Binary search trees - Data Structures and Problem Solving Using Java - page 748

1 public void remove( )
2 {
3 if( expectedModCount != modCount )
4 throw new ConcurrentModificationException( );
5
6 if( lastVisited == null )
7 throw new IllegalStateException( );
8
9 AnyType valueToRemove = lastVisited.element;
10
11 TreeSet.this.remove( valueToRemove );
12
13 expectedModCount++;
14 visited--;
15 lastVisited = null;
16
17 if( !hasNext( ) )
18 return;
19
20 // Remaining code reinstates the stack, in case of rotations
21 AnyType nextValue = current.element;
22 path.clear( );
23 AANode<AnyType> p = root;
24 for( ; ; )
25 {
26 path.push( p );
27 int result = compare( nextValue, p.element );
28 if( result < 0 )
29 p = p.left;
30 else if( result > 0 )
31 p = p.right;
32 else
33 break;
34 }
35 path.pop( );
36 current = p;
37 }
figure 19.76
remove method for TreeSetIterator
by providing compareTo , while in HashMap it is extended by providing equals
and hashCode .
Lines 17-21 declare the three abstract methods. These are factories that
create the appropriate concrete object and return it through the interface type.
For instance, in TreeMap , makeEmptyKeySet returns a newly constructed TreeSet ,
whereas in HashMap , makeEmptyKeySet returns a newly constructed HashSet .
Most important, makePair creates an object of type Map.Entry that represents