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Commitba0882f

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committed
修改目录结构
1 parent0104f61 commitba0882f

7 files changed

+382
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lines changed

‎day17/Collection集合总结.txt‎

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1:Collection集合体系结构
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Collection
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|--List(元素有序,可重复)
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|--ArrayList
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底层数据结构是数组,查询快,增删慢
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线程不安全,效率高
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|--Vector
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底层数据结构是数组,查询快,增删慢
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线程安全,效率低
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|--LinkedList
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底层数据结构是链表,查询慢,增删快
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线程不安全,效率高
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|--Set(元素无序,唯一)
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|--HashSet
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底层数据结构是哈希表。
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保证元素的唯一性?
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依赖两个方法hashCode()和equals()。
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|--LinkedHashSet
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底层数据结构是哈希表和链表
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由哈希表保证元素唯一
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由链表保证元素有序
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|--TreeSet
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底层数据结构是二叉树(红黑树)
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保证元素的唯一性?
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根据比较的返回值是否是0
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保证元素的排序?
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自然排序
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比较器排序
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2:针对Collection,你准备使用谁?
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元素唯一吗?
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是:Set
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要排序吗?
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是:TreeSet
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否:HashSet
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不知道,就用HashSet
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否:List
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要安全吗?
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要:Vector(其实也不用,有更好的方式,后面讲)
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不要:ArrayList或者LinkedList
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查询多:ArrayList
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增删多:LinkedList
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不知道,就用ArrayList
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不知道,就用ArrayList
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3:集合中的数据结构问题
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ArrayXxx:底层数据结构是数组,查询快,增删慢
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LinkedXxx:底层数据结构是链表,查询慢,增删快
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HashXxx:底层数据结构是哈希表。依赖两个方法hashCode()和equals(),根据情况选择是否自动重写
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TreeXxx:底层数据结构是二叉树。有两种方案:自然排序,比较器排序。
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‎day17/day17总结.txt‎

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1����ϰ
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(1)��ȡ1-20֮��������10����Ҫ�����ظ�
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(2)����¼�������ݣ���0����������ȡ¼�������е����ֵ
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(3)Collection���ϵ�toString()����Դ��
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(4)��¼ע�᰸�����ϰ�
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2��Set����(����)
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(1)Set���ϵ��ص�
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����Ψһ
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(2)HashSet����(����)
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A:Ԫ��Ψһ
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B:��α�֤Ԫ��Ψһ��?
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HashSet���ϵĵײ����ݽṹ�ǹ�ϣ����
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��ϣ����֤Ԫ��Ψһ����������������hashCode()��equals()
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���裺
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a:�����ж϶���Ĺ�ϣֵ�Ƿ���ͬ
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b:�����ͬ����ֱ�����ӵ�����
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�����ͬ���ͼ���ִ��equals()���бȽ�
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c:�������false����ֱ�����ӵ�����
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�������true��˵��Ԫ���ظ��������ӡ�
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C:���õ���
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����HashXxx��ʽ�ļ��ϣ�Ҫ��ס��д�����������ɡ����ң������������ǿ����Զ����ɵ�
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(3)LinkedHashSet
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�ײ����ݽṹ�ǹ�ϣ����������
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�ɹ�ϣ����֤Ԫ�ص�Ψһ�ԡ�
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��������֤Ԫ�ص�����(�洢˳���ȡ��˳��һ��)
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(4)TreeSet����(����)
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�ײ����ݽṹ�Ǻ������ƽ�������
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A:Ԫ��Ψһ��������Ҫ������
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B:��α�֤Ԫ��Ψһ����?
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���ݱȽϵķ���ֵ�Ƿ���0���ж�
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C:��α�֤Ԫ���������?
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���ַ�ʽ
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a:��Ȼ����(Ԫ�ؾ߱��Ƚ���)
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��Ԫ����������ʵ��Comparable�ӿ�
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b:�Ƚ�������(���Ͼ߱��Ƚ���)
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�������϶����ʱ�򣬽���Comparator�ӿڵ�ʵ���������Ϊ�������
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(5)����
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A:HashSet����
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�洢�ַ���������
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�洢�Զ�����󲢱���(�������ij�Ա����ֵ��ͬ��Ϊͬһ��ֵ)
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B:TreeSet����
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�洢�ַ���������
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�洢�Զ�����󲢱���(�������ij�Ա����ֵ��ͬ��Ϊͬһ��ֵ,���������С��������)
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C:��ȡ1-20֮��������10����Ҫ�����ظ�
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D:����¼��5��ѧ�����󣬲����ֽܷ�������

‎day17/二叉树结构.bmp‎

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‎day17/要练习的代码.txt‎

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���ϵIJ������裺
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A:�������϶���
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B:����Ԫ�ض���
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C:��Ԫ�����ӵ�����
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D:��������
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���ϵı�����ʽ��
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Collection:������,��ǿfor
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|--List:��ͨfor
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|--Set:
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�ַ���(���� hello,world,java)
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�Զ������(ѧ����)
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class Student {
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private String name;
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private int age;
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public Student() {}
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public Student(String name,int age) {
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this.name = name;
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this.age = age;
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}
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public void setName(String name) {
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this.name = name;
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}
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public String getName() {
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return name;
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}
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public void setAge(int age) {
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this.age = age;
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}
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public int getAge() {
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return age;
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}
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}
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1��Collection
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A:�ַ���
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Collection<String> c = new ArrayList<String>();
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c.add("hello");
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c.add("world");
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c.add("java");
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Iterator<String> it = c.iterator();
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while(it.hasNext()) {
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String s = it.next();
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System.out.println(s);
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}
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for(String s : c) {
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System.out.println(s);
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}
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B:�Զ������
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Collection<Student> c = new ArrayList<Student>();
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Student s1 = new Student("������",50);
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Student s2 = new Student("����׿",40);
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Student s3 = new Student("�⾩",30);
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c.add(s1);
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c.add(s2);
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c.add(s3);
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Iterator<Student> it = c.iterator();
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while(it.hasNext()) {
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Student s = it.next();
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System.out.println(s.getName()+"---"+s.getAge());
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}
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for(Student s : c) {
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System.out.println(s.getName()+"---"+s.getAge());
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}
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2��List
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A:�ַ���
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List<String> list = new ArrayList<String>();
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list.add("hello");
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list.add("world");
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list.add("java");
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Iterator<String> it = list.iterator();
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while(it.hasNext()) {
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String s = it.next();
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System.out.println(s);
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}
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for(String s : list) {
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System.out.println(s);
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}
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for(int x=0; x<list.size(); x++) {
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String s = list.get(x);
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System.out.println(s);
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}
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B:�Զ������
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List<Student> list = new ArrayList<Student>();
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Student s1 = new Student("������",50);
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Student s2 = new Student("����׿",40);
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Student s3 = new Student("�⾩",30);
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list.add(s1);
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list.add(s2);
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list.add(s3);
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Iterator<Student> it = list.iterator();
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while(it.hasNext()) {
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Student s = it.next();
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System.out.println(s.getName()+"---"+s.getAge());
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}
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for(Student s : list) {
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System.out.println(s.getName()+"---"+s.getAge());
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}
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for(int x=0; x<list.size(); x++) {
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Student s = list.get(x);
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System.out.println(s.getName()+"---"+s.getAge());
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}
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3��ArrayList(���� �Լ�����)
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A:�ַ���
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ArrayList<String> array = new ArrayList<String>();
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array.add("java");
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array.add("hello");
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array.add("world");
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//��ͨforѭ��
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for(int i =0; i<array.size(); i++) {
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String s = array.get(i);
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System.out.println(s);
