As usual, create a public class called YourBinaryTree that extends BinaryTree, override public boolean equals(Object other), and implement it as described above. If other is null or not a BinaryTree you should return false. As a reminder you can access protected BinaryTree instance variables in equals, including on other, which you will need to do to start the recursion on other.

// YourBinaryTree class implementation

public class YourBinaryTree extends BinaryTree

{

// equals method implementation

Override

public boolean equals(Object other)

{

// if other is null or not a BinaryTree, then return false

if (other == null || !(other instanceof BinaryTree))

{

return false;

}

// if both classes are not same, then return false

if(getClass() != other.getClass())

return false;

// caste other object to YourBinaryTree

YourBinaryTree otherBinaryTree = (YourBinaryTree) other;

// call the equals recursive helper method

return equals(root, otherBinaryTree.root);

} // end of equals method

// equals recursive helper method implementation

private boolean equals(Node root1, Node root2)

{

// return true if the current nodes of both trees are null

if(root1 == null && root2 == null)

{

return true;

}

// return false if one current node is null and another current node is not null

if((root1 != null && root2 == null) || (root1 == null && root2 != null))

{

return false;

}

// return false if the values at the current nods of both trees are not equal

if(!(root1.value.equals(root2.value)))

return false;

else

// recursive calls to the equals recursive helper method for left and right subtrees

return (equals(root1.left, root2.left) && equals(root1.right, root2.right));

} // end of equals recursive helper method

} // end of YourBinaryTree class

Explanation:

This works only if you cast BinaryTree instead of YourBinaryTree in the first public boolean equals(Object other)

The program takes in or accepts public class called YourBinaryTree that extends BinaryTree, override public boolean equals(Object other), and implement it as described above. If other is null or not a BinaryTree you should return false.

add the following