Merge branch 'master' into BAEL-16633

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/Java9OptionalsStreamUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.java9;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+public class Java9OptionalsStreamUnitTest {
+
+    private static List<Optional<String>> listOfOptionals = Arrays.asList(Optional.empty(), Optional.of("foo"), Optional.empty(), Optional.of("bar"));
+
+    @Test
+    public void filterOutPresentOptionalsWithFilter() {
+        assertEquals(4, listOfOptionals.size());
+
+        List<String> filteredList = listOfOptionals.stream().filter(Optional::isPresent).map(Optional::get).collect(Collectors.toList());
+
+        assertEquals(2, filteredList.size());
+        assertEquals("foo", filteredList.get(0));
+        assertEquals("bar", filteredList.get(1));
+    }
+
+    @Test
+    public void filterOutPresentOptionalsWithFlatMap() {
+        assertEquals(4, listOfOptionals.size());
+
+        List<String> filteredList = listOfOptionals.stream().flatMap(o -> o.isPresent() ? Stream.of(o.get()) : Stream.empty()).collect(Collectors.toList());
+        assertEquals(2, filteredList.size());
+
+        assertEquals("foo", filteredList.get(0));
+        assertEquals("bar", filteredList.get(1));
+    }
+
+    @Test
+    public void filterOutPresentOptionalsWithFlatMap2() {
+        assertEquals(4, listOfOptionals.size());
+
+        List<String> filteredList = listOfOptionals.stream().flatMap(o -> o.map(Stream::of).orElseGet(Stream::empty)).collect(Collectors.toList());
+        assertEquals(2, filteredList.size());
+
+        assertEquals("foo", filteredList.get(0));
+        assertEquals("bar", filteredList.get(1));
+    }
+
+    @Test
+    public void filterOutPresentOptionalsWithJava9() {
+        assertEquals(4, listOfOptionals.size());
+
+        List<String> filteredList = listOfOptionals.stream().flatMap(Optional::stream).collect(Collectors.toList());
+
+        assertEquals(2, filteredList.size());
+        assertEquals("foo", filteredList.get(0));
+        assertEquals("bar", filteredList.get(1));
+    }
+
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/SetExamplesUnitTest.java

@@ -0,0 +1,38 @@
+package com.baeldung.java9;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class SetExamplesUnitTest {
+
+    @Test
+    public void testUnmutableSet() {
+        Set<String> strKeySet = Set.of("key1", "key2", "key3");
+        try {
+            strKeySet.add("newKey");
+        } catch (UnsupportedOperationException uoe) {
+        }
+        assertEquals(strKeySet.size(), 3);
+    }
+
+    @Test
+    public void testArrayToSet() {
+        Integer[] intArray = new Integer[] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 0 };
+        Set<Integer> intSet = Set.of(intArray);
+        assertEquals(intSet.size(), intArray.length);
+    }
+
+    @Test(expected = UnsupportedOperationException.class)
+    public void testUnmodifiableSet() {
+        Set<String> set = new HashSet<>();
+        set.add("Canada");
+        set.add("USA");
+
+        Set<String> unmodifiableSet = Collections.unmodifiableSet(set);
+        unmodifiableSet.add("Costa Rica");
+    }
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/language/stream/CollectionFilterUnitTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.java9.language.stream;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+import org.junit.platform.runner.JUnitPlatform;
+import org.junit.runner.RunWith;
+
+@RunWith(JUnitPlatform.class)
+public class CollectionFilterUnitTest {
+
+    private static final Collection<Integer> BASE_INTEGER_COLLECTION = Arrays.asList(9, 12, 55, 56, 101, 115, 8002, 223, 2668, 19, 8);
+    private static final Map<Integer, List<Integer>> EXPECTED_EVEN_FILTERED_AFTER_GROUPING_MAP = createExpectedFilterAfterGroupingMap();
+    private static Map<Integer, List<Integer>> createExpectedFilterAfterGroupingMap() {
+        Map<Integer, List<Integer>> map = new HashMap<>();
+        map.put(1, Arrays.asList(8));
+        map.put(2, Arrays.asList(12, 56));
+        map.put(3, Collections.emptyList());
+        map.put(4, Arrays.asList(8002, 2668));
+        return map;
+
