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Lists.java
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126 lines (117 loc) · 3.71 KB
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package thinkinginjava.containers;
// Things you can do with Lists.
import java.util.*;
import thinkinginjava.util.Countries;
import static thinkinginjava.util.Print.*;
public class Lists {
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(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<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 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<String> a) {
print(a);
List<String> b = Countries.names(25);
print("b = " + b);
a.addAll(b);
a.addAll(b);
print(a);
// Insert, remove, and replace elements
// using a ListIterator:
ListIterator<String> 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<String> ll = new LinkedList<String>();
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<String>(Countries.names(25)));
basicTest(new ArrayList<String>(Countries.names(25)));
iterMotion(new LinkedList<String>(Countries.names(25)));
iterMotion(new ArrayList<String>(Countries.names(25)));
iterManipulation(new LinkedList<String>(Countries.names(25)));
iterManipulation(new ArrayList<String>(Countries.names(25)));
testVisual(new LinkedList<String>(Countries.names(25)));
testLinkedList();
}
} /* (Execute to see output) */// :~