diff --git a/core-java-collections/pom.xml b/core-java-collections/pom.xml index d3ef953e01..31f0d7419f 100644 --- a/core-java-collections/pom.xml +++ b/core-java-collections/pom.xml @@ -61,7 +61,7 @@ 1.19 1.2.0 - 3.5 + 3.8.1 4.1 4.01 1.7.0 diff --git a/core-java-collections/src/main/java/com/baeldung/array/operations/ArrayOperations.java b/core-java-collections/src/main/java/com/baeldung/array/operations/ArrayOperations.java new file mode 100644 index 0000000000..98155ed952 --- /dev/null +++ b/core-java-collections/src/main/java/com/baeldung/array/operations/ArrayOperations.java @@ -0,0 +1,197 @@ +package com.baeldung.array.operations; + +import java.lang.reflect.Array; +import java.util.Arrays; +import java.util.HashSet; +import java.util.LinkedHashSet; +import java.util.Random; +import java.util.Set; +import java.util.function.Function; +import java.util.function.IntPredicate; +import java.util.function.Predicate; + +import org.apache.commons.lang3.ArrayUtils; + +public class ArrayOperations { + + // Get the first and last item of an array + public static T getFirstObject(T[] array) { + return array[0]; + } + + public static int getFirstInt(int[] array) { + return array[0]; + } + + public static T getLastObject(T[] array) { + return array[array.length - 1]; + } + + public static int getLastInt(int[] array) { + return array[array.length - 1]; + } + + // Append a new item to an array + public static T[] appendObject(T[] array, T newItem) { + return ArrayUtils.add(array, newItem); + } + + public static int[] appendInt(int[] array, int newItem) { + int[] newArray = Arrays.copyOf(array, array.length + 1); + newArray[newArray.length - 1] = newItem; + return newArray; + } + + public static int[] appendIntWithUtils(int[] array, int newItem) { + return ArrayUtils.add(array, newItem); + } + + // Compare two arrays to check if they have the same elements + public static boolean compareObjectArrays(T[] array1, T[] array2) { + return Arrays.equals(array1, array2); + } + + public static boolean compareIntArrays(int[] array1, int[] array2) { + return Arrays.equals(array1, array2); + } + + // Deep Compare (for nested arrays) + public static boolean deepCompareObjectArrayUsingArrays(T[][] array1, T[][] array2) { + // We can use Objects.deepEquals for a broader approach + return Arrays.deepEquals(array1, array2); + } + + public static boolean deepCompareIntArrayUsingArrays(int[][] array1, int[][] array2) { + return Arrays.deepEquals(array1, array2); + } + + // Check if array is empty + public static boolean isEmptyObjectArrayUsingUtils(T[] array1) { + return ArrayUtils.isEmpty(array1); + } + + public static boolean isEmptyIntArrayUsingUtils(int[] array1) { + return ArrayUtils.isEmpty(array1); + } + + // Remove duplicates + public static Integer[] removeDuplicateObjects(Integer[] array) { + // We can use other ways of converting the array to a set too + Set set = new HashSet<>(Arrays.asList(array)); + return set.toArray(new Integer[set.size()]); + } + + public static int[] removeDuplicateInts(int[] array) { + // Box + Integer[] list = ArrayUtils.toObject(array); + // Remove duplicates + Set set = new HashSet(Arrays.asList(list)); + // Create array and unbox + return ArrayUtils.toPrimitive(set.toArray(new Integer[set.size()])); + } + + // Remove duplicates preserving the order + public static Integer[] removeDuplicateWithOrderObjectArray(Integer[] array) { + // We can use other ways of converting the array to a set too + Set set = new LinkedHashSet<>(Arrays.asList(array)); + return set.toArray(new Integer[set.size()]); + } + + public static int[] removeDuplicateWithOrderIntArray(int[] array) { + // Box + Integer[] list = ArrayUtils.toObject(array); + // Remove duplicates + Set set = new LinkedHashSet(Arrays.asList(list)); + // Create array and unbox + return ArrayUtils.toPrimitive(set.toArray(new Integer[set.size()])); + } + + // Print an array + public static String printObjectArray(Integer[] array) { + return