+    }
+
+    private static final Map<Integer, List<Integer>> EXPECTED_EVEN_FILTERED_BEFORE_GROUPING_MAP = createExpectedFilterBeforeGroupingMap();
+    private static Map<Integer, List<Integer>> createExpectedFilterBeforeGroupingMap() {
+        Map<Integer, List<Integer>> map = new HashMap<>();
+        map.put(1, Arrays.asList(8));
+        map.put(2, Arrays.asList(12, 56));
+        map.put(4, Arrays.asList(8002, 2668));
+        return map;
+
+    }
+
+    @Test
+    public void givenAStringCollection_whenFilteringFourLetterWords_thenObtainTheFilteredCollection() {
+        Map<Integer, List<Integer>> filteredAfterGroupingMap = StreamsGroupingCollectionFilter.findEvenNumbersAfterGroupingByQuantityOfDigits(BASE_INTEGER_COLLECTION);
+        Map<Integer, List<Integer>> filteredBeforeGroupingMap = StreamsGroupingCollectionFilter.findEvenNumbersBeforeGroupingByQuantityOfDigits(BASE_INTEGER_COLLECTION);
+
+        assertThat(filteredAfterGroupingMap).containsAllEntriesOf(EXPECTED_EVEN_FILTERED_AFTER_GROUPING_MAP);
+        assertThat(filteredBeforeGroupingMap).doesNotContainKey(3)
+            .containsAllEntriesOf(EXPECTED_EVEN_FILTERED_BEFORE_GROUPING_MAP);
+    }
+
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/methodhandles/MethodHandlesTest.java

@@ -0,0 +1,152 @@
+package com.baeldung.java9.methodhandles;
+
+import static org.hamcrest.CoreMatchers.is;
+import static org.junit.Assert.*;
+
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.MethodType;
+import java.lang.invoke.WrongMethodTypeException;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.Test;
+
+/**
+ * Test case for the {@link MethodHandles} API
+ */
+public class MethodHandlesTest {
+
+    @Test
+    public void givenConcatMethodHandle_whenInvoked_thenCorrectlyConcatenated() throws Throwable {
+
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, String.class);
+        MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
+
+        String output = (String) concatMH.invoke("Effective ", "Java");
+
+        assertEquals("Effective Java", output);
+    }
+
+    @Test
+    public void givenAsListMethodHandle_whenInvokingWithArguments_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(List.class, Object[].class);
+        MethodHandle asListMH = publicLookup.findStatic(Arrays.class, "asList", mt);
+
+        List<Integer> list = (List<Integer>) asListMH.invokeWithArguments(1, 2);
+
+        assertThat(Arrays.asList(1, 2), is(list));
+    }
+
+    @Test
+    public void givenConstructorMethodHandle_whenInvoked_thenObjectCreatedCorrectly() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(void.class, String.class);
+        MethodHandle newIntegerMH = publicLookup.findConstructor(Integer.class, mt);
+
+        Integer integer = (Integer) newIntegerMH.invoke("1");
+
+        assertEquals(1, integer.intValue());
+    }
+
+    @Test
+    public void givenAFieldWithoutGetter_whenCreatingAGetter_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodHandle getTitleMH = lookup.findGetter(Book.class, "title", String.class);
+
+        Book book = new Book("ISBN-1234", "Effective Java");
+
+        assertEquals("Effective Java", getTitleMH.invoke(book));
+    }
+
+    @Test
+    public void givenPrivateMethod_whenCreatingItsMethodHandle_thenCorrectlyInvoked() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        Method formatBookMethod = Book.class.getDeclaredMethod("formatBook");
+        formatBookMethod.setAccessible(true);
+
+        MethodHandle formatBookMH = lookup.unreflect(formatBookMethod);
+
+        Book book = new Book("ISBN-123", "Java in Action");
+
+        assertEquals("ISBN-123 > Java in Action", formatBookMH.invoke(book));
+    }
+
+    @Test
+    public void givenReplaceMethod_whenUsingReflectionAndInvoked_thenCorrectlyReplaced() throws Throwable {
+        Method replaceMethod = String.class.getMethod("replace", char.class, char.class);
+
+        String string = (String) replaceMethod.invoke("jovo", 'o', 'a');
+
+        assertEquals("java", string);
+    }
+
+    @Test
+    public void givenReplaceMethodHandle_whenInvoked_thenCorrectlyReplaced() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, char.class, char.class);
