java_集合框架基础总结

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通过对集合框架的学习，一下实例是对集合框架基础总结

import java.util.*;

class Collection
{
public static void main(String[] args)
{
  TreeSet hs = new TreeSet(new mycomparetor());//传入比较器

  hs.add(new person("java05",25));
  hs.add(new person("java03",23));
  hs.add(new person("java08",21));
  hs.add(new person("java07",24));

  Iterator it = hs.iterator();
  while(it.hasNext())
  {
   person p = (person)it.next();
   System.out.println(p.getname()+"::"+p.getage());
  }
}
}

class person implements Comparable
{
String name;
int age;
person(String name,int age)
{
  this.age=age;
  this.name=name;
}
public String getname()
{
  return name;
}
public int getage()
{
  return age;
}
//复写hashCode()方法
public int hashCode()
{
  return name.hashCode()+age*3;
}
//复写equals方法
public boolean equals(Object obj)
{
  if(!(obj instanceof person))
   throw new ClassCastException("类型错误");
  person p = (person)obj;
  if(this.age>p.age)
   return true;
  if(this.age==p.age)
  {
   return this.name.equals(p.name);
  }
  return false;
}
//复写compareTo()方法
public int compareTo(Object obj)
{
  if(!(obj instanceof person))
   throw new ClassCastException("类型错误");
  person p = (person)obj;
  int num = this.age-p.age ;
  if(num>0)
   return 1;
  if(num==0)
  {
   return this.name.compareTo(p.name);
  }
  return -1;
}
}
//自定义比较器
class mycomparetor implements Comparator<person>
{
public int compare(person p1,person p2)
{
  int num = p1.getname().compareTo(p2.getname());
  if(num==0)
   return new Integer(p1.getage()).compareTo(new Integer(p2.getage()));
  return num;
}
}

/*
1.HashSet,HashMap集合通过复写hashCode()与equals()方法来控制元素的唯一性
2.TreeSet,TreeMap集合通过实现Comparable接口，复写compareTo()方法来控制元素的唯一性
3.自定义比较器通过实现Comparator接口，复写compare()方法

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