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");
		}
	}
}