Question

当人1成为人3的伴侣的时候，人2不再有作为伴侣的人1，并且人4不再有作为伴侣的人3。我该怎么解决这个问题？

public class Person {

    private String name;
    private Person partner;

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

    public void setPartner(Person partner){
        this.partner = partner;
        partner.partner = this; 
    }

    public static void main(String[] args) {

        Person one = new Person("1");           
        Person two = new Person("2");
        Person three = new Person("3");
        Person four = new Person("4");

        one.setPartner(two);
        three.setPartner(four);

        one.setPartner(three);

        //Person two is still partner with person 1
        //and person four is still partner with person 3 
   }

Answer 1

public void setPartner(Partner b) {
  // Special case, otherwise we'll have troubles
  // when this.partner is already b.
  if (this.partner == b) return;

  if (this.partner != null) {
    this.partner.partner = null;
  }

  this.partner = b;

  // Make sure that the new partner has the right partner.
  // This will make sure the original b.partner has its
  // partner field nullified.
  // Note that if we don't have the special case above,
  // this will be an infinite recursion.
  b.setPartner(this);
}

Answer 2

public void setPartner(Person partner){
    if (this.partner != null) {
        this.partner.partner = null; // Reset the partner of the old partner.
    }
    this.partner = partner;          // Assign new partner.
    this.partner.partner = this;     // Set the partner of the new partner.
}

Answer 3

我认为将此作为setPartner中的第一行应该有效：this.partner.partner = null;

当然，您必须检查this.partner是否为null。

Answer 4

将setPartner更改为：

public void setPartner(Person partner){
    if(this.partner != null)
        this.partner.partner = null;
    this.partner = partner;
    partner.partner = this; 
}

Answer 5

我建议您设置一个setRelationship方法，该方法会对当前setPartner采取Person行动，并对旧合作伙伴采取新的removePartner行动，如果不是空的。

新的setRelationship方法将会存在，以便不会混淆setPartner的作用 - 毫无疑问的程序员可能没有任何副作用。

Answer 6

class Person {

  String name;
  Partnership partnership;
  void setPartnership(Partnership p) {
    partnership=p;
  }
}
class Partnership {
  Person partner1;
  Person partner2;
  public setPartners(Person p1,Person p2) {
    p1.setPartnership(this);
    p2.setPartnership(this);
}

理想情况下，您需要一种方法来阻止从伙伴关系以外的任何地方调用setPartnership。

Answer 7

这是我的代码：

public void setPartner(Person partner) {
    if (this.partner != null)
       this.partner.partner = null;
    this.partner = partner;
    if (partner.partner != null)
       partner.partner.partner = null;
    partner.partner = this;
}

对象参考案例研究

7 个答案: