java新手笔记31 集合实现类
Person类：
package com.yfs.javase;
import java.util.Date;
public class Person implements Comparable {
private String name;
private int age;
private char sex;
public static Date date = new Date();
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + age;
result = prime * result + ((name == null) ? 0 : name.hashCode());
result = prime * result + sex;
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
Person other = (Person) obj;
if (age != other.age)
return false;
if (name == null) {
if (other.name != null)
return false;
} else if (!name.equals(other.name))
return false;
if (sex != other.sex)
return false;
return true;
}
public Person() {
}
public Person (String n) {
this.name = n;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public char getSex() {
return sex;
}
public void setSex(char sex) {
this.sex = sex;
}
@Override
public String toString() {
return "Person [name=" + name + ", age=" + age + ", sex=" + sex + "]";
}
public Person(String name, int age, char sex) {
super();
this.name = name;
this.age = age;
this.sex = sex;
}
@Override
public int compareTo(Object o) {
Person p = (Person)o;
return p.age - age;
}
}
1.set
package com.yfs.javase;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
public class Demo1 {
/**
* Set
*/
public static void main(String[] args) {
// LinkedHashSet lSet = null;//增加 删除
// HashSet hSet = null;//查找
// TreeSet tSet = null;//排序
// useLinkedSet();
//useTreeSet();
useArrayList();
}
public static void useArrayList() {
ArrayList list = new ArrayList();//必须覆盖equals方法
Person p = new Person("张三",20,'男');
list.add(p);
list.add(new Person("李四",23,'女'));
list.add(new Person("王五",22,'男'));
list.add(new Person("王Z",21,'女'));
list.add(p);
System.out.println("是否有张三：" + list.contains(p));//指向同一对象
System.out.println("是否有张三：" + list.contains(new Person("张三",20,'男')));
System.out.println("元素：" + list);
}
public static void useTreeSet() {
TreeSet tSet = new TreeSet();
tSet.add("fff");
tSet.add("ccc");
tSet.add("aaa");
tSet.add("ddd");
tSet.add("aaa");
System.out.println("元素个数： " + tSet.size());
System.out.println("元素： " + tSet);
}
public static void useLinkedSet() {
LinkedHashSet lSet = new LinkedHashSet();
lSet.add("fff");
lSet.add("ccc");
lSet.add("aaa");
lSet.add("ddd");
lSet.add("aaa");
System.out.println("元素个数： " + lSet.size());
System.out.println("元素： " + lSet);
}
}
2.Mycompare类
package com.yfs.javase;
import java.util.Comparator;
//外部比较器
public class Mycompare implements Comparator {
@Override
public int compare(Object o1, Object o2) {
Person p1 = (Person)o1;
Person p2 = (Person)o2;
return p1.getAge() - p2.getAge();//使用年龄排序
}
}
使用比较器:
package com.yema.javase;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
public class Demo2 {
/**
* Set
*/
public static void main(String[] args) {
//useLinkedSet();
useTreeSet();
// useArrayList();
}
public static void useArrayList() {
ArrayList list = new ArrayList();//必须覆盖equals方法
Person p = new Person("张三",20,'男');
list.add(p);
list.add(new Person("李四",23,'女'));
list.add(new Person("王五",22,'男'));
list.add(new Person("王Z",21,'女'));
list.add(p);
System.out.println("是否有张三：" + list.contains(p));//指向同一对象
System.out.println("是否有张三：" + list.contains(new Person("张三",20,'男')));
System.out.println("元素：" + list);
}
public static void useTreeSet() {
// Mycompare com = new Mycompare();//使用比较器
// TreeSet tSet = new TreeSet(com);//必须覆盖hashcode equals方法
TreeSet tSet = new TreeSet();//必须覆盖hashcode equals方法
Person p = new Person("张三",20,'男');
tSet.add(p);
tSet.add(new Person("李四",23,'女'));
tSet.add(new Person("王五",22,'男'));
tSet.add(new Person("王Z",21,'女'));
tSet.add(p);
System.out.println("是否有张三：" + tSet.contains(p));//指向同一对象
System.out.println("是否有张三：" + tSet.contains(new Person("张三",20,'男')));
System.out.println("元素：" + tSet);
}
public static void useLinkedSet() {
