import java.util.Hashtable;
import java.util.Map.Entry;
class DuplicateCharacter
{
public static void main(String[] args)
{
String str = "This is a string";
String[] arr = str.split(" ");
StringBuilder sb = new StringBuilder();
for(int i = 0 ; i < arr.length ; i++){
sb.append(arr[i]);
}
String send = sb.toString();
printDuplicate(send);
}
public static void printDuplicate(String str){
System.out.println(str);
str = str.toLowerCase();
Hashtable