java 集合框架

collection

 ----- LIst

---ArrayList

---LinkedList

---Vector

------Set 

----HashSet

----TreeSet

ArrayList 的基本用法

import java.util.*;class ArrayListDemo{public static void main(String[] args){ArrayList al = new ArrayList();al.add("haha");al.add("hello list");/*Iterator it = al.iterator();while(it.hasNext()) {System.out.println(it.next());}*///for 循环节省内存；for(Iterator it = al.iterator();it.hasNext();){System.out.println(it.next());}//ListIterator 接口对象比 iterator 对象具有更多的方法；但是只有list 对象有；ListIterator all = al.listIterator();while(all.hasNext()){Object obj = all.next();if(obj.equals("haha")){all.set("fasfdsaf");}}print(al);}public static void print(Object obj){System.out.println(obj);}}

LinkedList 的基本用法

//添加一个person 对象中 并且 除去重复的import java.util.*;class Person{private int age;private String name;Person(int age, String name){this.age = age;this.name = name;}public int sayAge(){return age;}public String sayName(){return name;}public boolean equals(Object obj){if(!(obj instanceof Person)){return false;}Person p = (Person) obj;return p.name == name && p.age == age;}}class linkListDemo{public static void main(String[] args){ArrayList al = new ArrayList();al.add(new Person(12,"tang"));al.add(new Person(12,"tang"));al.add(new Person(13,"wang"));al = singleElement(al);Iterator it = al.iterator();while(it.hasNext()){Person p = (Person) it.next();sop(p.sayName()+"----"+p.sayAge());}}public static void sop(Object obj){System.out.println(obj);}public static ArrayList singleElement(ArrayList al){ArrayList newal = new ArrayList();Iterator it = al.iterator();while(it.hasNext()){Object obj = it.next();if (!newal.contains(obj)) {newal.add(obj);}}return newal;}}

vector的基本用法

import java.util.*;class VectorDemo{public static void main(String[] args){Vector vc = new Vector();vc.add("val1");vc.add("val2");//其实和迭代器一样；Enumeration enums = vc.elements();while(enums.hasMoreElements()) {System.out.println(enums.nextElement());}}}

HashSet的基本用法

import java.util.*;class Person{private int age;private String name;Person(int age, String name){this.age = age;this.name = name;}public int getAge(){return this.age;}public String getName(){return this.name;}public int hashCode(){System.out.println(this.name+"----hashCode");return this.name.hashCode()+this.age*37;}public boolean equals(Object obj){if(!(obj instanceof Person)){return false;}System.out.println(this.name+"----equals");Person p = (Person) obj;return this.name.equals(p.getName()) && this.age == p.getAge();}}class HashSetTest{public static void main(String[] args){HashSet hs = new HashSet();hs.add(new Person(11,"a1"));hs.add(new Person(12,"a2"));hs.add(new Person(13,"a3"));hs.add(new Person(13,"a3"));Iterator it = hs.iterator();while(it.hasNext()){Person p = (Person) it.next();sop(p.getName()+"---"+p.getAge());}}public static void sop(Object obj){System.out.println(obj);}}

TreeSet的基本用法

import java.util.*;import java.lang.*;class Person implements Comparable{public int age;public String name;Person(int age, String name){this.age = age;this.name = name;}public int compareTo(Object obj){if(!(obj instanceof Person)){throw new RuntimeException("非 Person 对象");}Person p = (Person) obj;if(this.age > p.age) {return 1;}if(this.age == p.age){if(this.name.hashCode() > p.name.hashCode()){return 1;}if(this.name.hashCode() < p.name.hashCode()){return -1;}if(this.name.hashCode() == p.name.hashCode()){return 0;}}if(this.age < p.age){return -1;}return 0;}public int getAge(){return this.age;}public String getName(){return this.name;}}class TreeSetDemo{public static void main(String[] args){TreeSet ts = new TreeSet();ts.add(new Person(13,"a3"));ts.add(new Person(12,"a2"));ts.add(new Person(11,"a1"));ts.add(new Person(11,"a5"));Iterator it = ts.iterator();while(it.hasNext()){Person p = (Person) it.next();sop(p.getName()+"---"+p.getAge());}}public static void sop(Object obj){System.out.println(obj);}}