LinkedHashSet lSet = new LinkedHashSet();//必须覆盖hashcode equals方法
Person p = new Person("张三",20,'男');
lSet.add(p);
lSet.add(new Person("李四",23,'女'));
lSet.add(new Person("王五",22,'男'));
lSet.add(new Person("王Z",21,'女'));
lSet.add(p);
System.out.println("是否有张三：" + lSet.contains(p));//指向同一对象
System.out.println("是否有张三：" + lSet.contains(new Person("张三",20,'男')));
System.out.println("元素：" + lSet);
}
}
3.泛型
package com.yfs.javase;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Random;
public class Demo3 {
/**
* 泛型
*/
public static void main(String[] args) {
// useArrayList();
useCollection();
}
private static void useCollection() {
// 指定集合放入对象类型
Collection<Person> col = new HashSet<Person>();
col.add(new Person("张三", 20, '男'));
col.add(new Person("李四", 23, '女'));
col.add(new Person("王五", 22, '男'));
col.add(new Person("王Z", 21, '女'));
// list.add(new Random()); 其他类型对象不能放入
System.out.println("元素：" + col);
// Person p = (Person)list.get(4);
// Object obj = list.get(4);
// 取值不考虑类型 迭代器泛型
Iterator<Person> it = col.iterator();
while (it.hasNext()) {
Person p = it.next();
System.out.println(p);
}
}
public static void useArrayList() {
// 指定集合放入对象类型
ArrayList<Person> list = new ArrayList<Person>();
list.add(new Person("张三", 20, '男'));
list.add(new Person("李四", 23, '女'));
list.add(new Person("王五", 22, '男'));
list.add(new Person("王Z", 21, '女'));
// list.add(new Random()); 其他类型对象不能放入
System.out.println("元素：" + list);
// Person p = (Person)list.get(4);
// Object obj = list.get(4);
Person p = list.get(2);// 取值不考虑类型
}
}
4.HashMap
package com.yfs.javase;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
public class MapDemo1 {
/**
* @param args
*/
public static void main(String[] args) {
Map map = new HashMap();
map.put(1, new Person());//put添加对象key value
map.put(2, new Random());
map.put("zhangsan", "1388888888");
map.put("lisi", "139999999");
map.put("zhangsan", "1300000000");
System.out.println("元素个数 ： " + map.size());
System.out.println("元素： " + map);
System.out.println(map.get(1));
System.out.println(map.get("lisi"));
System.out.println("是否有zhangsan key ：" + map.containsKey("zhangsan"));
System.out.println("是否有139999999号码：" + map.containsValue("139999999"));
}
}
5.Map（Iterator)实体、key的集合
package com.yfs.javase;
import java.util.Collection;
import java.util.Date;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class MapDemo2 {
/**
* @param args
*/
public static void main(String[] args) {
//useMap();
//useMapEntry();
//Date d = Person.date;
useKey();
}
public static void useMapEntry() {
Map<String,String> map = new HashMap<String,String>();
map.put("zhangsan", "1388888888");
map.put("lisi", "139999999");
map.put("zhang", "1300000000");
map.put("wangwu", "1311111111");
map.put("Tom", "1583333333333");
map.put("Jack", "133333333333");
Set<Map.Entry<String, String>> set = map.entrySet();//===================不同
for(Iterator<Map.Entry<String, String>> it = set.iterator(); it.hasNext();){
Map.Entry<String, String> entry = it.next();
String key = entry.getKey();
String value= entry.getValue();
System.out.println(key + " === > " + value);
}
}
public static void useKey() {
Map<String,String> map = new HashMap<String,String>();
map.put("zhangsan", "1388888888");
map.put("lisi", "139999999");
map.put("zhang", "1300000000");
map.put("wangwu", "1311111111");
map.put("Tom", "1583333333333");
map.put("Jack", "133333333333");
System.out.println("元素个数 ： " + map.size());
System.out.println("元素： " + map);
//所有key 集合
System.out.println("==========key + value 集合==========");
Set set = map.keySet();//========================================不同
for(Iterator<String> it = set.iterator(); it.hasNext();){
String key = it.next();//keyjihe
System.out.print(key + " +++ ");
String value = map.get(key);// mapjihe
System.out.print(value + "\n");
}
}
}
