public class TreeNode {
    private Integer x;
    private Integer y;
    private Tree tree;

    public TreeNode(Integer x, Integer y, Tree tree) {
        this.x = x;
        this.y = y;
        this.tree = tree;
    }

    public static void main(String[] args) {
        TreeNode treeNode1 = new TreeNode(10, 20, TreeFactory.getTree("name1", "data1"));
        TreeNode treeNode2 = new TreeNode(11, 21, TreeFactory.getTree("name1", "data1"));
        TreeNode treeNode3 = new TreeNode(12, 22, TreeFactory.getTree("name2", "data1"));
    }
}

@Getter
public class Tree {
    private final String name;
    private final String data;
    public Tree(String name, String data) {
        System.out.println("name = " + name + ", data = " + data);
        this.name = name;
        this.data= data;
    }
}

public class TreeFactory {
    private static Map<String, Tree> map = new ConcurrentHashMap<>();
    public static final Tree getTree(String name, String data) {
        if (map.containsKey(name)) {
            return map.get(name);
        }
        Tree tree = new Tree(name, data);
        map.put(name, tree);
        return tree;
    }
}

列印結果:

name = name1, data = data1
name = name2, data = data1