【Java】Map集合的几种遍历方式

public class Test1 {
public static void main(String[] args) {
// 1.定义HashMap集合,键为Student对象,值为String类型的对象,表示地址
HashMap<Student, String> map = new HashMap<>();
map.put(new Student("张三", 20, 15), "北京");
map.put(new Student("李四", 20,20), "南京");
map.put(new Student("王五", 20,45), "上海");
map.put(new Student("赵六", 20,56), "广州");
map.put(new Student("孙七", 20,78), "深圳");
//遍历方式一：增强for循环（entry）
for(Map.Entry<Student, String> entry :map.entrySet()){
System.out.println(entry.getKey()+""+entry.getValue());
}
//遍历方式二：增强for循环（keySet）
System.out.println("--------------------------------------------");
for(Student student : map.keySet()){
String address = map.get(student);
System.out.println(student+"::"+address);

}
//遍历集合方式三、迭代器
System.out.println("---------------------------------");
Set<Map.Entry<Student,String>> set = map.entrySet();
Iterator<Map.Entry<Student, String>> it = set.iterator();
while(it.hasNext()){
Map.Entry<Student,String> entry = it.next();
System.out.println(entry.getKey() + "::" + entry.getValue());

}
// 遍历方式四:迭代器(通过keySet())
System.out.println("-----------------------------------------");
Set<Student> keySet = map.keySet();
Iterator<Student> it2 =keySet.iterator();
while(it2.hasNext()){
Student student = it2.next();
String address = map.get(student);
System.out.println(student +"::"+address);
}
}