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public class ShowHeapError {

  Vector<String> names = new Vector<String>();
  String newName=null;
  InputStreamReader input = new InputStreamReader(System.in);
  BufferedReader reader = new BufferedReader(input);

  public void addNames(){
    do {
      // Adding unknown number of records to a list
      // the user can enter as much data as he wants and exhaust the heap
      System.out.print(" To quit, enter \"quit\"\nEnter record: ");
      try {
        newName = reader.readLine();
        if(!newName.equalsIgnoreCase("quit")){
          // names are continued to be added without 
          // bothering about the size on the heap
          names.addElement(newName);
        }
      } catch (IOException e) {
        // forward to handler 
      }
    
      System.out.println(newName);
    }while (!newName.equalsIgnoreCase("quit"));
  }

  public static void main(String[] args) {
    ShowHeapError demo = new ShowHeapError();
    demo.addNames();
  }
}

public class ShowHeapError {

  /* Assuming the heap size as 512 MB (calculated as 1/4th of 2 GB RAM = 512 MB)
   * Considering long values being entered (64 bits each, the max number of elements
   * would be 512 MB/64bits = 67108864)
   */
   Vector<Long> names = new Vector<Long>(67108865);
   long newID=0L;
   int count = 67108865;
   int i = 0;
   InputStreamReader input = new InputStreamReader(System.in);
   Scanner reader = new Scanner(input);

   public void addNames(){
     do{
       /* Adding unknown number of records to a list
        * the user can enter more number of IDs than what the heap can support and 
        * exhaust the heap. Assume that the record ID is a 64 bit long value
       */
       System.out.print(" To quit, enter -1\nEnter recordID: ");
       newID = reader.nextLong();
       //names are continued to be added without bothering about the size on the heap
       names.addElement(newID);
       System.out.println(newID);
       i++;

     }while (i<count || newID!=-1);
   }

   public static void main(String[] args) {
     ShowHeapError demo = new ShowHeapError();
     demo.addNames();
   }
}

FileOutputStream fos = new FileOutputStream("data.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(new Date());
// ... 

FileOutputStream fos = new FileOutputStream("data.txt");
ObjectOutputStream oos = new ObjectOutputStream(fos);
oos.writeObject(new Date());
oos.reset();  // Reset the Object-Handle table to its initial state
// ...