почему?
package com.javarush.task.pro.task05.task0508;
import java.util.Scanner;
/*
Удаляем одинаковые строки
*/
public class Solution {
public static String[] strings;
public static void main(String[] args) {
Scanner s = new Scanner(System.in);
int a = 6;
strings = new String[a];
for (int i = 0; i < a; i++) {
strings[i] = s.nextLine();
}
for (int i = 0; i < a; i++) {
if (strings[i] == null) continue;
String b = strings[i];
for (int j = 0; j < i; j++) {
if (strings[i] == null) continue;
else if (strings [j] == null) continue;
else if (strings[j].equals(b)) {
strings[j] = null;
strings[i] = null;
}
}
}
for (int i = 0; i < strings.length; i++) {
System.out.print(strings[i] + ", ");
}
}
}