added more methods

Author: Pratik Das

core-java/collectionops/src/main/java/io/pratik/CollectionHelper.java

@@ -4,14 +4,19 @@
 package io.pratik;
 
 import java.util.ArrayList;
+import java.util.Collection;
 import java.util.Collections;
 import java.util.HashSet;
+import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
 import java.util.stream.Stream;
 
+import com.google.common.collect.Lists;
+
 /**
  * @author pratikdas
  *
@@ -22,6 +27,7 @@ public <T> List<T>[] split(List<T> listToSplit){
 	    // determine the endpoints to use in `list.subList()` method
 	    int[] endpoints = {0, (listToSplit.size() + 1)/2, listToSplit.size()};
 
+	    
 	    List<List<T>> sublists =
 	            IntStream.rangeClosed(0, 1)
 	                    .mapToObj(i -> listToSplit.subList(endpoints[i], endpoints[i + 1]))
@@ -49,7 +55,7 @@ public List<Integer> addWithFilter(final List<Integer> collA, final List<Integer
 	}	
 
 	public List<Integer> union(final List<Integer> collA, final List<Integer> collB){
-		Set<Integer> set = new HashSet<>();
+		Set<Integer> set = new LinkedHashSet<>();
 		set.addAll(collA);
 		set.addAll(collB);
 
@@ -70,6 +76,49 @@ public List<Integer> intersection(final List<Integer> collA, final List<Integer>
 
 	}
 
+	public Collection<List<Integer>> partition(final List<Integer> collA, final int chunkSize){
+		final AtomicInteger counter = new AtomicInteger();
+
+		final Collection<List<Integer>> result = collA.stream()
+		    .collect(Collectors.groupingBy(it -> counter.getAndIncrement() / chunkSize))
+		    .values();
+
+		return result;
+		
+	}
+	
+
+	public List<Integer> removeDuplicates(final List<Integer> collA){
+      List<Integer> listWithoutDuplicates = new ArrayList<>(
+         new LinkedHashSet<>(collA));
+      
+      return listWithoutDuplicates;
+	}
+	
+	public List<Integer> xor(final List<Integer> collA, final List<Integer> collB){
+	      
+	      List<Integer> listOfAnotInB = collA.stream().filter(element->{
+	    	  return !collB.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      List<Integer> listOfBnotInA = collB.stream().filter(element->{
+	    	  return !collA.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      return Stream.concat(listOfAnotInB.stream(), 
+	    		  listOfBnotInA.stream())
+	    			.collect(Collectors.toList());
+	}
+	
+	public List<Integer> not(final List<Integer> collA, final List<Integer> collB){
+		  
+		  List<Integer> notList = collA.stream().filter(element->{
+	    	  return !collB.contains(element);
+	      }).collect(Collectors.toList());
+	      
+	      return notList;
+	}
+	
 	public List<Integer> subtract(final List<Integer> collA, final List<Integer> collB){
 		List<Integer> intersectElements = intersection(collA,collB);
 

core-java/collectionops/src/test/java/io/pratik/tests/CollectionHelperTest.java

@@ -3,6 +3,10 @@
  */
 package io.pratik.tests;
 
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+
+import java.util.Collection;
+import java.util.Iterator;
 import java.util.List;
 
 import org.junit.jupiter.api.AfterEach;
@@ -38,12 +42,12 @@ void tearDown() throws Exception {
 	@Test
 	void testUnion() {
 		List<Integer> union = collectionHelper.union(
-				List.of(9,8,5,4,7), 
-				List.of(1,3,99,4,7));
+				List.of(9, 8, 5, 4, 7), 
+				List.of(1, 3, 99, 4, 7));
 
 
 		Assertions.assertArrayEquals(
-				List.of(1, 3, 99, 4, 5, 7, 8, 9).toArray(), 
+				List.of(9, 8, 5, 4, 7, 1, 3, 99).toArray(), 
 				union.toArray());
 
 	}
@@ -59,6 +63,28 @@ void testIntersection() {
 				intersection.toArray());
 	}
 
+	@Test
+	void testXOR() {
+		List<Integer> xorList = collectionHelper.xor(
+				List.of(9, 8,  5, 4, 7), 
+				List.of(1, 99, 4, 7));
+		
+		Assertions.assertArrayEquals(
+				List.of(9, 8, 5, 1, 99).toArray(), 
+				xorList.toArray());
+	}
+	
+	@Test
+	void testNOT() {
+		List<Integer> xorList = collectionHelper.not(
+				List.of(9,8,5,4,7), 
+				List.of(1,99,4,7));
+		
+		Assertions.assertArrayEquals(
+				List.of(9,8,5).toArray(), 
+				xorList.toArray());
+	}
+	
 	@Test
 	void testAddition() {
 		List<Integer> sub = collectionHelper.add(
@@ -96,10 +122,48 @@ void testSubtraction() {
 				sub.toArray());
 	}
 
+	@Test
+	void testPartition() {
+		Collection<List<Integer>> partitions = collectionHelper.partition(
+				List.of(9, 8, 5, 4, 7, 15, 15), 2);
+		
+		Iterator<List<Integer>> iter = partitions.iterator();
+		
+		int loop = 0;
+		while(iter.hasNext()) {
+			List<Integer> element = iter.next();
+			System.out.println(element);
+			if(loop == 0)
+			   assertArrayEquals(List.of(9, 8).toArray(),element.toArray());
+			else if(loop == 1)
+				   assertArrayEquals(List.of(5, 4).toArray(),element.toArray());
+			else if(loop == 2)
+				   assertArrayEquals(List.of(7, 15).toArray(),element.toArray());
+			else if(loop == 3)
+				   assertArrayEquals(List.of(15).toArray(),element.toArray());
+		
+			++loop;
+		}
+		
+	
+	}
+	
+	@Test
+	void testRemoveDuplicates() {
+		List<Integer> uniqueElements = collectionHelper.removeDuplicates(
+				List.of(9, 8, 5, 4, 4, 7, 15, 15));
+		
+		
+		
+		Assertions.assertArrayEquals(
+				List.of(9, 8, 5, 4, 7, 15).toArray(), 
+				uniqueElements.toArray());
+	}
+	
 	@Test
 	void testSplit() {
 		List<Integer>[] subLists = collectionHelper.split(
-				List.of(9,8,5,4,7, 15, 15));
+				List.of(9, 8, 5, 4, 7, 15, 15));
 
 
 		Assertions.assertArrayEquals(