please elaborate the test case my code is import java.util.*;
public class Main
{
public static void main(String args[])
{
int i;
char ch=’ ',ch1;
Scanner sc=new Scanner(System.in);
String s=sc.nextLine();
s=s.toLowerCase();
if(s.length()>=1&&s.length()<=1000)
{
for(ch1='a';ch1<='z';ch1++)
{
int k=0;
for(i=0;i<s.length();i++)
{
ch=s.charAt(i);
if(ch==ch1)
{
k++;
}
}
if(k>0)
{
System.out.print(ch1);
if(k>1)
System.out.print(k);
}
}
}
}
}