ArrayLists and Iterators

15. isEmpty()

Answer:
0: Amy
1: Bob
2: Deb

`isEmpty()`

To check if an ArrayList has elements use

boolean isEmpty()

which returns true if the cells of the ArrayList are all empty.

Warning:The value null in a cell counts as data. An empty cell is not the same as a cell that contains null.

To remove all elements from a list, use

void clear()

Question 15:
(Puzzle: ) What will the following program print?

    
        
        
        
                           import java.util.* ;
public class NullPuzzle
{
  public static void main ( String[] args)
  {
    ArrayList<String> nobby = new ArrayList<String>();

    System.out.println( "Case A:" + nobby.isEmpty() );
    
    nobby.add( null );    
    System.out.println( "Case B:" + nobby.isEmpty() );
    
    nobby.remove( 0 );  
    System.out.println( "Case C:" + nobby.isEmpty() );
    
    nobby.add( "" );    
    System.out.println( "Case D:" + nobby.isEmpty() );
    
    nobby.clear( );    
    System.out.println( "Case E:" + nobby.isEmpty() );

  }
}