Implementing a binary tree data struct in java

Question

I'm trying to implement a binary tree data structure in java. This is my code. I'm very new to java and don't quite understand where my errors are. Thank you. I got this error message: binTree.java:21: error: class, interface, or enum expected

class Node {
int value;
Node left;
Node right;

Node(int value) {
    this.value = value;
    right = null;
    left = null;
}
}

public class BinTree {

Node root;

}
private Node addRecursive(Node current, int value) {
if (current == null) {
    return new Node(value);
}

if (value < current.value) {
    current.left = addRecursive(current.left, value);
} else if (value > current.value) {
    current.right = addRecursive(current.right, value);
} else {
    // value already exists
    return current;
}

return current;
}
public void add(int value) {
root = addRecursive(root, value);
}
System.out.println();
    System.out.println("testcase 1:");
    BinTree binTree2 = new BinTree();
    binTree2.insertNode(new Node(3));
    binTree2.insertNode(new Node(201));
    binTree2.insertNode(new Node(60));
    binTree2.insertNode(new Node(30));
    binTree2.insertNode(new Node(45));
    binTree2.treeWalk();

Fix your indentation and check your braces. In Java you can't have methods outside of a class, and you can't have statements outside of a method or initializer block. — Radiodef
– Radiodef, Commented Jul 9, 2018 at 23:38
Check this for complete step by step: baeldung.com/java-binary-tree — Sergei Sirik
– Sergei Sirik, Commented Jul 9, 2018 at 23:57

Sami Tahri · Accepted Answer · 2018-07-09 23:43:57Z

0

You used a closing bracket at the line 21 just after the Node root field where you shouldn't Also, you will need a main methods or Junit tedt case to launch your test (at the bottom, starting before your System.out.println())

answered Jul 9, 2018 at 23:43

Sami Tahri

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Comments

wade king · Accepted Answer · 2018-07-09 23:49:09Z

0

your methods need to be placed inside of the class BinTree and the code you want to execute needs to be wrapped in a main function like so

public class BinTree {

    Node root;


    private Node addRecursive(Node current, int value) {
        if (current == null) {
            return new Node(value);
        }

        if (value < current.value) {
            current.left = addRecursive(current.left, value);
        } else if (value > current.value) {
            current.right = addRecursive(current.right, value);
        } else {
        // value already exists
            return current;
        }

        return current;
    }

    public void add(int value) {
        root = addRecursive(root, value);
    }

    public static void main(String []args){
        System.out.println();
        System.out.println("testcase 1:");
        BinTree binTree2 = new BinTree();
        binTree2.insertNode(new Node(3));
        binTree2.insertNode(new Node(201));
        binTree2.insertNode(new Node(60));
        binTree2.insertNode(new Node(30));
        binTree2.insertNode(new Node(45));
        binTree2.treeWalk();
    }

}

It looks like you're missing some methods like insertNode and treeWalk but it should compile after you have implemented those.

answered Jul 9, 2018 at 23:49

wade king

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2 Comments

Blake Gorman Over a year ago

Thank you! Second question: How would I implement those methods?

wade king Over a year ago

Is this for a school assignment?

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