Recursive Tree

package q1;

public class MinTree {

    Tree tree = new Tree( 24,
                 new Tree( 45,
                     null ,
                     new Tree(8, null , null) ) ,
                 new Tree ( 17,
                     new Tree (74 , null , null ) ,
                     null ) );

    public static void main(String[] args){
    MinTree mt = new MinTree();
    System.out.println("Minimum is :" + mt.findMin());
    }

    public int findMin(){
        return findMinAux(tree);

    }

    private int findMinAux(Tree t) {
        int min;
        int minL;
        int minR;

        min = t.getVal();

        if(notEmpty(t.left())){
            minL = findMinAux(t.left());
        }
        else{
            minL = min;
        }

        if(notEmpty(t.right())){
            minR = findMinAux(t.right());
        }
        else{
            minR=min;
        }

        if(minL < min){
            min = minL;
        }

        if(minR < min){
            min = minR;
        }

        return min;
    }

    private boolean notEmpty(Tree t){
        if(t.equals(null)){
            return false;
        }
        else{
            return true;
        }
    }


class Tree {

   private int val;
   private Tree left, right;

   public Tree(int val, Tree left, Tree right){
     this.val = val;
     this.left = left;
     this.right = right;
   }

   public int getVal(){
      return val;
   }

   public Tree left(){
      return left;
   }

   public Tree right(){
      return right;
   }
}
}