//: containers/Lists.java // ©2015 MindView LLC: see Copyright.txt // Things you can do with Lists. import java.util.*; import net.mindview.util.*; import static net.mindview.util.Print.*; public class Lists { private static boolean b; private static String s; private static int i; private static Iterator it; private static ListIterator lit; public static void basicTest(List a) { a.add(1, "x"); // Add at location 1 a.add("x"); // Add at end // Add a collection: a.addAll(Countries.names(25)); // Add a collection starting at location 3: a.addAll(3, Countries.names(25)); b = a.contains("1"); // Is it in there? // Is the entire collection in there? b = a.containsAll(Countries.names(25)); // 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(Countries.names(25)); // Remove everything that's in the argument: a.removeAll(Countries.names(25)); i = a.size(); // How big is it? a.clear(); // Remove all elements } public static void iterMotion(List a) { ListIterator 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 a) { ListIterator it = a.listIterator(); it.add("47"); // Must move to an element after add(): it.next(); // Remove the element after the newly produced 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 a) { print(a); List b = Countries.names(25); print("b = " + b); a.addAll(b); a.addAll(b); print(a); // Insert, remove, and replace elements // using a ListIterator: ListIterator x = a.listIterator(a.size()/2); x.add("one"); print(a); print(x.next()); x.remove(); print(x.next()); x.set("47"); print(a); // Traverse the list backwards: x = a.listIterator(a.size()); while(x.hasPrevious()) printnb(x.previous() + " "); print(); print("testVisual finished"); } // There are some things that only LinkedLists can do: public static void testLinkedList() { LinkedList ll = new LinkedList<>(); ll.addAll(Countries.names(25)); print(ll); // Treat it like a stack, pushing: ll.addFirst("one"); ll.addFirst("two"); print(ll); // Like "peeking" at the top of a stack: print(ll.getFirst()); // Like popping a stack: print(ll.removeFirst()); print(ll.removeFirst()); // Treat it like a queue, pulling elements // off the tail end: print(ll.removeLast()); print(ll); } public static void main(String[] args) { // Make and fill a new list each time: basicTest( new LinkedList<>(Countries.names(25))); basicTest( new ArrayList<>(Countries.names(25))); iterMotion( new LinkedList<>(Countries.names(25))); iterMotion( new ArrayList<>(Countries.names(25))); iterManipulation( new LinkedList<>(Countries.names(25))); iterManipulation( new ArrayList<>(Countries.names(25))); testVisual( new LinkedList<>(Countries.names(25))); testLinkedList(); } } /* (Execute to see output) *///:~