Level Order Traversal of a Binary Tree in Java

BTreeLevelOrder.java

@@ -0,0 +1,101 @@
+class TreeNode   
+{  
+int val;  
+
+TreeNode left, right;  
+
+public TreeNode(int i)  
+{  
+val = i;  
+right = left = null;  
+}  
+}  
+
+public class BTreeLevelOrder    
+{  
+
+TreeNode r;  
+
+public BTreeLevelOrder() { r = null; }  
+
+void displayLevelOrder()  
+{  
+int ht = treeHeight(r);  
+int j;  
+
+for (j = 1; j <= ht; j++)  
+{  
+displayCurrentLevel(r, j);  
+}  
+}  
+
+int treeHeight(TreeNode r)  
+{  
+if (r == null)  
+{  
+return 0;  
+}  
+else   
+{  
+
+int lh = treeHeight(r.left);  
+int rh = treeHeight(r.right);  
+
+if (lh > rh)  
+{  
+return (lh + 1);  
+}  
+else  
+{  
+return (rh + 1);  
+}  
+}  
+}  
+
+void displayCurrentLevel(TreeNode r, int l)  
+{  
+
+if (r == null)  
+{  
+return;  
+}  
+
+if (l == 1)  
+{  
+System.out.print(r.val + " ");  
+}  
+
+else if (l > 1)   
+{  
+displayCurrentLevel(r.left, l - 1);  
+displayCurrentLevel(r.right, l - 1);  
+}  
+}  
+
+public static void main(String argvs[])  
+{  
+
+BTreeLevelOrder  tree = new BTreeLevelOrder ();  
+
+tree.r = new TreeNode(18);  
+
+tree.r.left = new TreeNode(20);  
+tree.r.right = new TreeNode(30);  
+tree.r.left.left = new TreeNode(60);  
+tree.r.left.right = new TreeNode(34);  
+tree.r.right.left = new TreeNode(45);  
+tree.r.right.right = new TreeNode(65);  
+tree.r.left.left.left = new TreeNode(12);  
+tree.r.left.left.right = new TreeNode(50);  
+tree.r.left.right.left = new TreeNode(98);  
+tree.r.left.right.right = new TreeNode(82);  
+tree.r.right.left.left = new TreeNode(31);  
+tree.r.right.left.right = new TreeNode(59);  
+tree.r.right.right.left = new TreeNode(71);  
+tree.r.right.right.right = new TreeNode(41);  
+
+
+System.out.println("Level order traversal of binary tree is ");  
+tree.displayLevelOrder();  
+}  
+}