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hashmaps

Posted on 2004-10-14
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does anyone know the code to retrieve the data stored in a hashmap (ie String, Object) and asign it to an Object and String?
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Question by:minichicken
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29 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 12311371
Object o = map.get("x");
String s = (String)map.get("x");
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Expert Comment

by:CEHJ
ID: 12311375
(That would be dependent on what keys you have)
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Author Comment

by:minichicken
ID: 12311420
how would i get the values stored in that object? (ie make Object o = new Cleint();)
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LVL 86

Expert Comment

by:CEHJ
ID: 12311458
If Client objects are stored:

Client c = (Client)map.get("x");
String clientName = c.getName();
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Author Comment

by:minichicken
ID: 12311483
           while(true)
            {
                  soc = ss1.accept();
            
                  ObjectInputStream ois = new ObjectInputStream(soc.getInputStream());
                  
                  HashMap hm = (HashMap)ois.readObject();
                  
//                  o = hm.get("crafter");
                  
                  o = new crafter_class();
                                    
                  if(o == null)
                  {
                        System.out.println("Object does not Exist");
                  }
            
                  else
                        if(o instanceof crafter_class)
                        {
                              crafter_class cc = new crafter_class();
                              
                              String name = o.get_name();
                              String sname = o.get_sname();

                              crafter_container ccon = new crafter_container();

                              ccon.addcrafter(name,sname);                  
                        }            
            }
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Author Comment

by:minichicken
ID: 12311496
i think i need to make Object o = cc;
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Expert Comment

by:CEHJ
ID: 12311505
Why would you be *creating* objects? You should be getting them as i mentioned
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Author Comment

by:minichicken
ID: 12311553
basically i got the info stored in Object o.  but i cant get do o.get_name(); (somehow)?
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Author Comment

by:minichicken
ID: 12311559
i can give you the entire calss if you'de dig to check it?
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LVL 86

Expert Comment

by:CEHJ
ID: 12311583
if(o instanceof crafter_class)
{
    crafter_class cc = (crafter_class)o;
    String name = cc.getName();
}
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Author Comment

by:minichicken
ID: 12311624
crafter_class cc = (crafter_class)o;

i always f!@#ing forget that!!

thanks dude, it works fine now!!!! shot a kapillion!
0
 
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Author Comment

by:minichicken
ID: 12311638
but you say "String s = (String)map.get("x");" will get me the initial String decalred in the HashMap?
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Expert Comment

by:CEHJ
ID: 12311654
If there is a String in there, with "x" as a key, then yes ;-)
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LVL 12

Author Comment

by:minichicken
ID: 12311660
or how would i retrieve the String embeded in the HashMap?
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Author Comment

by:minichicken
ID: 12311669
do you have an MSN or Yahoo chat address?
0
 
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Expert Comment

by:CEHJ
ID: 12311684
I don't use IM i'm afraid
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Author Comment

by:minichicken
ID: 12311701
fine man.

so you know how to retrieve the origional String embeded in the HashMap?
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LVL 86

Expert Comment

by:CEHJ
ID: 12311712
What is its key?
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Author Comment

by:minichicken
ID: 12311742
it is the key im looking for...

ie String s = hm.get(Object o);

=> s = "crafter"
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Expert Comment

by:CEHJ
ID: 12311764
You can get all the keys thus:

Set keys = map.keySet();
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LVL 12

Author Comment

by:minichicken
ID: 12311813
then?

basically i need to get a String from the HashMap (ie "crafter") to compare with others.

it may be "product", "sales-transaction" etc.

??
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Author Comment

by:minichicken
ID: 12311832
how do i compare or view the keys?
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LVL 86

Expert Comment

by:CEHJ
ID: 12311895
Set keys = map.keySet();
Iterator iter = keys.iterator();
while (iter.hasNext()) {
      Object o = iter.next();
      if (o instanceof String) {
            System.out.println(o);
      }
}      
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LVL 8

Expert Comment

by:kiranhk
ID: 12311916
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LVL 12

Author Comment

by:minichicken
ID: 12311965
sorry dude,

it worked!  but

1. what is 'keys'?
2. what is 'Iterator' ?
3. how would i get String s = System.out.println(o); (if you know what i mean?)
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LVL 86

Expert Comment

by:CEHJ
ID: 12311998
1. 'keys' are the keys of the HashMap

2. An Iterator is to iterate the keys

3. String key = (String)o;
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LVL 8

Expert Comment

by:kiranhk
ID: 12312041
1. what is 'keys'?
keys is the variable name for your java collection Set Interface check out java.util.Set in the javadocs
2. what is 'Iterator' ?
Iterator is also the interface for moving over a collection of objects.  check out java.util.Iterator
3. how would i get String s = System.out.println(o); (if you know what i mean?)
System.out.pritnln(o) doesnt return you the string. basically what the code given above by CEHJ
means if the object O is an instance/type of java.lang.String then print the string.


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LVL 12

Author Comment

by:minichicken
ID: 12312054
crafter_class cc = (crafter_class)o;

and

String key = (String)o;

i always f!@#ing forget those!!

thanks dude, it works fine now!!!! shot a kapillion!
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Accepted Solution

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CEHJ earned 2000 total points
ID: 12312099
8-)
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