先来一个map集合
Map<String,Object> map = new HashMap<String,Object>();
Student student = new Student("stu01","张三","男");
Teacher teacher = new Teacher("tea01","王伟","女");
map.put("student", student);
map.put("teacher", teacher);
//第一种:通过keySet()遍历所有的健 原理是返回key组成的Set集合,再通过key获取键值对
Set key = map.keySet();
for (Object k : key) {
System.out.println(k);//结果:student teacher
}
for (String k : map.keySet()) {
System.out.println("key为:"+k+"----"+"value为:"+map.get(k));
}
//第二种:通过values()遍历所有的值,但是不能遍历key
for (Object value : map.values()) {
System.out.println(value);
}
//第三种:通过entrySet()遍历所有的健和值
for (Map.Entry<String, Object> m : map.entrySet()) {
System.out.println("key--->"+m.getKey()+"---"+"value--->"+m.getValue());
}
//第四种:通过entrySet()使用(迭代器)遍历所有的健和值
Iterator<Map.Entry<String, Object>> it = map.entrySet().iterator();
while(it.hasNext()){//是否有下一个
Map.Entry<String, Object> entry = it.next();
System.out.println("key--->"+entry.getKey()+"---"+"value--->"+entry.getValue());
}