java union and intersection

String[] arrayA = new String[] { "1", "2", "3", "3", "4", "5" };  
String[] arrayB = new String[] { "3", "4", "4", "5", "6", "7" };  
 
List a = Arrays.asList( arrayA );  
List b = Arrays.asList( arrayB );  
 
Collection union = CollectionUtils.union( a, b );  
Collection intersection = CollectionUtils.intersection( a, b );  
Collection disjunction = CollectionUtils.disjunction( a, b );  
Collection subtract = CollectionUtils.subtract( a, b );  
 
Collections.sort( union );  
Collections.sort( intersection );  
Collections.sort( disjunction );  
Collections.sort( subtract );  
 
 
System.out.println( "A: " + ArrayUtils.toString( a.toArray( ) ) );  
System.out.println( "B: " + ArrayUtils.toString( b.toArray( ) ) );  
System.out.println( "Union: " + ArrayUtils.toString( union.toArray( ) ) );  
System.out.println( "Intersection: " +   
                    ArrayUtils.toString( intersection.toArray( ) ) );  
System.out.println( "Disjunction: " +   
                    ArrayUtils.toString( disjunction.toArray( ) ) );  
System.out.println( "Subtract: " + ArrayUtils.toString( subtract.toArray( ) ) ); 

String[] arrayA = new String[] { "1", "2", "3", "3", "4", "5" };
String[] arrayB = new String[] { "3", "4", "4", "5", "6", "7" };

List a = Arrays.asList( arrayA );
List b = Arrays.asList( arrayB );

Collection union = CollectionUtils.union( a, b );
Collection intersection = CollectionUtils.intersection( a, b );
Collection disjunction = CollectionUtils.disjunction( a, b );
Collection subtract = CollectionUtils.subtract( a, b );

Collections.sort( union );
Collections.sort( intersection );
Collections.sort( disjunction );
Collections.sort( subtract );


System.out.println( "A: " + ArrayUtils.toString( a.toArray( ) ) );
System.out.println( "B: " + ArrayUtils.toString( b.toArray( ) ) );
System.out.println( "Union: " + ArrayUtils.toString( union.toArray( ) ) );
System.out.println( "Intersection: " +
                    ArrayUtils.toString( intersection.toArray( ) ) );
System.out.println( "Disjunction: " +
                    ArrayUtils.toString( disjunction.toArray( ) ) );
System.out.println( "Subtract: " + ArrayUtils.toString( subtract.toArray( ) ) );

The previous example performs these four operations on two List objects, a and b, printing the results with ArrayUtils.toString( ):

Java代码
A: {1,2,2,2,3,3,4,5}  
B: {3,4,4,5,6,7}  
Union: {1,2,2,2,3,3,4,4,5,6,7}  
Intersection: {3,4,5}  
Disjunction: {1,2,2,2,3,4,6,7}  
Subtract: {1,2,2,2,3}