Map<String, TreeItem<String>> items = new HashMap<>();

    for (String path : paths) {
        getItem(items, root, path);
    }

    TreeView<String> treeView = new TreeView<>(root);
    treeView.setShowRoot(false);
    Scene scene = new Scene(treeView);
    primaryStage.setScene(scene);
    primaryStage.show();
}