Example04a.java

package com.study.collection;

import java.util.*;

public class Example04a {

  static void printCollection(String s, Collection<String> c) {
    String[] a = c.toArray(new String[0]);
    Arrays.sort(a);
    System.out.printf("%s: %s\n", s, Arrays.toString(a));
  }

  public static void main(String[] args) {

    Collection<String> c1 = new Stack<>();
    Collection<String> c2 = new LinkedList<>();
    Collection<String> c3 = new ArrayList<>();

    for (int i = 0; i < 20; i += 2) {
      String s = String.format("%02d", i);
      c1.add(s);
    }
    printCollection("c1 (2의 배수)", c1);

    for (int i = 0; i < 20; i += 3) {
      String s = String.format("%02d", i);
      c2.add(s);
    }
    printCollection("c2 (3의 배수)", c2);


    c3.clear();
    c3.addAll(c1);
    c3.retainAll(c2);
    printCollection("c1, c2 교집합", c3);

    c3.clear();
    c3.addAll(c1);
    c3.removeAll(c2);
    printCollection("c1, c2 차집합", c3);

    c3.clear();
    c3.addAll(c2);
    c3.removeAll(c1);
    printCollection("c2, c1 차집합", c3);

    c3.clear();
    c3.addAll(c1);
    c3.removeAll(c2);
    c3.addAll(c2);
    printCollection("c1, c2 합집합", c3);

  }
}