How would I search the hastable for homer?

Question

This is an example that I did awhile back. I currently messing around with it just as a review. I got stuck on how I can implement a search for my hashtable. Here is what I have so far
import java.util.*;
public class SimpsonsClient {
    public static void main(String args[]) {
      Hashtable hash = new Hashtable();
      Student st1 = new Student("Homer", "Simpson", "0");
      Student st2 = new Student("Marge", "Simpson", "0");
      Student st3 = new Student("Bart", "Simpson", "0");
      Student st4 = new Student("Lisa", "Simpson", "0");
      Student st5 = new Student("Maggie", "Simpson", "0");
      System.out.println("Adding values to hash");
      hash.put(st1.getAge(), st1);
      hash.put(st2.getAge(), st2);
      hash.put(st3.getAge(), st3);
      hash.put(st4.getAge(), st4);
      hash.put(st4.getAge(), st5);
      System.out.println("Does the hash have st1?:" + hash.contains(st1));
      System.out.println("Is the hash code empty?" + hash.isEmpty());
      //Search for homer?
      System.out.println("Hash contain Homer?" + hash.get("Homer"));
    }Output Looks like this:
Adding values to hash
Does the hash have st1?:true
Is the hash code empty?false
Hash contain Homer?null
I just would like to know how I can do a search for homer and pull his records off like the name, age, and the field of 1.
Thanks

Answer 1

import java.util.*;
public class SimpsonsClient {
    public static void main(String args[]) {
      Hashtable hash = new Hashtable();
      Student st1 = new Student("Homer", "Simpson", "0");
      Student st2 = new Student("Marge", "Simpson", "0");
      Student st3 = new Student("Bart", "Simpson", "0");
      Student st4 = new Student("Lisa", "Simpson", "0");
      Student st5 = new Student("Maggie", "Simpson", "0");
      hash.put(st1.getAge(), st1);
      hash.put(st2.getAge(), st2);
      hash.put(st3.getAge(), st3);
      hash.put(st4.getAge(), st4);
      hash.put(st4.getAge(), st5);
    }I can't really tell actually. You haven't included a definition for the Student class. If it's something like this:
public class Student
  public String getName();
  public String getSurname();
  public String getValue(); // the third field
}In the old jdk 1.1 API
public static boolean tableContainsStudent(Hashtable table, String name)
  for(Enumeration students = table.elements(); students.hasMoreElements(); )
    if (((Student)students.nextElement()).getName().equals(name)) return true;
  return false;
}It's quite similar with Collections API
for (Iterator students=table.values().iterator();students.hasNext(); )
  if (((Student)students.nextElement()).getName().equals(name)) return true;
return false;
...I don't think the Hashtable is optimal at all for searching this way. It would be much nicer if you can do a binary search, but that requires more thinking when designing the storage class.
greets.