Re: access hashtable within a hashtable

From:

"Piet" <pit.grinja@gmx.de>

Newsgroups:

comp.lang.java.help

Date:

31 Aug 2006 00:42:34 -0700

Message-ID:

<1157010154.558676.281110@h48g2000cwc.googlegroups.com>

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

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