add docs (examplehub#41)

realDuYuanChao · web-flow · commit 05fd2f9dbb48 · 2020-10-31T10:30:56.000+08:00
diff --git a/src/main/java/com/examplehub/datastructures/stack/Infix2Postfix.java b/src/main/java/com/examplehub/datastructures/stack/Infix2Postfix.java
@@ -3,6 +3,14 @@
 import java.util.Stack;
 
 public class Infix2Postfix {
+
+  /**
+   * Convert infix to postfix.
+   *
+   * @param infixExpression the infix expression.
+   * @return postfix expression.
+   * @throws Exception if infix expression is invalid.
+   */
   public static String infix2PostFix(String infixExpression) throws Exception {
     if (!BalancedParentheses.isBalanced(infixExpression)) {
       throw new Exception("invalid expression");
