Equals() method help

I need to write an equals() method for the teams class that is consistent with the provided hashcode method

HashCode method

 public int hashCode()
   {
      return开发者_Go百科 this.getPro().hashCode() 
             + this.getTeam().hashCode(); 
   }

My equals method, but wont work

public boolean equals(Object obj)
   {
     ClassName pro = (ClassName) obj;
     return (this.getPro().hashCode() == pro.getPro());
             (this.getTeam().hashCode() == pro.getTeam());
   }

Any help would be good

Here you compare an hashcode (an int) to an object. Plus there is a semicolon in the middle of your statement.

You should try this instead :

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

    MyClass myClass = (MyClass) o;

    if (!pro.equals(myClass.pro)) return false;
    if (!team.equals(myClass.team)) return false;

    return true;
}

Here you compare the content of objects.

After @Bart K. comment here is the way to write your equals() method if team or pro are nullable :

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

    MyClass myClass = (MyClass) o;

    if (pro != null ? !pro.equals(myClass.pro) : myClass.pro != null) return false;
    if (team != null ? !team.equals(myClass.team) : myClass.team != null) return false;

    return true;
}

Resources :

• Javadoc - Object.equals() and Object.hashCode()

On the same topic :

• Overriding equals and hashCode in Java
• How to ensure hashCode() is consistent with equals()?
• How to implement hashCode and equals method

1. The hash of two objects being equal does not mean the two objects are equal.
2. To check if two conditions are both satisfied, use &&.

Thus,

public boolean equals(Object obj)
   {
     ClassName pro = (ClassName) obj;
     return this.getPro() == pro.getPro() && this.getTeam() == pro.getTeam();
   }

Still, your hashCode() will not generate good hash, and equals() will fail in many cases (e.g. comparing with a non-ClassName or null). See Overriding equals and hashCode in Java for how to implement them correctly. Assuming no derived class, try

@Override public boolean equals(Object obj) {
   if (obj == this) return true;
   if (!(obj instanceof ClassName)) return false;
   ClassName pro = (ClassName)obj;
   <sometype> thisPro = getPro();
   if (thisPro == null || !thisPro.equals(pro.getPro()) return false;
   <sometype> thisTeam = getTeam();
   if (thisTeam == null || !thisTeam.equals(pro.getTeam()) return false;
   return true;
}