leetcode longest common prefix(easy) /java

import java.io.*;
import java.util.*;

public class Solution
{
    public static String longestCommonPrefix(String[] strs)
    {
        String r=new String("");
        int len=strs.length;
        if(len==0)
            return r;
        int i,j;
        String temp=strs[0];
        int limit=temp.length();
        int index=0;
        for(i=1;i<len;i++)
        {
            temp=strs[i];
            if(temp.length()<limit)
            {
                limit=temp.length();
                index=i;
            }

        }
        if(limit==0)
            return r;
        char c,d;
        boolean flag=true;

        for(i=0;i<limit;i++)
        {
            c=strs[index].charAt(i);
            for(j=0;j<len;j++)
            {
                d=strs[j].charAt(i);
                if(c!=d)
                    flag=false;


            }
            if(flag==false)
                break;
            else
                    r=r+String.valueOf(c);
        }
        return r;
    }


    public static void main(String[] args)
    {
        Scanner input=new Scanner(System.in);
        String s=new String("hz");
        String[] strs={"ca","a"};
        s=longestCommonPrefix(strs);
        System.out.println(s);
    }
}