GeeksForGeeks Print all combinations of balanced parentheses

Question reference

http://www.geeksforgeeks.org/print-all-combinations-of-balanced-parentheses/

Write a function to generate all possible n pairs of balanced parentheses. 

For example, if n=1
{}
for n=2
{}{}
{{}}

I understood implementation from below  references

http://www.geeksforgeeks.org/print-all-combinations-of-balanced-parentheses/

https://discuss.leetcode.com/topic/8724/easy-to-understand-java-backtracking-solution/2

Solution in Java

View point is that the no of "(" is equal to ")"

package generate_all_paranthesis;

import java.util.*;

public class Solution1 {

public ArrayList<String> generateParenthesis(int a) 

{

    ArrayList<String> res = new ArrayList<String>();

    if(a==0)

    {

    return res;

    }    

    backtracking(0,0,a,new StringBuilder(),res);

    return res;

}

public static void backtracking(int open,int close,int a,StringBuilder temp,ArrayList<String> res)

{

if(close==a)

{

res.add(temp.toString());

return;

}

else

{

           //go on adding ")" if open > close

if(open>close)

{

                                //appending ")"
                temp.append(")");

backtracking(open, close+1, a, temp, res);

temp.setLength(temp.length()-1);

                                //removing ")"

}

           //go on adding "(" if open <n

if(open<a)

{

                                //appending "("

                                temp.append("(");

backtracking(open+1, close, a, temp, res);

temp.setLength(temp.length()-1);

                                //removing "("

}

}

}

public static void main(String[] args) {

// TODO Auto-generated method stub

      Solution1 s1 = new Solution1();

      System.out.println(s1.generateParenthesis(3));

}

}