我可以让某人验证我的作品集以进行SCJP考试吗？
我一直在学习SCJP，现在是Oracle认证专业Java SE程序员考试。
我有一段困难的时光，围绕着所有不同的收藏品以及何时使用它们。 我也喜欢闪存卡。 所以我尝试创建一组基本相同的类，除了它们使用的是哪个集合。 我将不得不确定输出的结果以及每个集合的主要“特征”。
不幸的是我不相信自己。 我希望有人确认所有信息都是准确的或者是否有遗漏。 然后，经过一些反馈/更正之后，我认为对于试图理解Java集合的其他人来说，这将是一个很好的练习。
覆盖的集合有：HashMap，Hashtable，TreeMap，LinkedHashMap，HashSet，TreeSet，LinkedHashSet，ArrayList，Vector，LinkedList，PriorityQueue。
我也将所有文件分离出来，他们可以在这里下载：http://www.allgo.com/personal/MyCollections.zip
提前致谢
import java.util.*;
import java.lang.*;
class MyItem implements Comparable{
private String name;
MyItem(String n){ name = n; }
public String toString(){return name;}
public String getName(){return name;}
public boolean equals(Object obj){
if(this==obj) return true;
else if(obj==null) return false;
else if(getName() != ((MyItem)obj).getName()) return false;
else return true;
}
public int hashCode(){ return 5; }
public int compareTo(MyItem b){return b.getName().compareTo(getName());}
}
public class MyCollections{
public static void main(String[] args){
MyHashMap.main(args); System.out.println("HashMap: Hash=Unsorted, Unordered. Map=key/value pairn##n");
MyHashtable.main(args); System.out.println("Hashtable: Thread Safe. Hash=Unsorted, Unordered. Map=key/value pairn##n");
MyTreeMap.main(args); System.out.println("TreeMap: Tree=sorted. Map=key/value.n##n");
MyLinkedHashMap.main(args); System.out.println("LinkedHashMap: Linked=Maintains Insertion Order. Hash=unsorted, unordered. Map=key/value pair.n##n");
MyHashSet.main(args); System.out.println("HashSet: Hash=Unsorted, Unordered. Set=Unique. Define=equals/hashCoden##n");
MyTreeSet.main(args); System.out.println("TreeSet: Tree=Sorted. Set=Unique. Define=Comparable/Comparatorn##n");
MyLinkedHashSet.main(args); System.out.println("LinkedHashSet: Liniked=Maintains Insertion Order. Hash=Unsorted. Set=Unique. Define=equals/hashCoden##n");
MyArrayList.main(args); System.out.println("ArrayList: List=Queue. Maintains insertion order, Allowed duplicatesn##n");
MyVector.main(args); System.out.println("Vector: Thread Safe. ArrayList. Maintains Insertion Order, Allows duplicatesn##n");
MyLinkedList.main(args); System.out.println("LinkedList: Linked=Maintaines Insertion Order. List=Queue. Advanced ArrayList with more methods.n##n");
MyPriorityQueue.main(args); System.out.println("PriorityQueue: Define=Comparable/comparatorn##n");
}
}
class MyHashMap{
public static void main(String[] args){
HashMap c = new HashMap();
MyItem Eight = new MyItem("Eight");
c.put(5, new MyItem("Five")); c.put(1, new MyItem("One")); c.put(8, Eight); c.put(3, new MyItem("Three"));
c.put(4, new MyItem("Four")); c.put(1, new MyItem("1")); c.put(8, Eight); c.put(9, new MyItem("Nine"));
c.remove(3); c.put(7, new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyHashtable{
public static void main(String[] args){
Hashtable c = new Hashtable();
MyItem Eight = new MyItem("Eight");
c.put(5, new MyItem("Five")); c.put(1, new MyItem("One")); c.put(8, Eight); c.put(3, new MyItem("Three"));
c.put(4, new MyItem("Four")); c.put(1, new MyItem("1")); c.put(8, Eight); c.put(9, new MyItem("Nine"));
c.remove(3); c.put(7, new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyTreeMap{
public static void main(String[] args){
TreeMap c = new TreeMap();
MyItem Eight = new MyItem("Eight");
c.put(5, new MyItem("Five")); c.put(1, new MyItem("One")); c.put(8, Eight); c.put(3, new MyItem("Three"));
c.put(4, new MyItem("Four")); c.put(1, new MyItem("1")); c.put(8, Eight); c.put(9, new MyItem("Nine"));
c.remove(3); c.put(7, new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyLinkedHashMap{
public static void main(String[] args){
LinkedHashMap c = new LinkedHashMap();
MyItem Eight = new MyItem("Eight");
c.put(5, new MyItem("Five")); c.put(1, new MyItem("One")); c.put(8, Eight); c.put(3, new MyItem("Three"));
c.put(4, new MyItem("Four")); c.put(1, new MyItem("1")); c.put(8, Eight); c.put(9, new MyItem("Nine"));
c.remove(3); c.put(7, new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyHashSet{
public static void main(String[] args){
HashSet c = new HashSet();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyTreeSet{
public static void main(String[] args){
TreeSet c = new TreeSet();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(Eight); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyLinkedHashSet{
public static void main(String[] args){
LinkedHashSet c = new LinkedHashSet();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyArrayList{
public static void main(String[] args){
ArrayList c = new ArrayList();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyVector{
public static void main(String[] args){
Vector c = new Vector();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyLinkedList{
public static void main(String[] args){
LinkedList c = new LinkedList();
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
}
class MyPriorityQueue{
public static void main(String[] args){
PriorityQueue c = new PriorityQueue();
MyItem Eight = new MyItem("Eight");
c.offer(new MyItem("Five")); c.offer(new MyItem("One")); c.offer(Eight); c.offer(new MyItem("Three"));
c.offer(new MyItem("Four")); c.offer(new MyItem("One")); c.offer(Eight); c.offer(new MyItem("Nine"));
System.out.println(c.peek());
System.out.println(c.poll());
c.offer(new MyItem("Seven"));
System.out.println(c);//output?
}
}
对于初学者，你应该重构你的代码。 基本上，无论你用什么“复制粘贴”，都不要。
创建一个像这样的方法：
private static void fill(Collection c) {
MyItem Eight = new MyItem("Eight");
c.add(new MyItem("Five")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Three"));
c.add(new MyItem("Four")); c.add(new MyItem("One")); c.add(Eight); c.add(new MyItem("Nine"));
c.remove(3); c.add(new MyItem("Seven"));
System.out.println(c);//output?
}
然后，而不是你有的方法，做到这一点：
class MyVector{
public static void main(String[] args){
Vector c = new Vector();
fill(c);
}
}
并为所有的收藏品做到这一点。
接下来，为你的地图做一个类似的事情：
private static void fill(Map<?,?> map) {
MyItem Eight = new MyItem("Eight");
map.put(5, new MyItem("Five")); map.put(1, new MyItem("One")); map.put(8, Eight); map.put(3, new MyItem("Three"));
map.put(4, new MyItem("Four")); map.put(1, new MyItem("1")); map.put(8, Eight); map.put(9, new MyItem("Nine"));
map.remove(3); map.put(7, new MyItem("Seven"));
System.out.println(map);//output?
}
你的代码会缩小，易读，甚至有一天会变得可用。
链接地址: http://www.djcxy.com/p/66567.html上一篇: Can I have someone verify my collections for the SCJP Exam
下一篇: Java Applet