Binary Tree java help please, with getRight and getLeft subtree.

[tonedog12345]

I can't figure out how to get these 2 methods to work. In my assignment description it says


public BinTree getLTree()

Get a reference to the left subtree. If this is not possible to do then throw an IllegalArgumentException.

NOTE

This routine returns a BinTree, not a Tnode. You will have to create a new BinTree and set its root to be a reference to the left subtree.
pre: fill this in...
post: fill this in...

Returns:
fill this in...


my BinTree constructors were correct and this is what they are


public BinTree()
{
root = null;
}


public BinTree( int val )
{
root = new Tnode( val, null, null );
}

this is what I put for the get functions

public BinTree getLTree()
{
if ( isEmpty() )
{
throw new IllegalArgumentException();
}
return new BinTree( root.getLkid().getVal() );
}

any suggestions please?

 

[Coin]

1. In future it would help a lot if you ask your question in a more specific way than just to say "it doesn't work". We kind of need to know in what way it fails to work or it is difficult to give advice.

2. One thing that does jump to mind though is that your problem statement says
"You will have to create a new BinTree and set its root to be a reference to the left subtree. "
But if you look at your code:
return new BinTree( root.getLkid().getVal() );
This is not what you do. What you do in that code is create a new BinTree and set its root to be a reference to a new subtree, containing a single node, with that node having the value of the root of the left subtree. This is quite different from what the problem asked for.

 

[quicknote]

I would suggest first checking your BinTree constructor and make sure it is correctly setting the root node. If the root is not set correctly, then your getLTree() method will not work as expected.

Next, I would recommend breaking down your getLTree() method into smaller steps and testing each step individually. For example, you can first try to get the left child node of the root and make sure it is not null. Then, try to retrieve the value of that left child node. If that works, then you can proceed to creating a new BinTree and setting its root to be a reference to the left subtree.

Additionally, make sure to properly handle cases where the left subtree is null. You can either return null or throw an exception in those cases. Also, make sure to clearly define the pre and post conditions for your method.

I would also suggest reaching out to your professor or classmates for further assistance and clarification on the assignment requirements. Good luck!