encapsulating of array

[dar]

Hi all,

I don't know how can I encapsulate array member in class.

SimpleClassArray{
  private JTextField teams[] = new JTextField[TEAM_COUNT];
  .....
  
  public JTextField[] getTeams(){
    return teams
  }
  
  public void setTeamAt(int i, String teamName){
    if(teamName != null){
      teams[i].setText(teamName);
    }
  }
}

It seems like the method setTeamAt is unneedful.
The method getTeams() is getter(it's right), but it can work like setter too(it's wrong).
It's possible

getTeams()[someIndex] = someValue;

I would disallow it, I don't know any trick to do it.


Is there any "nice" trick to do it?

Thanks.

[Ernest Friedman-Hill]

A fundamental rule of good Java programming is "don't return a reference to an array member unless you don't care what changes are made to it." Since it's rarely the case that you truly don't care, this rule can't be shortened to "Don't give out references to array members."

You could return a clone of the array,

public JTextField[] getTeams(){
    return (JTextField[]) teams.clone();
  }

or you could provide a read-only interface:

public int getNTeams() {
  return teams.length;
}
 
public JTextField getTeam(int i) {
  return teams[i];
}

Either of these solutions would let clients get access to the JTextFields but not modify the array.

[dar]

thanks, Ernest.
[ June 24, 2004: Message edited by: dajac chison ]