HashMap存储自定义对象练习（两种取出方式）

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package Map;
import java.util.*;
import java.util.Map.Entry;
/*
* 要求：用HashMap存储自定义对象，并采用两种方法取出
* 思路：创建自定义对象（考虑到可能存储到其他类型的集合中，
*
在创建时需要复写hashCode,equals方法，实现Comparator接口）
*
使用KeySet，EntrySet取出元素；
* */
//实现的应该是Comparable，而不是Comparetor,
//后者是比较器通常用于在调用的类内没有比较方法或方法不符合要求时自定义比较器
//并将其作为参数传入集合来完成特定比较
public class HashMapTest {
public static void main(String[] args) {
HashMap<Student,String> hm = new HashMap<Student,String>();
hm.put(new Student("student1",21), "beijing");
hm.put(new Student("student2",22), "shanghai");
hm.put(new Student("student3",23), "anhui");
hm.put(new Student("student4",24), "anhui");
//取出
//KeySet取出
Set<Student> keySet = hm.keySet();
for(Iterator<Student> it = keySet.iterator();it.hasNext();) {
Student s = it.next();
System.out.println(s.getName()+"
"+s.getAge()+"
"+hm.get(s));
}
//EntrySet
Set<Entry<Student,String>> entrySet = hm.entrySet();
for(Iterator<Entry<Student,String>> iter = entrySet.iterator();iter.hasNext();)
{
Entry<Student,String> en = iter.next();
Student s = en.getKey();
String address = en.getValue();
System.out.println(s.getName()+"----"+s.getAge()+"-----"+address);
}
}
}

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class Student implements Comparable<Student>{
private String name;
private int age;
Student(String name,int age){
this.name = name;
this.age = age;
}
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 int compareTo(Student s) {
int num = new Integer(this.age).compareTo(new Integer(s.age));
if(num == 0) {
return this.name.compareTo(s.name);
}
return num;
}
public int hashCode(Object obj) {
return name.hashCode()+age*32;
}
public boolean equals(Object obj) {
if(!(obj instanceof Student))
throw new ClassCastException("传入的类类型异常");
Student s = (Student)obj;
if(this.age == s.age && this.name.equals(s.name))
return true;
return false;
}
}