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Java Forum / First Aid / August 2006

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access hashtable within a hashtable

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ssavasta@us.ibm.com - 31 Aug 2006 03:44 GMT
HI:

can someone show me how to access and print a hashtable that's part of
the data of another hashtable?
the way i do it now the output is so long that it make the generated
log file unopenable in
in an editor (unix VI)

here is an example that illustrates my problem

cat PrintHashtable.java
import java.util.*;

public class PrintHashtable {

 public static void main(String[] args) {
   // Create and populate hashtable
   Hashtable ht = new Hashtable();
   ht.put("ABC", "abc");
   ht.put("XYZ", "xyz");
   ht.put("MNO", "mno");
       Hashtable htData1 = new Hashtable();
       htData1.put("CBA1", "abc1");
       htData1.put("CBA2", "abc2");
       htData1.put("CBA3", "abc3");
       htData1.put("CBA3", "abc33");
       ht.put("ABCD", htData1);

   // Display hashtable.
       Enumeration e = ht.keys();
       String key = null;
       while(e.hasMoreElements()){
     key = (String)e.nextElement();
     System.out.println("Key: " + key + "     Val: " +  ht.get(key));
   }

 }
}

Compile:
javac PrintHashtable.java

Execute:
java PrintHashtable
Key: ABCD     Val: {CBA1=abc1, CBA3=abc33, CBA2=abc2}
Key: ABC     Val: abc
Key: MNO     Val: mno
Key: XYZ     Val: xyz

the problem with the output is with first line:
Key: ABCD     Val: {CBA1=abc1, CBA3=abc33, CBA2=abc2}

in the real application it can be thousands of characters long.
so i would like the output to be more like (for example):
Key: ABCD     Val: {CBA1=abc1,
CBA3=abc33,
CBA2=abc2}
Key: ABC     Val: abc
Key: MNO     Val: mno
Key: XYZ     Val: xyz

that is break it up into multiple lines.

any help is appreciated.

thanks
Piet - 31 Aug 2006 08:42 GMT
> can someone show me how to access and print a hashtable that's part of
> the data of another hashtable?
> the way i do it now the output is so long that it make the generated
> log file unopenable in
> in an editor (unix VI)

> here is an example that illustrates my problem
>
[quoted text clipped - 48 lines]
> Key: MNO     Val: mno
> Key: XYZ     Val: xyz

you need to distinguish between two types of values in ht: values that
are simple strings and values that represent "inner hashtables". In the
former case, the value can simply be printed, in the latter case,
iterate over the inner hashtable and print the individual elements
using a appropriate formatting, something like (untested pseudocode):

>     // Display hashtable.
>         Enumeration e = ht.keys();
>         String key = null;
>         while(e.hasMoreElements()){
>       key = (String)e.nextElement();
>       if ht.getKey() instanceOf HashTable(){
           System.out.prinln("Key: "+key+"   Val: inner hashtable");
           HashTable inner = ht.get(key);
           Enumeration ie = inner.keys();
           while ie.hasMoreElements(){
               System.out.println("\tKey: " + key + "     Val: " +
ht.get(key)+"\n")
           }
        }
        else{
        System.out.println("Key: " + key + "     Val: " +
ht.get(key));
>     }
HTH
Piet
Oliver Wong - 31 Aug 2006 14:33 GMT
> HI:
>
[quoted text clipped - 60 lines]
>
> any help is appreciated.

   I'd create my own subclass of HashTable to replace your inner hashtable
and override the toString() method.

   - Oliver


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