Serialization and deserialization of Hashtable.

• By Huw Evans
• September 12, 2000

import java.io.*;
    import java.util.Hashtable;
   
    public class Test
    {
      public static Object deserialize()
      {
        ObjectInputStream in = null;
        FileInputStream in_file = null;

        Object o = null;

        try {
          in_file = new FileInputStream("store");
          in = new ObjectInputStream(in_file);

          o = in.readObject();
          in.close();
        } catch(java.io.IOException ioe) {
          ioe.printStackTrace();
          System.exit(3);
        }

        return o;
      }

      public static void serialize(Object root)
      {
         ObjectOutputStream out = null;
         FileOutputStream out_file = null;
     
         try {
           out_file = new FileOutputStream("store");
           out = new ObjectOutputStream(out_file);

           out.writeObject(root);
           out.close();
         } catch(java.io.IOException ioe) {
           ioe.printStackTrace();
           System.exit(1);
         } catch(java.lang.ClassNotFoundException cnfe) {
           cnfe.printStackTrace();
           System.exit(2);
         }
      }

      public static void main(String argv[])
      {
        Hashtable table = new Hashtable();

        Key k = new Key();
        Value v = new Value();

        table.put(k, v);

        System.out.println("Value: " + table.get(k));
        System.out.println("Writing table: " + table);

        serialize(table);

        Hashtable new_table = (Hashtable) deserialize();

        System.out.println("Reading table: " + new_table);
        System.out.println("Value: " + new_table.get(k));
      }
    }