如何遍历hashmap

STUDENT.JAVA

package test;


public class Student {


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;
}
String name;
int age;

public Student (int age,String name){
this.age=age;
this.name=name;
}


}

package test;

import java.util.HashMap;
import java.util.Map;


public class map {




public static void main(String[] args) {
Map<String ,Student>  aa =new HashMap<String,Student>();
Student stu1 = new Student(1,"MapTom");
Student stu2 = new Student(2,"MapJack");
Student stu3 = new Student(3,"MapKoby");
aa.put("1", stu1);
aa.put("2", stu2);
aa.put("3", stu3);


for (String bb : aa.keySet()) {


System.out.println(aa.get(bb).getName());

}



}

}

MapKoby
MapJack
MapTom

遍历map的三种方法：

public class Collection_Map {    public static void main(String[] args) {        Map<String, Student> hm = new HashMap<String,Student>();        Student stu1 = new Student(1,"MapTom");        Student stu2 = new Student(2,"MapJack");        Student stu3 = new Student(3,"MapKoby");        hm.put("1", stu1);        hm.put("2", stu2);        hm.put("3", stu3);        /*第一种  先将map对象转成set，然后再转为迭代器*/        Iterator<Entry<String, Student>> it = hm.entrySet().iterator();        while (it.hasNext()) {            //System.out.println(it.next().getKey());            System.out.println(it.next().getValue().getName());        }        /*第二种 先将map转为set类型的key值集合，然后转为迭代器*/        Iterator<String> it2 = hm.keySet().iterator();        while(it2.hasNext()){        /*  System.out.println(it2.next());*/            System.out.println(hm.get(it2.next()).getName());        }        /*第三种*/        for(Map.Entry<String, Student> entry : hm.entrySet()){            String key = entry.getKey();            String value = entry.getValue().getName();            System.out.println(value);        }        /*第四种*/        for(String key : hm.keySet()){            System.out.println(hm.get(key).getName());        }    }}