avoiding a recursive deadlock

[Chris IT-C]

consider this example:
1 public class Man {
2 private Woman wife;
3
4 public void setSpoose(Woman newWife) {
5 wife = newWife;
6 newSpoose.setWife(this);
7 }
8 }
9 public class Woman {
10 private Man husband;
11
12 public void setSpoose(Man newHusband) {
13 husband = newHusband;
14 newSpoose.setSpoose(this);
15 }
16}
my problem consist in that I want the setSpoose-method in the class Man to call the setSpoose-method in the woman class, wich call the method in the man class and so on. How to avoid this??
regards
Christian

[Chris IT-C]

line 14 ofcause reads newHusband.setSpoose(this);

Christian

[Jane Griscti]

Hi Chris,

Please read the JavaRanch Name Policy and re-register using a name that complies with the rules.

Thanks for your cooperation.

------------------
Jane Griscti
Sun Certified Programmer for the Java� 2 Platform
[This message has been edited by shailesh sonavadekar (edited June 24, 2001).]

[Christian Staermose]

See? name changed...so if anyone could advice on my problem...,please
Regards
Christian

[Christian Staermose]

To recap:
1 public class Man {
2 private Woman wife;
3
4 public void setSpoose(Woman newWife) {
5 wife = newWife;
6 newWife.setSpoose(this);
7 }
8 }
9 public class Woman {
10 private Man husband;
11
12 public void setSpoose(Man newHusband) {
13 husband = newHusband;
14 newHusband.setSpoose(this);
15 }
16}
my problem consist in that I want the setSpoose-method in the class Man to call the setSpoose-method in the woman class, wich call the method in the man class and so on. How to avoid this??
regards
Christian

[Carl Trusiak]

In any situation, you need to set a stop reason to avoid infinate recursion. Your example lends itself to the rule (in most societies) that one man can only have one wife and one women can only have one husband. adding a test to ensure husband or wife is not null sould satisfy this rule.

public class Man {
   private Woman wife;
   public void setSpoose(Woman newWife)  {
     if(wife == null && (!newWife.isMarried()| | newWife.isHusband(this)))
     {
         wife = newWife;
         newWife.setSpoose(this);
     }
   }
   public boolean isMarried()
   {
      return (wife != null);
   }
   public boolean isWife(Women lady)
   {
      return (wife == lady);
   }
 }
 public class Woman  {
  private Man husband;
  
  public void setSpoose(Man newHusband)  {
    if(husband == null && (!newHusband.isMarried() | | newHusband.isWife(this)))
    {
        husband = newHusband;
        newHusband.setSpoose(this);
    } 
  }
   public boolean isMarried()
   {
      return (husband != null);
   }
   public boolean isHusband(Man man) 
   {
      return (husband == man);
   }
}

Since husband sets the wife (or wife sets the husband first, you can allow the set if the other already declared you as their spouse.
In other societies, you can create a wife[] and/or a husband[] and iterate through it to see if that man or women already exists in the array and exit if it does.

------------------
Hope This Helps
Carl Trusiak, SCJP2
[This message has been edited by Carl Trusiak (edited June 24, 2001).]

[Christian Staermose]

Thanks Carl. That solves it. I will be adding a divorse function, so people can change spoose
Thanks
Christian

[Jim Yingst]

I know this won't really affect the execution of your program at all, but I feel compelled to point out that the word you're looking for is "spouse", not "spoose".