麻烦大神帮忙看下for (Object object : a) { }的返回值有什么问题？

Question

public class Person{
private Long idCard;
pirvate String userName;
//一下是getter和setter方法
……
}
List list=new ArrayList();
Person p1=new Person();
p1.setIdCard(new Long(1001));
p1.setUserName(“terry”);
Person p2=new Person();
p2.setIdCard(new Long(1002));
p2.setUserName(“tom”);
list.add(p1);
list.add(p2);
for(《插入代码》){
System.out.println(person.getIdCard()+”:”+person.getUserName());
}

Answer 1

你应该将list该为泛型如：List<person> List=new ArrayList<person>();这样list的对象类型已经确定，循环时就可以for (person person:List) {System.out.println(person.getIdCard()+”:”+person.getUserName());}这和for (int i = 0; i < List.size(); i++) {person person=pList.get(i);System.out.println(person.getIdCard()+”:”+person.getUserName());}是一样的