第110集：容器SetHashSet基本用法源码分析

1. HashSet是最常用的set接口的实现类，它的底层实现是HashMap.

2. HashSet的特点是:无序，不可重复，添加重复元素会覆盖。【所以HashSet类没有get（int index）方法】

3. 常用方法：

   1. add

   2. remove

   3. size

   4. contains

package com.collection;import java.util.HashSet;import java.util.Set;public class TestSet {    public static void main(String[] args){        Set a = new HashSet();        a.add("aaa");        a.add("bbb");        a.add(new String("aaa"));//相同内容的元素是加不进set的        System.out.println(a.size());        a.remove("bbb");        System.out.println(a.size());        System.out.println(a.contains("aaa"));    }}

第111集：容器自定义实现HashSet

1. HashSet能够实现不重复，是因为利用了map的key不可重复的特性。

package com.collection;import java.util.HashMap;/** * @author wangtao * 自定义自己的HashSet */public class SxtHashSet {    HashMap map;    final Object PRESENT = new Object();         public SxtHashSet(){        map = new HashMap();    }        public void add(Object o){        map.put(o, PRESENT);    }        public int size(){        return map.size();    }        public static void main(String[] args){        SxtHashSet a = new SxtHashSet();        a.add("aaa");        a.add("bbb");        a.add("aaa");        System.out.println(a.size());        }    }

第112集：容器数据存储综合练习javabean的介绍

1. Javabean是指里面只有属性、set方法与get方法的类。

2. 代码所示方法是一种用对象封装数据的方法

package test112;import java.text.DateFormat;import java.text.ParseException;import java.text.SimpleDateFormat;import java.util.ArrayList;import java.util.Date;import java.util.List;public class Employee {    private int Id;    private String name;    private int salary;    private String company;    private Date date;        public Employee(int Id,String name,int salary,String company,String date){        this.Id = Id;        this.name = name;        this.salary = salary;        this.company = company;                DateFormat format = new SimpleDateFormat("yyyy-MM");        try {            this.date = format.parse(date);        } catch (ParseException e) {            e.printStackTrace();        }            }            public void setId(int Id){        this.Id = Id;    }        public int getId(){        return Id;    }        public void setName(String name){        this.name = name;    }    public String getName(){        return name;    }        public void setSalary(int Salary){        this.salary = Salary;    }        public int getSalary(){        return salary;    }        public void setCompany(){        this.company = company;    }        public String getCompany(){        return company;    }        public void setDate(Date date){        this.date = date;    }        public Date getDate(){        return date;    }        public static void main(String[] args){        Employee a = new Employee(0301,"高琪",3000,"项目部","2007-10");        Employee b = new Employee(0302,"马士兵",3200,"项目部","2005-10");        Employee c = new Employee(0303,"裴新",3300,"项目部","2006-10");                List
    
      list = new ArrayList
     
      ();        list.add(a);        list.add(b);        list.add(c);                for(int i=0;i
     
    

第113集：容器数据存储综合练习map保存表记录

1. 用Map接口保存数据也是一种常用的方法。【对比112集来看本集】

package test112_113;import java.util.ArrayList;import java.util.HashMap;import java.util.List;import java.util.Map;public class Employee_1 {    public static void main(String[] args){        Map map = new HashMap();        map.put("id", "0301");        map.put("name", "高琪");        map.put("salary", "3050");        map.put("company", "项目部");        map.put("Date", "2007-10");                Map map2 = new HashMap();        map2.put("id", "0302");        map2.put("name", "马士兵");        map2.put("salary", "3050");        map2.put("company", "项目部");        map2.put("Date", "2007-10");                Map map3 = new HashMap();        map3.put("id", "0303");        map3.put("name", "裴新");        map3.put("salary", "3050");        map3.put("company", "项目部");        map3.put("Date", "2007-10");                List