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}
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//��ǿfor
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for(String s : array) {
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System.out.println(s);
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}
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//������
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Iterator<String> it = array.iterator();
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while(it.hasNext()) {
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String s = it.next();
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System.out.println(s);
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}
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B:�Զ������
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ArrayList<Student> array = new ArrayList<Student>();
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Student s1 = new Student("laozi",1000);
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Student s2 = new Student("kongzi",100);
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Student s3 = new Student("zhuangzi",10);
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array.add(s1);
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array.add(s2);
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array.add(s3);
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//��ͨforѭ��
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for (int i = 0; i<array.size(); i++) {
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Student s = array.get(i);
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System.out.println(s.getName()+"---"+s.getAge());
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}
171+
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//��ǿforѭ��
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for (Student s : array) {
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System.out.println(s.getName()+"---"+s.getAge());
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}
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//������ѭ��
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for(Iterator<Student> it = array.iterator(); it.hasNext();) {
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Student s = it.next();
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System.out.println(s.getName()+"---"+s.getAge());
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}
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183+
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4��Vector(�Լ�����)
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A:�ַ���
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Vector<String> vector = new Voctor<String>();
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vector.add("java");
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vector.add("hello");
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vector.add("world");
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//��ͨforѭ��
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for(int i =0; i<vector.size(); i++) {
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String s = vector.get(i);
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System.out.println(s);
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}
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//��ǿfor
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for(String s : vector) {
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System.out.println(s);
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}
202+
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//������
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Iterator<String> it = vector.iterator();
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while(it.hasNext()) {
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String s = it.next();
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System.out.println(s);
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}
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B:�Զ������
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vectorList<Student> array = new vectorList<Student>();
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Student s1 = new Student("laozi",1000);
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Student s2 = new Student("kongzi",100);
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Student s3 = new Student("zhuangzi",10);
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vector.add(s1);
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vector.add(s2);
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vector.add(s3);
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//��ͨforѭ��
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for (int i = 0; i<vector.size(); i++) {
222+
Student s = vector.get(i);
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System.out.println(s.getName()+"---"+s.getAge());
224+
}
225+
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//��ǿforѭ��
227+
for (Student s : vector) {
228+
System.out.println(s.getName()+"---"+s.getAge());
229+
}
230+
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//������ѭ��
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for(Iterator<Student> it = vector.iterator(); it.hasNext();) {
233+
Student s = it.next();
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System.out.println(s.getName()+"---"+s.getAge());
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}
236+
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5��LinkedList(���� �Լ�����)
238+
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6��Set
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A:�ַ���
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Set<String> set = new HashSet<String>();
242+
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set.add("hello");
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set.add("world");
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set.add("java");
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Iterator<String> it = set.iterator();
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while(it.hasNext()) {
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String s = it.next();
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System.out.println(s);
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}
252+
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for(String s : set) {
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System.out.println(s);
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}
256+
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B:�Զ������
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Set<Student> set = new HashSet<Student>();
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Student s1 = new Student("������",50);
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Student s2 = new Student("����׿",40);
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Student s3 = new Student("�⾩",30);
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set.add(s1);
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set.add(s2);
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set.add(s3);
267+
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Iterator<Student> it = set.iterator();
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while(it.hasNext()) {
270+
Student s = it.next();
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System.out.println(s.getName()+"---"+s.getAge());
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}
273+
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for(Student s : set) {
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System.out.println(s.getName()+"---"+s.getAge());
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}
277+
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7��HashSet(���� �Լ�����)
279+
�洢�Զ�������ʱ�������Ա����ֵ��ͬ�����Ǿ���Ϊ��ͬһ��Ԫ�ء�
280+
281+
8��TreeSet(���� �Լ�����)
282+
�洢�Զ�������ʱ�������Ա����ֵ��ͬ�����Ǿ���Ϊ��ͬһ��Ԫ�ء�
283+
���ȸ��������С������������ڸ��������ij�������

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