Question

我正在尝试使用给定的名称和性别创建一个新的Couple实例，并在addCouple方法中添加到couple的集合。我有另一个名为Couple的课程。在那个课程中，我有一个名字和性别的getter和Setters。我尝试使用批量操作列表：

List<Dating> list1 = new ArrayList<Dating>(this.addCouple);

但我得到一个错误“非静态变量，这不能从静态上下文中引用”。然后我尝试使用Collection.sort然后打印出列表。我收到了同样的错误消息。所以我相信我不知道如何使用this.addList。有人能告诉我如何使用它。我应该使用this.addList吗？提前致谢。

public class Dating
{

  private List<Male> maleList;
  private List<Female> femaleList; 


  public Dating()
  {

    super();
    maleList = new ArrayList<Single>();
    femaleList = new ArrayList<Single>();
  }


  public void lists()
  { 
   this.addList("Jack","Male",'m');
   this.addList("Mike","Male",'m'); 

   this.addList("Lynda","Female",'f'); 
   this.addList("Katie","Female",'f'); 
  }


   public static void addCouple (String aName, char aGender)
   {
      Collections.sort(this.addList);
      for (Couple group : this.addList)
      {
         System.out.println(" " + group.getName() + " " + group.getGender());
      }

   }

Answer 1

我认为你有比这更大的问题。男，女，单身？这些是Person类的属性，而不是类本身的属性。您的设计需要返工。

你需要人和夫妻课程。您还需要一个反映现实世界的模型。无论喜欢与否，你都可以拥有男性 - 男性和女性 - 女性伴侣。

我是这样写的。如您所见，List工作正常：

Gender.java：

public enum Gender
{
    MALE, FEMALE;
}

MaritalStatus.java：

public enum MaritalStatus
{
    SINGLE, MARRIED, DIVORCED, WIDOWED, SEPARATED;
}

Person.java：

import java.text.DateFormat;
import java.util.Date;

public class Person
{
    private String name;
    private Date birthdate;
    private Gender gender;
    private MaritalStatus maritalStatus;

    public Person(String name)
    {
        this(name, new Date(), Gender.MALE, MaritalStatus.SINGLE);
    }

    public Person(String name, Gender gender)
    {
        this(name, new Date(), gender, MaritalStatus.SINGLE);
    }

    public Person(String name, Date birthdate)
    {
        this(name, birthdate, Gender.MALE, MaritalStatus.SINGLE);
    }

    public Person(String name, Date birthdate, Gender gender)
    {
        this(name, birthdate, gender, MaritalStatus.SINGLE);
    }

    public Person(String name, Date birthdate, Gender gender, MaritalStatus maritalStatus)
    {
        if ((name == null) || (name.trim().length() == 0))
            throw new IllegalArgumentException("name cannot be blank or null");

        this.name = name;
        this.birthdate = ((birthdate == null) ? new Date() : new Date(birthdate.getTime()));
        this.gender = gender;
        this.maritalStatus = maritalStatus;
    }

    public String getName()
    {
        return name;
    }

    public Date getBirthdate()
    {
        return new Date(birthdate.getTime());
    }

    public Gender getGender()
    {
        return gender;
    }

    public MaritalStatus getMaritalStatus()
    {
        return maritalStatus;
    }

    @Override
    public boolean equals(Object o)
    {
        if (this == o)
        {
            return true;
        }
        if (o == null || getClass() != o.getClass())
        {
            return false;
        }

        Person person = (Person) o;

        if (!birthdate.equals(person.birthdate))
        {
            return false;
        }
        if (gender != person.gender)
        {
            return false;
        }
        if (maritalStatus != person.maritalStatus)
        {
            return false;
        }
        if (!name.equals(person.name))
        {
            return false;
        }

        return true;
    }

    @Override
    public int hashCode()
    {
        int result = name.hashCode();
        result = 31 * result + birthdate.hashCode();
        result = 31 * result + gender.hashCode();
        result = 31 * result + maritalStatus.hashCode();
        return result;
    }

    @Override
    public String toString()
    {
        return "Person{" +
               "name='" + name + '\'' +
               ", birthdate=" + DateFormat.getDateInstance(DateFormat.MEDIUM).format(birthdate) +
               ", gender=" + gender +
               ", maritalStatus=" + maritalStatus +
               '}';
    }
}

Couple.java：

public class Couple
{
    private Person ying;
    private Person yang;

    public Couple(Person ying, Person yang)
    {
        this.ying = ying;
        this.yang = yang;
    }

    public Person getYing()
    {
        return ying;
    }

    public Person getYang()
    {
        return yang;
    }

    @Override
    public String toString()
    {
        return "Couple{" +
               "ying=" + ying +
               ", yang=" + yang +
               '}';
    }
}

Dating.java：

import java.util.ArrayList;
import java.util.List;


public class Dating
{
    private List<Person> individuals = new ArrayList<Person>();
    private List<Couple> couples     = new ArrayList<Couple>();

    public static void main(String[] args)
    {
        Dating dating = new Dating();

        dating.addIndividual(new Person("Jack"));
        dating.addIndividual(new Person("Mike"));
        dating.addIndividual(new Person("Lydia", Gender.FEMALE));
        dating.addIndividual(new Person("Kate", Gender.FEMALE));

        System.out.println(dating);
    }

    public void addIndividual(Person p)
    {
        this.individuals.add(p);
    }

    public void removeIndividual(Person p)
    {
        this.individuals.remove(p);
    }

    public Person findIndividual(String name)
    {
        Person found = null;

        if (name != null)
        {
            for (Person p : this.individuals)
            {
                if (name.equals(p.getName()))
                {
                    found = p;
                    break;
                }
            }
        }

        return found;
    }

    @Override
    public String toString()
    {
        return "Dating{" +
               "individuals=" + individuals +
               ", couples=" + couples +
               '}';
    }
}

Answer 2

您的addCouple被声明为静态方法。静态方法没有this，因为它们不属于实例。他们属于一个班级。

Answer 3

您必须使您的成员保持静态，或者必须从您的函数中删除静态标志。粗略地说，你不能将静态与静态混合。

Answer 4

你最好创建一个“Person”类，它可能大致如下：

public class Person
{
    private String name;
    private boolean male; // or use an enum GENDER if you plan to do more than male/female

    public Person(String name, boolean male)
    {
        this.name = name;
        this.male = male;
    }

    // [...] getters and setters

    public String toString()
    {
            return name + " " + (male ? "male" : "female");
    }
}

并且，取决于你真正想做的事情......（更多信息会更好）

public class Dating
{
    private List<Person> persons;
    //[...] constructor

    public void addWhateverYouMeanWithCouple(String name, boolean male)
    {
        this.persons.add(new Person(name, male));
        System.out.println(persons);
    }
}

我真的不知道你在寻找什么，这是我能为你提供的唯一代码，不过我仍然认为这不是你想要的。

如果要对人员列表进行排序，您将在Comparable<Person>类中实现Person（请参阅Comparable JavaDoc）并提供一些逻辑来比较两个人（例如使用{{ 1}}）。

如果你真的想要“情侣”或对，请看HashMap。

列表问题 - Java

4 个答案: