HashSet set1 = new HashSet();
set1.add( "red" );
set1.add( "blue" );
set1.add( "green" );
HashSet set2 = new HashSet();
set2.add( "yellow" );
set2.add( "blue" );
HashSet set3 = set1.union( set2 );
HashSet set4 = set1.intersection( set2 );
System.out.println( "set1 = " + set1 );
System.out.println( "set2 = " + set2 );
System.out.println( "union of set1 and set2 = " + set3 );
System.out.println( "intersection of set1 and set2 = " + set4 );
