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set a shared value

Posted on 2002-07-25
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Last Modified: 2010-03-31
Hi all

I need to set a value for useris and password to be shared by all classes.

the String user, password
is derived thru login.class

I have other classes that will need this 2 String later.

How can I put in a class so that I can retrieve it anytime I want??  to be input into another class?








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Question by:TLTEO
3 Comments
 
LVL 4

Accepted Solution

by:
kylar earned 200 total points
ID: 7178047
Create a class like this:

public class IDHolder extends Object{
    private String m_userName = null;
    private String m_password = null;
    private IDHolder m_instance = null;
    private IDHolder(){

    }
    public static IDHolder getInstance(){
      if(null == m_instance)
          m_instance = new IDHolder();

       return m_instance;
    }

    public String getUserName(){ return m_userName;}
    public void setUserName(String newName){
        m_userName = newName;
    }
    public void setPassword(String newPass){
        m_password = newPass;

    }
    public String getPassword(){ return m_password;}

}


This is called a Singleton. There is only one instance of this class for your entire program, and it holds one user name, and one password, which is accessable from any other classes in your program. You can call it from anywhere by using the getInstance() call:

IDHolder.getInstance().setUserName("Foo");
IDHolder.getInstance().setPassword("Bar");

then retrieve it later..

String myUserName = IDHolder.getInstance().getUserName():
String myPassword = IDHolder.getInstance().getPassword();

Hope that helps!
Cheers,
Kylar
0
 
LVL 1

Expert Comment

by:klf
ID: 7178885
TLTEO

Kylar is correct.  If you have a multi-thread program you should make the getInstance method synchronized

 public synchronized static IDHolder getInstance(){
     if(null == m_instance)
         m_instance = new IDHolder();

      return m_instance;
   }
0
 
LVL 3

Expert Comment

by:randyd
ID: 7180931
the singleton is a good choice.

you could also make a id/password class instantiate one and place it as a System.setParameter() object.

this is then visible to any other class in the JVM.  

randy
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