Valid Parentheses

 1 public class Solution {
 2     public boolean isValid(String s) {
 3         Stack stack=new Stack();
 4         for(int i=0;i<s.length();i++)
 5         {
 6             char ch=s.charAt(i);
 7             if(ch==‘(‘||ch==‘[‘||ch==‘{‘)
 8             {
 9                 stack.push(ch);
10             }
11             else
12             {
13                 if(!stack.isEmpty())
14                 {
15                     if(isEqual((char)stack.peek(),ch))
16                     {
17                         stack.pop();
18                     }
19                     else
20                         return false;
21                 }
22                 else
23                     return false;
24             }
25         }
26         return stack.isEmpty()?true:false;
27     }
28         public  boolean isEqual(char c1,char c2)
29     {
30         if(c1==‘[‘&&c2==‘]‘)return true;
31         else if(c1==‘(‘&&c2==‘)‘)return true;
32         else if(c1==‘{‘&&c2==‘}‘)return true;
33         return false;
34     }
35 }