ArrayUtils.toString(array); + } + + public static String printObjectArray(Integer[][] array) { + return ArrayUtils.toString(array); + } + + public static String printIntArray(int[] array) { + return ArrayUtils.toString(array); + } + + public static String printIntArray(int[][] array) { + return ArrayUtils.toString(array); + } + + // Box or Unbox values + public static int[] unboxIntegerArray(Integer[] array) { + return ArrayUtils.toPrimitive(array); + } + + public static Integer[] boxIntArray(int[] array) { + return ArrayUtils.toObject(array); + } + + // Map array values + @SuppressWarnings("unchecked") + public static U[] mapObjectArray(T[] array, Function function, Class targetClazz) { + U[] newArray = (U[]) Array.newInstance(targetClazz, array.length); + for (int i = 0; i < array.length; i++) { + newArray[i] = function.apply(array[i]); + } + return newArray; + } + + public static String[] mapIntArrayToString(int[] array) { + return Arrays.stream(array) + .mapToObj(value -> String.format("Value: %s", value)) + .toArray(String[]::new); + } + + // Filter array values + public static Integer[] filterObjectArray(Integer[] array, Predicate predicate) { + return Arrays.stream(array) + .filter(predicate) + .toArray(Integer[]::new); + } + + public static int[] filterIntArray(int[] array, IntPredicate predicate) { + return Arrays.stream(array) + .filter(predicate) + .toArray(); + } + + // Insert item between others + public static int[] insertBetweenIntArray(int[] array, int... values) { + return ArrayUtils.insert(2, array, values); + } + + @SuppressWarnings("unchecked") + public static T[] insertBetweenObjectArray(T[] array, T... values) { + return ArrayUtils.insert(2, array, values); + } + + // Shuffling arrays + public static int[] shuffleIntArray(int[] array) { + // we create a different array instance for testing purposes + int[] shuffled = Arrays.copyOf(array, array.length); + ArrayUtils.shuffle(shuffled); + return shuffled; + } + + public static T[] shuffleObjectArray(T[] array) { + // we create a different array instance for testing purposes + T[] shuffled = Arrays.copyOf(array, array.length); + ArrayUtils.shuffle(shuffled); + return shuffled; + } + + // Get random number + public static int getRandomFromIntArray(int[] array) { + return array[new Random().nextInt(array.length)]; + } + + public static T getRandomFromObjectArray(T[] array) { + return array[new Random().nextInt(array.length)]; + } +} diff --git a/core-java-collections/src/test/java/com/baeldung/array/operations/ArrayOperationsUnitTest.java b/core-java-collections/src/test/java/com/baeldung/array/operations/ArrayOperationsUnitTest.java new file mode 100644 index 0000000000..a9c6d97d9f --- /dev/null +++ b/core-java-collections/src/test/java/com/baeldung/array/operations/ArrayOperationsUnitTest.java @@ -0,0 +1,365 @@ +package com.baeldung.array.operations; + +import static org.assertj.core.api.Assertions.assertThat; + +import java.util.Arrays; + +import org.assertj.core.api.Condition; +import org.junit.jupiter.api.BeforeEach; +import org.junit.jupiter.api.Test; + +public class ArrayOperationsUnitTest { + + private Integer[] defaultObjectArray; + private int[] defaultIntArray; + private Integer[][] defaultJaggedObjectArray; + private int[][] defaultJaggedIntArray; + + @BeforeEach + public void setupDefaults() { + defaultObjectArray = new Integer[] { 3, 5, 2, 5, 14, 4 }; + defaultIntArray = new int[] { 3, 5, 2, 5, 14, 4 }; + defaultJaggedObjectArray = new Integer[][] { { 1, 3 }, { 5 }, {} }; + defaultJaggedIntArray = new int[][] { { 1, 3 }, { 5 }, {} }; + } + + // Get the first and last item of an array + @Test + public void whenGetFirstObjectCalled_thenReturnFirstItemOfArray() { + Integer output = ArrayOperations.getFirstObject(defaultObjectArray); + + assertThat(output).isEqualTo(3); + } + + @Test + public void whenGetFirstIntCalled_thenReturnFirstItemOfArray() { + int output = ArrayOperations.getFirstInt(defaultIntArray); + + assertThat(output).isEqualTo(3); + } + + @Test + public void whenGetLastObjectCalled_thenReturnLastItemOfArray() { + Integer output = ArrayOperations.getLastObject(defaultObjectArray); + + assertThat(output).isEqualTo(4); + } + + @Test + public void whenGetLastIntCalled_thenReturnLastItemOfArray() { + int output = ArrayOperations.getLastInt(defaultIntArray); + + assertThat(output).isEqualTo(4); + } + + // Append a new item to an array + @Test + public void whenAppendObject_thenReturnArrayWithExtraItem() { + Integer[] output = ArrayOperations.appendObject(defaultObjectArray, 7); + + assertThat(output).endsWith(4, 7) + .hasSize(7); + } + + @Test + public void whenAppendInt_thenReturnArrayWithExtraItem() { + int[] output = ArrayOperations.appendInt(defaultIntArray, 7); + int[] outputUsingUtils = ArrayOperations.appendIntWithUtils(defaultIntArray, 7); + + assertThat(output).endsWith(4, 7) + .hasSize(7); + assertThat(outputUsingUtils).endsWith(4, 7) + .hasSize(7); + } + + // Compare two arrays to check if they have the same elements + @Test + public void whenCompareObjectArrays_thenReturnBoolean() { + Integer[] array2 = { 8, 7, 6 }; + Integer[] sameArray = { 3, 5, 2, 5, 14, 4 }; + boolean output = ArrayOperations.compareObjectArrays(defaultObjectArray, array2); + boolean output2 = ArrayOperations.compareObjectArrays(defaultObjectArray, sameArray); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + } + + @Test + public void whenCompareIntArrays_thenReturnBoolean() { + int[] array2 = { 8, 7, 6 }; + int[] sameArray = { 3, 5, 2, 5, 14, 4 }; + boolean output = ArrayOperations.compareIntArrays(defaultIntArray, array2); + boolean output2 = ArrayOperations.compareIntArrays(defaultIntArray, sameArray); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + } + + // Deep compare + @Test + public void whenDeepCompareObjectArrays_thenReturnBoolean() { + Integer[][] sameArray = { { 1, 3 }, { 5 }, {} }; + Integer[][] array2 = { { 1, 3 }, { 5 }, { 3 } }; + boolean output = ArrayOperations.deepCompareObjectArrayUsingArrays(defaultJaggedObjectArray, array2); + boolean output2 = ArrayOperations.deepCompareObjectArrayUsingArrays(defaultJaggedObjectArray, sameArray); + // Because arrays are Objects, we could wrongly use the non-deep approach + boolean outputUsingNonDeep = ArrayOperations.compareObjectArrays(defaultJaggedObjectArray, sameArray); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + // This is not what we would expect! + assertThat(outputUsingNonDeep).isFalse(); + } + + @Test + public void whenDeepCompareIntArrays_thenReturnBoolean() { + int[][] sameArray = { { 1, 3 }, { 5 }, {} }; + int[][] array2 = { { 1, 3 }, { 5 }, { 3 } }; + boolean output = ArrayOperations.deepCompareIntArrayUsingArrays(defaultJaggedIntArray, array2); + boolean output2 = ArrayOperations.deepCompareIntArrayUsingArrays(defaultJaggedIntArray, sameArray); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + } + + // Empty Check + @Test + public void whenIsEmptyObjectArray_thenReturnBoolean() { + Integer[] array2 = {}; + Integer[] array3 = null; + Integer[] array4 = { null, null, null }; + Integer[] array5 = { null }; + Integer[][] array6 = { {}, {}, {} }; + boolean output = ArrayOperations.isEmptyObjectArrayUsingUtils(defaultObjectArray); + boolean output2 = ArrayOperations.isEmptyObjectArrayUsingUtils(array2); + boolean output3 = ArrayOperations.isEmptyObjectArrayUsingUtils(array3); + boolean output4 = ArrayOperations.isEmptyObjectArrayUsingUtils(array4); + boolean output5 = ArrayOperations.isEmptyObjectArrayUsingUtils(array5); + boolean output6 = ArrayOperations.isEmptyObjectArrayUsingUtils(array6); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + assertThat(output3).isTrue(); + // Mind these edge cases! + assertThat(output4).isFalse(); + assertThat(output5).isFalse(); + assertThat(output6).isFalse(); + } + + @Test + public void whenIsEmptyIntArray_thenReturnBoolean() { + int[] array2 = {}; + boolean output = ArrayOperations.isEmptyIntArrayUsingUtils(defaultIntArray); + boolean