diff --git a/guest/core-java/pom.xml b/guest/core-java/pom.xml index 222716386b..eda3846c1f 100644 --- a/guest/core-java/pom.xml +++ b/guest/core-java/pom.xml @@ -16,6 +16,24 @@ log4j-core ${log4j2.version} + + org.hamcrest + hamcrest-core + ${org.hamcrest.version} + test + + + org.hamcrest + hamcrest-library + ${org.hamcrest.version} + test + + + org.hamcrest + hamcrest-all + ${org.hamcrest.version} + test + @@ -32,5 +50,6 @@ 2.8.2 + 1.3 \ No newline at end of file diff --git a/guest/core-java/src/main/java/com/stackify/stream/Employee.java b/guest/core-java/src/main/java/com/stackify/stream/Employee.java new file mode 100644 index 0000000000..005990c863 --- /dev/null +++ b/guest/core-java/src/main/java/com/stackify/stream/Employee.java @@ -0,0 +1,46 @@ +package com.stackify.stream; + +public class Employee { + private Integer id; + private String name; + private Double salary; + + public Employee(Integer id, String name, Double salary) { + this.id = id; + this.name = name; + this.salary = salary; + } + + public Integer getId() { + return id; + } + + public void setId(Integer id) { + this.id = id; + } + + public String getName() { + return name; + } + + public void setName(String name) { + this.name = name; + } + + public Double getSalary() { + return salary; + } + + public void setSalary(Double salary) { + this.salary = salary; + } + + public void salaryIncrement(Double percentage) { + Double newSalary = salary + percentage * salary / 100; + setSalary(newSalary); + } + + public String toString() { + return "Id: " + id + " Name:" + name + " Price:" + salary; + } +} diff --git a/guest/core-java/src/main/java/com/stackify/stream/EmployeeRepository.java b/guest/core-java/src/main/java/com/stackify/stream/EmployeeRepository.java new file mode 100644 index 0000000000..223fee5e26 --- /dev/null +++ b/guest/core-java/src/main/java/com/stackify/stream/EmployeeRepository.java @@ -0,0 +1,21 @@ +package com.stackify.stream; + +import java.util.List; + +public class EmployeeRepository { + private List empList; + + public EmployeeRepository(List empList) { + this.empList = empList; + + } + public Employee findById(Integer id) { + for (Employee emp : empList) { + if (emp.getId() == id) { + return emp; + } + } + + return null; + } +} diff --git a/guest/core-java/src/test/java/com/stackify/stream/EmployeeTest.java b/guest/core-java/src/test/java/com/stackify/stream/EmployeeTest.java new file mode 100644 index 0000000000..cf988d035a --- /dev/null +++ b/guest/core-java/src/test/java/com/stackify/stream/EmployeeTest.java @@ -0,0 +1,455 @@ +package com.stackify.stream; + +import static org.hamcrest.CoreMatchers.equalTo; +import static org.hamcrest.MatcherAssert.assertThat; +import static org.hamcrest.Matchers.contains; +import static org.hamcrest.beans.HasPropertyWithValue.hasProperty; +import static org.junit.Assert.assertEquals; + +import java.io.IOException; +import java.io.PrintWriter; +import java.nio.file.Files; +import java.nio.file.Paths; +import java.util.Arrays; +import java.util.Collection; +import java.util.Comparator; +import java.util.DoubleSummaryStatistics; +import java.util.List; +import java.util.Map; +import java.util.NoSuchElementException; +import java.util.Optional; +import java.util.Set; +import java.util.Vector; +import java.util.function.BinaryOperator; +import java.util.stream.Collectors; +import java.util.stream.Stream; + +import org.junit.After; +import org.junit.Test; + +public class EmployeeTest { + private String fileName = "src/test/resources/test.txt"; + + private static Employee[] arrayOfEmps = { + new Employee(1, "Jeff Bezos", 100000.0), + new Employee(2, "Bill Gates", 200000.0), + new Employee(3, "Mark Zuckerberg", 300000.0) + }; + + private static List empList = Arrays.asList(arrayOfEmps); + private static EmployeeRepository employeeRepository = new EmployeeRepository(empList); + + @After + public void cleanup() throws IOException { + Files.deleteIfExists(Paths.get(fileName)); + } + + @Test + public void whenGetStreamFromList_ObtainStream() { + assert(empList.stream() instanceof Stream); + } + + @Test + public void whenGetStreamFromArray_ObtainStream() { + assert(Stream.of(arrayOfEmps) instanceof Stream); + } + + @Test + public void whenGetStreamFromElements_ObtainStream() { + assert(Stream.of(arrayOfEmps[0], arrayOfEmps[1], arrayOfEmps[2]) instanceof Stream); + } + + @Test + public void whenBuildStreamFromElements_ObtainStream() { + Stream.Builder empStreamBuilder = Stream.builder(); + + empStreamBuilder.accept(arrayOfEmps[0]); + empStreamBuilder.accept(arrayOfEmps[1]); + empStreamBuilder.accept(arrayOfEmps[2]); + + Stream empStream = empStreamBuilder.build(); + + assert(empStream instanceof Stream); + } + + @Test + public void whenIncrementSalaryForEachEmployee_thenApplyNewSalary() { + Employee[] arrayOfEmps = { + new Employee(1, "Jeff Bezos", 100000.0), + new Employee(2, "Bill Gates", 200000.0), + new Employee(3, "Mark Zuckerberg", 300000.0) + }; + + List empList = Arrays.asList(arrayOfEmps); + + empList.stream().forEach(e -> e.salaryIncrement(10.0)); + + assertThat(empList, contains( + hasProperty("salary", equalTo(110000.0)), + hasProperty("salary", equalTo(220000.0)), + hasProperty("salary", equalTo(330000.0)) + )); + } + + @Test + public void whenIncrementSalaryUsingPeek_thenApplyNewSalary() { + Employee[] arrayOfEmps = { + new Employee(1, "Jeff Bezos", 100000.0), + new Employee(2, "Bill Gates", 200000.0), + new Employee(3, "Mark Zuckerberg", 300000.0) + }; + + List empList = Arrays.asList(arrayOfEmps); + + empList.stream() + .peek(e -> e.salaryIncrement(10.0)) + .peek(System.out::println) + .collect(Collectors.toList()); + + assertThat(empList, contains( + hasProperty("salary", equalTo(110000.0)), + hasProperty("salary", equalTo(220000.0)), + hasProperty("salary", equalTo(330000.0)) + )); + } + + @Test + public void whenMapIdToEmployees_thenGetEmployeeStream() { + Integer[] empIds = { 1, 2, 3 }; + + List employees = Stream.of(empIds) + .map(employeeRepository::findById) + .collect(Collectors.toList()); + + assertEquals(employees.size(), empIds.length); + } + + @Test + public void whenFlatMapEmployeeNames_thenGetNameStream() { + List> namesNested = Arrays.asList( + Arrays.asList("Jeff", "Bezos"), + Arrays.asList("Bill", "Gates"), + Arrays.asList("Mark", "Zuckerberg")); + + List namesFlatStream = namesNested.stream() + .flatMap(Collection::stream) + .collect(Collectors.toList()); + + assertEquals(namesFlatStream.size(), namesNested.size() * 2); + } + + @Test + public void whenFilterEmployees_thenGetFilteredStream() { + Integer[] empIds = { 1, 2, 3, 4 }; + + List employees = Stream.of(empIds) + .map(employeeRepository::findById) + .filter(e -> e != null) + .filter(e -> e.getSalary() > 200000) + .collect(Collectors.toList()); + + assertEquals(Arrays.asList(arrayOfEmps[2]), employees); + } + + @Test + public void whenFindFirst_thenGetFirstEmployeeInStream() { + Integer[] empIds = { 1, 2, 3, 4 }; + + Employee employee = Stream.of(empIds) + .map(employeeRepository::findById) + .filter(e -> e != null) + .filter(e -> e.getSalary() > 100000) + .findFirst() + .orElse(null); + + assertEquals(employee.getSalary(), new Double(200000)); + } + + @Test + public void whenCollectStreamToList_thenGetList() { + List employees = empList.stream().collect(Collectors.toList()); + + assertEquals(empList, employees); + } + + @Test + public void whenStreamToArray_thenGetArray() { + Employee[] employees = empList.stream().toArray(Employee[]::new); + + assertThat(empList.toArray(), equalTo(employees)); + } + + @Test + public void whenStreamCount_thenGetElementCount() { + Long empCount = empList.stream() + .filter(e -> e.getSalary() > 200000) + .count(); + + assertEquals(empCount, new Long(1)); + } + + @Test + public void whenLimitInfiniteStream_thenGetFiniteElements() { + Stream infiniteStream = Stream.iterate(2, i -> i * 2); + + List collect = infiniteStream + .skip(3) + .limit(5) + .collect(Collectors.toList()); + + assertEquals(collect, Arrays.asList(16, 32, 64, 128, 256)); + } + + @Test + public void whenSortStream_thenGetSortedStream() { + List employees = empList.stream() + .sorted((e1, e2) -> e1.getName().compareTo(e2.getName())) + .collect(Collectors.toList()); + + assertEquals(employees.get(0).getName(), "Bill Gates"); + assertEquals(employees.get(1).getName(), "Jeff Bezos"); + assertEquals(employees.get(2).getName(), "Mark Zuckerberg"); + } + + + @Test + public void whenFindMin_thenGetMinElementFromStream() { + Employee firstEmp = empList.stream() + .min((e1, e2) -> e1.getId() - e2.getId()) + .orElseThrow(NoSuchElementException::new); + + assertEquals(firstEmp.getId(), new Integer(1)); + } + + @Test + public void whenFindMax_thenGetMaxElementFromStream() { + Employee maxSalEmp = empList.stream() + .max(Comparator.comparing(Employee::getSalary)) + .orElseThrow(NoSuchElementException::new); + + assertEquals(maxSalEmp.getSalary(), new Double(300000.0)); + } + + @Test + public void whenApplyDistinct_thenRemoveDuplicatesFromStream() { + List intList = Arrays.asList(2, 5, 3, 2, 4, 3); + List distinctIntList = intList.stream().distinct().collect(Collectors.toList()); + + assertEquals(distinctIntList, Arrays.asList(2, 5, 3, 4)); + } + + @Test + public void whenApplyMatch_thenReturnBoolean() { + List intList = Arrays.asList(2, 4, 5, 6, 8); + + boolean allEven = intList.stream().allMatch(i -> i % 2 == 0); + boolean oneEven = intList.stream().anyMatch(i -> i % 2 == 0); + boolean noneMultipleOfThree = intList.stream().noneMatch(i -> i % 3 == 0); + + assertEquals(allEven, false); + assertEquals(oneEven, true); + assertEquals(noneMultipleOfThree, false); + } + + @Test + public void whenFindMaxOnIntStream_thenGetMaxInteger() { + Integer latestEmpId = empList.stream() + .mapToInt(Employee::getId) + .max() + .orElseThrow(NoSuchElementException::new); + + assertEquals(latestEmpId, new Integer(3)); + } + + @Test + public void whenApplySumOnIntStream_thenGetSum() { + Double avgSal = empList.stream() + .mapToDouble(Employee::getSalary) + .average() + .orElseThrow(NoSuchElementException::new); + + assertEquals(avgSal, new Double(200000)); + } + + @Test + public void whenApplyReduceOnStream_thenGetValue() { + Double sumSal = empList.stream() + .map(Employee::getSalary) + .reduce(0.0, Double::sum); + + assertEquals(sumSal, new Double(600000)); + } + + @Test + public void whenCollectByJoining_thenGetJoinedString() { + String empNames = empList.stream() + .map(Employee::getName) + .collect(Collectors.joining(", ")) + .toString(); + + assertEquals(empNames, "Jeff Bezos, Bill Gates, Mark Zuckerberg"); + } + + @Test + public void whenCollectBySet_thenGetSet() { + Set empNames = empList.stream() + .map(Employee::getName) + .collect(Collectors.toSet()); + + assertEquals(empNames.size(), 3); + } + + @Test + public void whenToVectorCollection_thenGetVector() { + Vector empNames = empList.stream() + .map(Employee::getName) + .collect(Collectors.toCollection(Vector::new)); + + assertEquals(empNames.size(), 3); + } + + @Test + public void whenApplySummarizing_thenGetBasicStats() { + DoubleSummaryStatistics stats = empList.stream() + .collect(Collectors.summarizingDouble(Employee::getSalary)); + + assertEquals(stats.getCount(), 3); + assertEquals(stats.getSum(), 600000.0, 0); + assertEquals(stats.getMin(), 100000.0, 0); + assertEquals(stats.getMax(), 300000.0, 0); + assertEquals(stats.getAverage(), 200000.0, 0); + } + + @Test + public void whenApplySummaryStatistics_thenGetBasicStats() { + DoubleSummaryStatistics stats = empList.stream() + .mapToDouble(Employee::getSalary) + .summaryStatistics(); + + assertEquals(stats.getCount(), 3); + assertEquals(stats.getSum(), 600000.0, 0); + assertEquals(stats.getMin(), 100000.0, 0); + assertEquals(stats.getMax(), 300000.0, 