OnJava8-Examples/collectiontopics/CollectionMethods.java

// collectiontopics/CollectionMethods.java
// (c)2017 MindView LLC: see Copyright.txt
// We make no guarantees that this code is fit for any purpose.
// Visit http://OnJava8.com for more book information.
// Things you can do with all Collections
import java.util.*;
import static onjava.HTMLColors.*;

public class CollectionMethods {
  public static void main(String[] args) {
    Collection<String> c =
        new ArrayList<>(LIST.subList(0, 4));
    c.add("ten");
    c.add("eleven");
    show(c);
    border();
    // Make an array from the List:
    Object[] array = c.toArray();
    // Make a String array from the List:
    String[] str = c.toArray(new String[0]);
    // Find max and min elements; this means
    // different things depending on the way
    // the Comparable interface is implemented:
    System.out.println(
      "Collections.max(c) = " + Collections.max(c));
    System.out.println(
      "Collections.min(c) = " + Collections.min(c));
    border();
    // Add a Collection to another Collection
    Collection<String> c2 =
        new ArrayList<>(LIST.subList(10, 14));
    c.addAll(c2);
    show(c);
    border();
    c.remove(LIST.get(0));
    show(c);
    border();
    // Remove all components that are
    // in the argument collection:
    c.removeAll(c2);
    show(c);
    border();
    c.addAll(c2);
    show(c);
    border();
    // Is an element in this Collection?
    String val = LIST.get(3);
    System.out.println(
      "c.contains(" + val  + ") = " + c.contains(val));
    // Is a Collection in this Collection?
    System.out.println(
      "c.containsAll(c2) = " + c.containsAll(c2));
    Collection<String> c3 =
      ((List<String>)c).subList(3, 5);
    // Keep all the elements that are in both
    // c2 and c3 (an intersection of sets):
    c2.retainAll(c3);
    show(c2);
    // Throw away all the elements
    // in c2 that also appear in c3:
    c2.removeAll(c3);
    System.out.println(
      "c2.isEmpty() = " +  c2.isEmpty());
    border();
    // Functional operation:
    c = new ArrayList<>(LIST);
    c.removeIf(s -> !s.startsWith("P"));
    c.removeIf(s -> s.startsWith("Pale"));
    // Stream operation:
    c.stream().forEach(System.out::println);
    c.clear(); // Remove all elements
    System.out.println("after c.clear():" + c);
  }
}
/* Output:
AliceBlue
AntiqueWhite
Aquamarine
Azure
ten
eleven
******************************
Collections.max(c) = ten
Collections.min(c) = AliceBlue
******************************
AliceBlue
AntiqueWhite
Aquamarine
Azure
ten
eleven
Brown
BurlyWood
CadetBlue
Chartreuse
******************************
AntiqueWhite
Aquamarine
Azure
ten
eleven
Brown
BurlyWood
CadetBlue
Chartreuse
******************************
AntiqueWhite
Aquamarine
Azure
ten
eleven
******************************
AntiqueWhite
Aquamarine
Azure
ten
eleven
Brown
BurlyWood
CadetBlue
Chartreuse
******************************
c.contains(Azure) = true
c.containsAll(c2) = true
c2.isEmpty() = true
******************************
PapayaWhip
PeachPuff
Peru
Pink
Plum
PowderBlue
Purple
after c.clear():[]
*/