How to implement a tree data-structure in Java?

Question

Is there any standard Java library class to represent a tree in Java?

Specifically I need to represent the following:

• The sub-tree at any node can have

Answer 1

Since the question asks for an available data structure, a tree can be constructed from lists or arrays:

Object[] tree = new Object[2];
tree[0] = "Hello";
{
  Object[] subtree = new Object[2];
  subtree[0] = "Goodbye";
  subtree[1] = "";
  tree[1] = subtree;
}

instanceof can be used to determine whether an element is a subtree or a terminal node.