- import java.util.*;
- class Student implements Comparable<Student>
- {
- private String name;
- private int age;
- Student(String name,int age)
- {
- this.name = name;
- 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()
- {
- return name.hashCode() + age*34;
- }
- public boolean equals(Object obj)
- {
- if(!(obj instanceof Student))
- throw new ClassCastException("类型不匹配");
- Student s = (Student)obj;
- return this.name.equals(s.name) && this.age == s.age;
- }
- public String getName()
- {
- return name;
- }
- public int getAge()
- {
- return age;
- }
- public String toString()
- {
- return name + ":" +age;
- }
- }
- class MapTest
- {
- public static void main(String[] args)
- {
- HashMap<Student,String> hm = new HashMap<Student,String>();
- hm.put(new Student("lisi1",21),"beijing");
- hm.put(new Student("lisi2",22),"shanghai");
- hm.put(new Student("lisi3",23),"nanjing");
- hm.put(new Student("lisi4",24),"wuhan");
- Set<Student> keySet = hm.keySet();
- Iterator<Student> it = keySet.iterator();
- while(it.hasNext())
- {
- Student stu = it.next();
- String addr = hm.get(stu);
- System.out.println(stu + "...." +addr);
- }
- Set<Map.Entry<Student,String>> entrySet = hm.entrySet();
- Iterator<Map.Entry<Student,String>> it1 = entrySet.iterator();
-
- while(it1.hasNext())
- {
- Map.Entry<Student,String> me = it1.next();
复制代码 //68行这里为啥不写泛型<Student,String>也不会有JVM的友好提示呢
- System.out.println(me.getKey()+".."+me.getValue());
- }
- }
- }
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