We will review the following topics today,
package test; import java.util.Random; import java.util.*; public class Timer { public static void main(String[] args) { long start = System.nanoTime(); long stop = System.nanoTime(); System.out.println(stop - start); Random rand = new Random(232345); rand.nextInt(); List list = new LinkedList(); list.add(new Integer(0)); list.add(new Double(0)); list.add(new String("asdsad")); //System.out.println(sumList1(list)); List<Integer> intList = new LinkedList<Integer>(); intList.add(new Integer(10)); intList.add(new Integer(20)); intList.add(new Integer(30)); System.out.println(sumList2(intList)); List<Float> floatList = new LinkedList<Float>(); floatList.add(new Float(10.123)); floatList.add(new Float(20.123)); List<String> stringList = new LinkedList<String>(); stringList.add("abc"); stringList.add("abd"); stringList.add("acd"); System.out.println(maxList(intList)); System.out.println(maxList(stringList)); } static Double sumList1(List list) { Iterator iter = list.listIterator(); Double sum = new Double(0); while (iter.hasNext()) sum += (Double)iter.next(); return sum; } static Double sumList2(List < ? extends Number > list) { Iterator< ? extends Number > iter = list.listIterator(); Double sum = new Double(0); while (iter.hasNext()) sum = sum + iter.next().doubleValue(); return sum; } static < N extends Comparable <N> > N maxList(List <N> list) { Iterator iter = list.listIterator(); N maxVal = iter.next(); while (iter.hasNext()) { N curVal = iter.next(); if( curVal.compareTo(maxVal) > 0 ) maxVal = curVal; } return maxVal; } }
http://cs-people.bu.edu/tvashwin/cs112_spring08/lab02.html