output2 = ArrayOperations.isEmptyIntArrayUsingUtils(array2); + + assertThat(output).isFalse(); + assertThat(output2).isTrue(); + } + + // Remove Duplicates + @Test + public void whenRemoveDuplicateObjectArray_thenReturnArrayWithNoDuplicates() { + Integer[] output = ArrayOperations.removeDuplicateObjects(defaultObjectArray); + + assertThat(output).containsOnlyOnce(5) + .hasSize(5) + .doesNotHaveDuplicates(); + } + + @Test + public void whenRemoveDuplicateIntArray_thenReturnArrayWithNoDuplicates() { + int[] output = ArrayOperations.removeDuplicateInts(defaultIntArray); + + assertThat(output).containsOnlyOnce(5) + .hasSize(5) + .doesNotHaveDuplicates(); + } + + // Remove Duplicates Preserving order + @Test + public void whenRemoveDuplicatePreservingOrderObjectArray_thenReturnArrayWithNoDuplicates() { + Integer[] array2 = { 3, 5, 2, 14, 4 }; + Integer[] output = ArrayOperations.removeDuplicateWithOrderObjectArray(defaultObjectArray); + + assertThat(output).containsOnlyOnce(5) + .hasSize(5) + .containsExactly(array2); + } + + @Test + public void whenRemoveDuplicatePreservingOrderIntArray_thenReturnArrayWithNoDuplicates() { + int[] array2 = { 3, 5, 2, 14, 4 }; + int[] output = ArrayOperations.removeDuplicateWithOrderIntArray(defaultIntArray); + + assertThat(output).containsOnlyOnce(5) + .hasSize(5) + .containsExactly(array2); + } + + // Print + @Test + public void whenPrintObjectArray_thenReturnString() { + String output = ArrayOperations.printObjectArray(defaultObjectArray); + String jaggedOutput = ArrayOperations.printObjectArray(defaultJaggedObjectArray); + // Comparing to Arrays output: + String wrongArraysOutput = Arrays.toString(defaultJaggedObjectArray); + String differentFormatArraysOutput = Arrays.toString(defaultObjectArray); + // We should use Arrays.deepToString for jagged arrays + String differentFormatJaggedArraysOutput = Arrays.deepToString(defaultJaggedObjectArray); + + assertThat(output).isEqualTo("{3,5,2,5,14,4}"); + assertThat(jaggedOutput).isEqualTo("{{1,3},{5},{}}"); + assertThat(differentFormatArraysOutput).isEqualTo("[3, 5, 2, 5, 14, 4]"); + assertThat(wrongArraysOutput).contains("[[Ljava.lang.Integer;@"); + assertThat(differentFormatJaggedArraysOutput).contains("[[1, 3], [5], []]"); + } + + @Test + public void whenPrintIntArray_thenReturnString() { + String output = ArrayOperations.printIntArray(defaultIntArray); + String jaggedOutput = ArrayOperations.printIntArray(defaultJaggedIntArray); + // Comparing to Arrays output: + String wrongArraysOutput = Arrays.toString(defaultJaggedObjectArray); + String differentFormatArraysOutput = Arrays.toString(defaultObjectArray); + + assertThat(output).isEqualTo("{3,5,2,5,14,4}"); + assertThat(jaggedOutput).isEqualTo("{{1,3},{5},{}}"); + assertThat(differentFormatArraysOutput).isEqualTo("[3, 5, 2, 5, 14, 4]"); + assertThat(wrongArraysOutput).contains("[[Ljava.lang.Integer;@"); + } + + // Box and unbox + @Test + public void whenUnboxObjectArray_thenReturnPrimitiveArray() { + int[] output = ArrayOperations.unboxIntegerArray(defaultObjectArray); + + assertThat(output).containsExactly(defaultIntArray); + } + + @Test + public void henBoxPrimitiveArray_thenReturnObjectArray() { + Integer[] output = ArrayOperations.boxIntArray(defaultIntArray); + + assertThat(output).containsExactly(defaultObjectArray); + } + + // Map values + @Test + public void whenMapMultiplyingObjectArray_thenReturnMultipliedArray() { + Integer[] multipliedExpectedArray = new Integer[] { 6, 10, 4, 10, 28, 8 }; + Integer[] output = ArrayOperations.mapObjectArray(defaultObjectArray, value -> value * 2, Integer.class); + + assertThat(output).containsExactly(multipliedExpectedArray); + } + + @Test + public void whenMapDividingObjectArray_thenReturnDividedArray() { + Double[] multipliedExpectedArray = new Double[] { 1.5, 2.5, 1.0, 2.5, 7.0, 2.0 }; + Double[] output = ArrayOperations.mapObjectArray(defaultObjectArray, value -> value / 2.0, Double.class); + + assertThat(output).containsExactly(multipliedExpectedArray); + } + + @Test + public void whenMapIntArrayToString_thenReturnArray() { + String[] expectedArray = new String[] { "Value: 3", "Value: 5", "Value: 2", "Value: 5", "Value: 14", + "Value: 4" }; + String[] output = ArrayOperations.mapIntArrayToString(defaultIntArray); + + assertThat(output).containsExactly(expectedArray); + } + + // Filter values + @Test + public void whenFilterObjectArray_thenReturnFilteredArray() { + Integer[] multipliedExpectedArray = new Integer[] { 2, 14, 4 }; + Integer[] output = ArrayOperations.filterObjectArray(defaultObjectArray, value -> value % 2 == 0); + + assertThat(output).containsExactly(multipliedExpectedArray); + } + + @Test + public void whenFilterIntArray_thenReturnFilteredArray() { + int[] expectedArray = new int[] { 2, 14, 4 }; + int[] output = ArrayOperations.filterIntArray(defaultIntArray, value -> (int) value % 2 == 0); + + assertThat(output).containsExactly(expectedArray); + } + + // Insert between + @Test + public void whenInsertBetweenIntArrayToString_thenReturnNewArray() { + int[] expectedArray = { 3, 5, 77, 88, 2, 5, 14, 4 }; + int[] output = ArrayOperations.insertBetweenIntArray(defaultIntArray, 77, 88); + + assertThat(output).containsExactly(expectedArray); + } + + @Test + public void whenInsertBetweenObjectArrayToString_thenReturnNewArray() { + Integer[] expectedArray = { 3, 5, 77, 99, 2, 5, 14, 4 }; + Integer[] output = ArrayOperations.insertBetweenObjectArray(defaultObjectArray, 77, 99); + + assertThat(output).containsExactly(expectedArray); + } + + // Shuffle between + @Test + public void whenShufflingIntArraySeveralTimes_thenAtLeastOneWithDifferentOrder() { + int[] output = ArrayOperations.shuffleIntArray(defaultIntArray); + int[] output2 = ArrayOperations.shuffleIntArray(defaultIntArray); + int[] output3 = ArrayOperations.shuffleIntArray(defaultIntArray); + int[] output4 = ArrayOperations.shuffleIntArray(defaultIntArray); + int[] output5 = ArrayOperations.shuffleIntArray(defaultIntArray); + int[] output6 = ArrayOperations.shuffleIntArray(defaultIntArray); + + Condition atLeastOneArraysIsNotEqual = new Condition( + "at least one output should be different (order-wise)") { + @Override + public boolean matches(int[] value) { + return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3) + || !Arrays.equals(value, output4) || !Arrays.equals(value, output5) + || !Arrays.equals(value, output6); + } + }; + + assertThat(defaultIntArray).has(atLeastOneArraysIsNotEqual); + } + + @Test + public void whenShufflingObjectArraySeveralTimes_thenAtLeastOneWithDifferentOrder() { + Integer[] output = ArrayOperations.shuffleObjectArray(defaultObjectArray); + Integer[] output2 = ArrayOperations.shuffleObjectArray(defaultObjectArray); + Integer[] output3 = ArrayOperations.shuffleObjectArray(defaultObjectArray); + Integer[] output4 = ArrayOperations.shuffleObjectArray(defaultObjectArray); + Integer[] output5 = ArrayOperations.shuffleObjectArray(defaultObjectArray); + Integer[] output6 = ArrayOperations.shuffleObjectArray(defaultObjectArray); + + Condition atLeastOneArraysIsNotEqual = new Condition( + "at least one output should be different (order-wise)") { + @Override + public boolean matches(Integer[] value) { + return !Arrays.equals(value, output) || !Arrays.equals(value, output2) || !Arrays.equals(value, output3) + || !Arrays.equals(value, output4) || !Arrays.equals(value, output5) + || !Arrays.equals(value, output6); + } + }; + + assertThat(defaultObjectArray).has(atLeastOneArraysIsNotEqual); + } + + // Get random item + @Test + public void whenGetRandomFromIntArrayToString_thenReturnItemContainedInArray() { + int output = ArrayOperations.getRandomFromIntArray(defaultIntArray); + + assertThat(defaultIntArray).contains(output); + } + + @Test + public void whenGetRandomFromObjectArrayToString_thenReturnItemContainedInArray() { + Integer output = ArrayOperations.getRandomFromObjectArray(defaultObjectArray); + + assertThat(defaultObjectArray).contains(output); + } +}