Java - How to Create a Binary Search Tree

this article represents the high level concept and code samples which could be used to create a binary search tree in java. please feel free to comment/suggest if i missed to mention one or more important points. also, sorry for the typos.

following are the key points described later in this article:

• what is a binary search tree?
• what are different kind of traversals?
• code samples

code sample – how to create a binary search tree

if the numbers such as {20, 15, 200, 25, -5, 0, 100, 20, 12, 126, 1000, -150} are to be stored in a binarytree (represented by code below), following would get printed using different kind of traversal mechanism:

//preorder traversal
20, 15, -5, -150, 0, 12, 200, 25, 20, 100, 126, 1000

// inorder traversal
-150, -5, 0, 12, 15, 20, 20, 25, 100, 126, 200, 1000

//postorder traversal
-150, 12, 0, -5, 15, 20, 126, 100, 25, 1000, 200, 20

following is the code for creating binary tree that uses following binarytree class and traversals:

binarytree tree = new binarytree( 20 );
int[] nums = {15, 200, 25, -5, 0, 100, 20, 12, 126, 1000, -150};
for(int i : nums ) {
tree.addnode( i );
}

tree.traversepreorder();
tree.traverseinorder();
tree.traversepostorder();

following is the code for binarytree class:

public class binarytree {

private int data;
private binarytree left;
private binarytree right;

public binarytree(int num) {
this.data = num;
this.left = null;
this.right = null;
}
// as a convention, if the key to be inserted is less than the key of root node, then key is inserted in
// left sub-tree; if key is greater, it is inserted in right sub-tree. if it is equal, as a convention, it 
// is inserted in right sub-tree
public void addnode(int num) {
if (num < this.data) {
if (this.left != null) {
this.left.addnode(num);
} else {
this.left = new binarytree(num);
}

} else {
if (this.right != null) {
this.right.addnode(num);
} else {
this.right = new binarytree(num);
}

}
}
// visit the node first, then left and right sub-trees
public void traversepreorder() {
system.out.println( this.data );
if( this.left != null ) {
this.left.traversepreorder();
}
if( this.right != null ) {
this.right.traversepreorder();
}
}
// visit left sub-tree, then node and then, right sub-tree
public void traverseinorder() {
if( this.left != null ) {
this.left.traverseinorder();
}
system.out.println( this.data );
if( this.right != null ) {
this.right.traverseinorder();
}
}
// visit left sub-tree, then right sub-tree and then the node
public void traversepostorder() {
if( this.left != null ) {
this.left.traversepostorder();
}
if( this.right != null ) {
this.right.traversepostorder();
}
system.out.println( this.data );
}

}