Testing the HashSet Class in Java

Problem:

Write a program that tests 10 of the 15 methods of HashSet class in java.

Output:

set.isEmpty(): true
[FR, US, RU, GB, CN]
set.size(): 5
set.contains("GB"): true
set.contains("JP"): false
set.isEmpty(): false
[FR, US, RU, BR, GB, CN]
[US, RU, BR, GB, CN]
US RU BR GB CN
[JP, FR, US, RU, GB, DE, IT, CA]
[US, RU, GB]
[BR, CN]
[US, RU, BR, GB, CN]
[]

Solution:

public class TestHashSet {
public static void main(String[] args) {
Set<String> set = new HashSet<String>();
System.out.printf("set.isEmpty(): %b%n", set.isEmpty());
Collections.addAll(set, "CN", "FR", "GB", "RU", "US");
System.out.println(set);
System.out.printf("set.size(): %d%n", set.size());
System.out.printf("set.contains(\"GB\"): %b%n", set.contains("GB"));
System.out.printf("set.contains(\"JP\"): %b%n", set.contains("JP"));
System.out.printf("set.isEmpty(): %b%n", set.isEmpty());
set.add("BR");
System.out.println(set);
set.remove("FR");
System.out.println(set);
String[] array = set.toArray(new String[0]);
for (String string : array) {
System.out.printf("%s ", string);
}
System.out.println("");
Set<String> g8 = new HashSet<String>();
Collections.addAll(g8, "CA", "DE", "FR", "GB", "IT", "JP", "RU", "US");
System.out.println(g8);
g8.retainAll(set);
System.out.println(g8);
set.removeAll(g8);
System.out.println(set);
set.addAll(g8);
System.out.println(set);
set.clear();
System.out.println(set);
}
}