Balanced Binary Tree leetcode java

 1     public int checkBalanced(TreeNode t){
 2         if(t==null)
 3             return 0;
 4             
 5         int leftheight = checkBalanced(t.left);
 6         if(leftheight == -1)
 7             return -1;
 8         
 9         int rightheight = checkBalanced(t.right);
10         if(rightheight == -1)
11             return -1;
12         
13         if(Math.abs(leftheight-rightheight)>1)
14             return -1;
15         else
16             return Math.max(leftheight,rightheight)+1;
17     }
18     
19     public boolean isBalanced(TreeNode root) {
20         if(checkBalanced(root) == -1)
21             return false;
22         else
23             return true;
24     }