Here is an example of how to create three different empty hash tables, one that will contain objects, another for integers, and another for booleans.

public class Main {
  public static void main(String[] args){ 
    Hashtable<String, Object> objecthashtable   = new Hashtable<String, Object>();
    Hashtable<String, Integer> integerhashtable = new Hashtable<String, Integer>();
    Hashtable<String, Boolean> booleanhashtable = new Hashtable<String, Boolean>();

    System.out.println("object hash table  = " + objecthashtable);
    System.out.println("integer hash table = " + integerhashtable);
    System.out.println("boolean hash table = " + booleanhashtable);
  }
}

In this example, System.out.println will just return { }, since each hash table is empty (contains no key value pairs).

object hash table  = {}
integer hash table = {}
boolean hash table = {}

And here is how you would append key value pairs to each hash table.

public class Main {
  public static void main(String[] args){ 
    Hashtable<String, Object> objecthashtable   = new Hashtable<String, Object>();
    Hashtable<String, Integer> integerhashtable = new Hashtable<String, Integer>();
    Hashtable<String, Boolean> booleanhashtable = new Hashtable<String, Boolean>();

    objecthashtable.put("foo", "Hello");
    objecthashtable.put("bar", "World");

    integerhashtable.put("foo", 0);
    integerhashtable.put("bar", 1);

    booleanhashtable.put("foo", true);
    booleanhashtable.put("bar", false);

    System.out.println("object hash table  = " + objecthashtable);
    System.out.println("integer hash table = " + integerhashtable);
    System.out.println("boolean hash table = " + booleanhashtable);
  }
}

Now System.out.println should return key value pairs.

object hash table  = {bar=World, foo=Hello}
integer hash table = {bar=1, foo=0}
boolean hash table = {bar=false, foo=true}