java - 找不到符号 `asIterator()`

Question

我有一个文件，adapter/new/myAdapter.java

package adapter.new;
import adapter.old.Person;

import java.util.Enumeration;
import java.util.Iterator;

public class GroupAdapter implements Group {

    private adapter.old.Group oldgroup;

    public GroupAdapter(adapter.old.Group oldgroup) {
        this.oldgroup = oldgroup;
    }

    @Override
    public Iterable<Person> getPersons() {
      return new Iterable<Person>() {
        @Override
        public Iterator<Person> iterator() {
          return oldgroup.getPersons().asIterator();
        }
      };
    }
}

这是我的adapter/old/Group.java

package adapter.old;

import java.util.Enumeration;
import java.util.Vector;

public class Group {
  private String number;
  private String name;
  private Vector<Person> persons;

  public Group(String number, String name) {
    this.number = number;
    this.name = name
    persons = new Vector<>();
  }

  public Enumeration<Person> getPersons() {
    return persons.elements();
  }  
}

当我尝试编译这个时:

javac old/*.java new/*.java

我收到此错误:

new/GroupAdapter.java:41: error: cannot find symbol
          return oldgroup.getPersons().asIterator();
                                       ^
  symbol:   method asIterator()
  location: interface Enumeration<Person>
1 error

我做错了什么？我或多或少地遵循了教程，但我找不到哪里出错了。

Answer 1

java9 中的 Enumeration 类中添加了 asIterator 方法。检查您使用的 javac 版本。

Enumeration javadoc java 8

Enumeration javadoc java 9