CODEWITHSUNDEEP
javabinary-treebinary-search-tree
Keselme
Keselme

Reputation: 4249

Searching Binary Tree with a While loop

I am trying to write a function that searches for a value on a tree I built, I have written a recursive function that works fine. Now I want to improve my running time, so I want to use while loop to look for the value. The problem is that I'm getting NullPointerException. I know for sure that the tree is ok, because before I perform the search I print all the values. So what's the problem with my code?

public void SearchByLoop(Node root,final int val){

        while(root != null || root.getVal() == val){

            if(root.getVal() < val)

                root = root.getRightChild();

            else if(root.getVal() > val)

                root = root.getLeftChild();

        }

        if(root == null)

            System.out.println("Couldn't find value " + val);

        else if(root.getVal() == val)

                System.out.println("Found value " + val);

    }

public class Main {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Tree theTree = new Tree();
    Random rand = new Random();//Create random variable.
    int val = 0; 
    for(int i = 0 ; i < 100; i ++){

        val = rand.nextInt(151) + (0);
        theTree.addNode(val,"a");
    }
    theTree.inOrderTraverseTree(theTree.getRoot());
    theTree.SearchByLoop(theTree.getRoot(), 10);

}
}

Now, the inOrderTraverse method prints all of the values, so I know that the tree is ok. What can be the problem? Thank you!

Upvotes: 0

Views: 5259

Answers (1)

Eran
Eran

Reputation: 393811

This condition

while(root != null || root.getVal() == val)

will give you a NullPointerException when root is null.

You probably want

while(root != null && root.getVal() != val)

Upvotes: 3

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