OnJava8-Examples/collectiontopics/ListOps.java

// collectiontopics/ListOps.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 Lists
import java.util.*;
import onjava.HTMLColors;

public class ListOps {
  // Create a short list for testing:
  static final List<String> LIST =
    HTMLColors.LIST.subList(0, 10);
  private static boolean b;
  private static String s;
  private static int i;
  private static Iterator<String> it;
  private static ListIterator<String> lit;
  public static void basicTest(List<String> a) {
    a.add(1, "x"); // Add at location 1
    a.add("x"); // Add at end
    // Add a collection:
    a.addAll(LIST);
    // Add a collection starting at location 3:
    a.addAll(3, LIST);
    b = a.contains("1"); // Is it in there?
    // Is the entire collection in there?
    b = a.containsAll(LIST);
    // Lists allow random access, which is cheap
    // for ArrayList, expensive for LinkedList:
    s = a.get(1); // Get (typed) object at location 1
    i = a.indexOf("1"); // Tell index of object
    b = a.isEmpty(); // Any elements inside?
    it = a.iterator(); // Ordinary Iterator
    lit = a.listIterator(); // ListIterator
    lit = a.listIterator(3); // Start at loc 3
    i = a.lastIndexOf("1"); // Last match
    a.remove(1); // Remove location 1
    a.remove("3"); // Remove this object
    a.set(1, "y"); // Set location 1 to "y"
    // Keep everything that's in the argument
    // (the intersection of the two sets):
    a.retainAll(LIST);
    // Remove everything that's in the argument:
    a.removeAll(LIST);
    i = a.size(); // How big is it?
    a.clear(); // Remove all elements
  }
  public static void iterMotion(List<String> a) {
    ListIterator<String> it = a.listIterator();
    b = it.hasNext();
    b = it.hasPrevious();
    s = it.next();
    i = it.nextIndex();
    s = it.previous();
    i = it.previousIndex();
  }
  public static void iterManipulation(List<String> a) {
    ListIterator<String> it = a.listIterator();
    it.add("47");
    // Must move to an element after add():
    it.next();
    // Remove the element after the new one:
    it.remove();
    // Must move to an element after remove():
    it.next();
    // Change the element after the deleted one:
    it.set("47");
  }
  public static void testVisual(List<String> a) {
    System.out.println(a);
    List<String> b = LIST;
    System.out.println("b = " + b);
    a.addAll(b);
    a.addAll(b);
    System.out.println(a);
    // Insert, remove, and replace elements
    // using a ListIterator:
    ListIterator<String> x =
      a.listIterator(a.size()/2);
    x.add("one");
    System.out.println(a);
    System.out.println(x.next());
    x.remove();
    System.out.println(x.next());
    x.set("47");
    System.out.println(a);
    // Traverse the list backwards:
    x = a.listIterator(a.size());
    while(x.hasPrevious())
      System.out.print(x.previous() + " ");
    System.out.println();
    System.out.println("testVisual finished");
  }
  // There are some things that only LinkedLists can do:
  public static void testLinkedList() {
    LinkedList<String> ll = new LinkedList<>();
    ll.addAll(LIST);
    System.out.println(ll);
    // Treat it like a stack, pushing:
    ll.addFirst("one");
    ll.addFirst("two");
    System.out.println(ll);
    // Like "peeking" at the top of a stack:
    System.out.println(ll.getFirst());
    // Like popping a stack:
    System.out.println(ll.removeFirst());
    System.out.println(ll.removeFirst());
    // Treat it like a queue, pulling elements
    // off the tail end:
    System.out.println(ll.removeLast());
    System.out.println(ll);
  }
  public static void main(String[] args) {
    // Make and fill a new list each time:
    basicTest(new LinkedList<>(LIST));
    basicTest(new ArrayList<>(LIST));
    iterMotion(new LinkedList<>(LIST));
    iterMotion(new ArrayList<>(LIST));
    iterManipulation(new LinkedList<>(LIST));
    iterManipulation(new ArrayList<>(LIST));
    testVisual(new LinkedList<>(LIST));
    testLinkedList();
  }
}
/* Output:
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue, BlueViolet]
b = [AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige,
Bisque, Black, BlanchedAlmond, Blue, BlueViolet]
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue, BlueViolet, AliceBlue,
AntiqueWhite, Aquamarine, Azure, Beige, Bisque, Black,
BlanchedAlmond, Blue, BlueViolet, AliceBlue, AntiqueWhite,
Aquamarine, Azure, Beige, Bisque, Black, BlanchedAlmond,
Blue, BlueViolet]
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue, BlueViolet, AliceBlue,
AntiqueWhite, Aquamarine, Azure, Beige, one, Bisque, Black,
BlanchedAlmond, Blue, BlueViolet, AliceBlue, AntiqueWhite,
Aquamarine, Azure, Beige, Bisque, Black, BlanchedAlmond,
Blue, BlueViolet]
Bisque
Black
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue, BlueViolet, AliceBlue,
AntiqueWhite, Aquamarine, Azure, Beige, one, 47,
BlanchedAlmond, Blue, BlueViolet, AliceBlue, AntiqueWhite,
Aquamarine, Azure, Beige, Bisque, Black, BlanchedAlmond,
Blue, BlueViolet]
BlueViolet Blue BlanchedAlmond Black Bisque Beige Azure
Aquamarine AntiqueWhite AliceBlue BlueViolet Blue
BlanchedAlmond 47 one Beige Azure Aquamarine AntiqueWhite
AliceBlue BlueViolet Blue BlanchedAlmond Black Bisque Beige
Azure Aquamarine AntiqueWhite AliceBlue
testVisual finished
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue, BlueViolet]
[two, one, AliceBlue, AntiqueWhite, Aquamarine, Azure,
Beige, Bisque, Black, BlanchedAlmond, Blue, BlueViolet]
two
two
one
BlueViolet
[AliceBlue, AntiqueWhite, Aquamarine, Azure, Beige, Bisque,
Black, BlanchedAlmond, Blue]
*/