集合框架——HashMap练习

/*每一个学生都有对应的归属地。学生Student，地址String。学生属性：姓名，年龄。注意：姓名和年龄相同的视为同一个学生。保证学生的唯一性。1，描述学生。2，定义map容器。将学生作为键，地址作为值。存入。3，获取map集合中的元素。*/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("lisi1",21),"tianjin");hm.put(new Student("lisi2",22),"shanghai");hm.put(new Student("lisi3",23),"nanjing");hm.put(new Student("lisi4",24),"wuhan");//第一种取出方式 keySetSet<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);}//第二种取出方式 entrySetSet<Map.Entry<Student,String>> entrySet = hm.entrySet();Iterator<Map.Entry<Student,String>> iter = entrySet.iterator();while(iter.hasNext()){Map.Entry<Student,String> me = iter.next();Student stu = me.getKey();String addr = me.getValue();System.out.println(stu+"........."+addr);}}}