Binary Tree model code

package test;


public class tree2 {
    private int data;
    private tree2 lChild;
    private tree2 rChild;

    public int getNodes(){
        return (this.lChild == null ? 0 :
                this.lChild.getNodes( ) )
                + ( this.rChild == null
                ? 0 : this.rChild.getNodes( ) ) + 1;
    }
    public int sum(){
        return ( this.lChild == null ? 0 :
                this.lChild.sum( ) )
                + ( this.rChild == null ? 0 :
                this.rChild.sum( ) ) + this.data;
    }

    public void fTraverse( ) {
        System.out.print( this.data+" " );
        if( this.lChild != null ) {
            this.lChild.fTraverse( );
        }
        if( this.rChild != null ) {
            this.rChild.fTraverse( );
        }
    }
    public void mTraverse( ) {
        if( this.lChild != null ) {
            this.lChild.mTraverse( );
        }
        System.out.print( this.data+" " );
        if( this.rChild != null ) {
            this.rChild.mTraverse( );
        }
    }
    public void lTraverse( ) {
        if( this.lChild != null ) {
            this.lChild.lTraverse( );
        }
        if( this.rChild != null ) {
            this.rChild.lTraverse( );
        }
        System.out.print( this.data+" " );
    }

    public void addNode(tree2 node ) {
        if ( node.data< this.data ) {
            if ( this.lChild == null ) {
                this.lChild = node;
            } else {
                this.lChild.addNode( node );
            }
        }else if(node.data> this.data){
            if ( this.rChild == null ) {
                this.rChild = node;
            } else {
                this.rChild.addNode( node );
            }
        }

    }
    public tree2(int data) {
        this.data = data;
    }

    public int getData() {
        return data;
    }

    public void setData(int data) {
        this.data = data;
    }

    public tree2 getlChild() {
        return lChild;
    }

    public void setlChild(tree2 lChild) {
        this.lChild = lChild;
    }

    public tree2 getrChild() {
        return rChild;
    }

    public void setrChild(tree2 rChild) {
        this.rChild = rChild;
    }
}