0); + assertEquals(stats.getAverage(), 200000.0, 0); + } + + @Test + public void whenStreamPartition_thenGetMap() { + List intList = Arrays.asList(2, 4, 5, 6, 8); + Map> isEven = intList.stream().collect( + Collectors.partitioningBy(i -> i % 2 == 0)); + + assertEquals(isEven.get(true).size(), 4); + assertEquals(isEven.get(false).size(), 1); + } + + @Test + public void whenStreamGroupingBy_thenGetMap() { + Map> groupByAlphabet = empList.stream().collect( + Collectors.groupingBy(e -> new Character(e.getName().charAt(0)))); + + assertEquals(groupByAlphabet.get('B').get(0).getName(), "Bill Gates"); + assertEquals(groupByAlphabet.get('J').get(0).getName(), "Jeff Bezos"); + assertEquals(groupByAlphabet.get('M').get(0).getName(), "Mark Zuckerberg"); + } + + @Test + public void whenStreamMapping_thenGetMap() { + Map> idGroupedByAlphabet = empList.stream().collect( + Collectors.groupingBy(e -> new Character(e.getName().charAt(0)), + Collectors.mapping(Employee::getId, Collectors.toList()))); + + assertEquals(idGroupedByAlphabet.get('B').get(0), new Integer(2)); + assertEquals(idGroupedByAlphabet.get('J').get(0), new Integer(1)); + assertEquals(idGroupedByAlphabet.get('M').get(0), new Integer(3)); + } + + @Test + public void whenStreamReducing_thenGetValue() { + Double percentage = 10.0; + Double salIncrOverhead = empList.stream().collect(Collectors.reducing( + 0.0, e -> e.getSalary() * percentage / 100, (s1, s2) -> s1 + s2)); + + assertEquals(salIncrOverhead, 60000.0, 0); + } + + @Test + public void whenStreamGroupingAndReducing_thenGetMap() { + Comparator byNameLength = Comparator.comparing(Employee::getName); + + Map> longestNameByAlphabet = empList.stream().collect( + Collectors.groupingBy(e -> new Character(e.getName().charAt(0)), + Collectors.reducing(BinaryOperator.maxBy(byNameLength)))); + + assertEquals(longestNameByAlphabet.get('B').get().getName(), "Bill Gates"); + assertEquals(longestNameByAlphabet.get('J').get().getName(), "Jeff Bezos"); + assertEquals(longestNameByAlphabet.get('M').get().getName(), "Mark Zuckerberg"); + } + + @Test + public void whenParallelStream_thenPerformOperationsInParallel() { + Employee[] arrayOfEmps = { + new Employee(1, "Jeff Bezos", 100000.0), + new Employee(2, "Bill Gates", 200000.0), + new Employee(3, "Mark Zuckerberg", 300000.0) + }; + + List empList = Arrays.asList(arrayOfEmps); + + empList.stream().parallel().forEach(e -> e.salaryIncrement(10.0)); + + assertThat(empList, contains( + hasProperty("salary", equalTo(110000.0)), + hasProperty("salary", equalTo(220000.0)), + hasProperty("salary", equalTo(330000.0)) + )); + } + + @Test + public void whenGenerateStream_thenGetInfiniteStream() { + Stream.generate(Math::random) + .limit(5) + .forEach(System.out::println); + } + + @Test + public void whenIterateStream_thenGetInfiniteStream() { + Stream evenNumStream = Stream.iterate(2, i -> i * 2); + + List collect = evenNumStream + .limit(5) + .collect(Collectors.toList()); + + assertEquals(collect, Arrays.asList(2, 4, 8, 16, 32)); + } + + @Test + public void whenStreamToFile_thenGetFile() throws IOException { + String[] words = { + "hello", + "refer", + "world", + "level" + }; + + try (PrintWriter pw = new PrintWriter( + Files.newBufferedWriter(Paths.get(fileName)))) { + Stream.of(words).forEach(pw::println); + } + } + + private List getPalindrome(Stream stream, int length) { + return stream.filter(s -> s.length() == length) + .filter(s -> s.compareToIgnoreCase( + new StringBuilder(s).reverse().toString()) == 0) + .collect(Collectors.toList()); + } + + @Test + public void whenFileToStream_thenGetStream() throws IOException { + whenStreamToFile_thenGetFile(); + + List str = getPalindrome(Files.lines(Paths.get(fileName)), 5); + assertThat(str, contains("refer", "level")); + } +} diff --git a/guest/core-java/src/test/resources/.keep b/guest/core-java/src/test/resources/.keep new file mode 100644 index 0000000000..e69de29bb2