+        MethodHandle replaceMH = publicLookup.findVirtual(String.class, "replace", mt);
+
+        String replacedString = (String) replaceMH.invoke("jovo", Character.valueOf('o'), 'a');
+
+        assertEquals("java", replacedString);
+    }
+
+    @Test
+    public void givenReplaceMethodHandle_whenInvokingExact_thenCorrectlyReplaced() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(String.class, char.class, char.class);
+        MethodHandle replaceMH = lookup.findVirtual(String.class, "replace", mt);
+
+        String s = (String) replaceMH.invokeExact("jovo", 'o', 'a');
+
+        assertEquals("java", s);
+    }
+
+    @Test
+    public void givenSumMethodHandle_whenInvokingExact_thenSumIsCorrect() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(int.class, int.class, int.class);
+        MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
+
+        int sum = (int) sumMH.invokeExact(1, 11);
+
+        assertEquals(12, sum);
+    }
+
+    @Test(expected = WrongMethodTypeException.class)
+    public void givenSumMethodHandleAndIncompatibleArguments_whenInvokingExact_thenException() throws Throwable {
+        MethodHandles.Lookup lookup = MethodHandles.lookup();
+        MethodType mt = MethodType.methodType(int.class, int.class, int.class);
+        MethodHandle sumMH = lookup.findStatic(Integer.class, "sum", mt);
+
+        sumMH.invokeExact(Integer.valueOf(1), 11);
+    }
+
+    @Test
+    public void givenSpreadedEqualsMethodHandle_whenInvokedOnArray_thenCorrectlyEvaluated() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(boolean.class, Object.class);
+        MethodHandle equalsMH = publicLookup.findVirtual(String.class, "equals", mt);
+
+        MethodHandle methodHandle = equalsMH.asSpreader(Object[].class, 2);
+
+        assertTrue((boolean) methodHandle.invoke(new Object[] { "java", "java" }));
+        assertFalse((boolean) methodHandle.invoke(new Object[] { "java", "jova" }));
+    }
+
+    @Test
+    public void givenConcatMethodHandle_whenBindToAString_thenCorrectlyConcatenated() throws Throwable {
+        MethodHandles.Lookup publicLookup = MethodHandles.publicLookup();
+        MethodType mt = MethodType.methodType(String.class, String.class);
+        MethodHandle concatMH = publicLookup.findVirtual(String.class, "concat", mt);
+
+        MethodHandle bindedConcatMH = concatMH.bindTo("Hello ");
+
+        assertEquals("Hello World!", bindedConcatMH.invoke("World!"));
+    }
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/rangedates/DatesCollectionIterationUnitTest.java

@@ -0,0 +1,61 @@
+package com.baeldung.java9.rangedates;
+
+import java.time.LocalDate;
+import java.time.ZoneId;
+import java.time.temporal.ChronoUnit;
+import java.util.ArrayList;
+import java.util.Calendar;
+import java.util.Collection;
+import java.util.Date;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import org.junit.Test;
+
+public class DatesCollectionIterationUnitTest {
+
+    private Collection<LocalDate> localDates = LocalDate.now()
+        .datesUntil(LocalDate.now()
+            .plus(10L, ChronoUnit.DAYS))
+        .collect(Collectors.toList());
+
+    private Collection<Date> dates = localDates.stream()
+        .map(localDate -> Date.from(localDate.atStartOfDay(ZoneId.systemDefault())
+            .toInstant()))
+        .collect(Collectors.toList());
+
+    @Test
+    public void givenIteratingListOfDatesJava7_WhenStartTodayAndEnding10DaysAhead() {
+        DatesCollectionIteration iterateInColleciton = new DatesCollectionIteration();
+        Calendar today = Calendar.getInstance();
+        Calendar next10Ahead = (Calendar) today.clone();
+        next10Ahead.add(Calendar.DATE, 10);
+
+        iterateInColleciton.iteratingRangeOfDatesJava7(createRangeDates(today.getTime(), next10Ahead.getTime()));
+    }
+
+    @Test
+    public void givenIteratingListOfDatesJava8_WhenStartTodayAndEnd10DaysAhead() {
+        DatesCollectionIteration iterateInColleciton = new DatesCollectionIteration();
+
+        iterateInColleciton.iteratingRangeOfDatesJava8(dates);
+    }
+
+    private List<Date> createRangeDates(Date start, Date end) {
+
+        List<Date> dates = new ArrayList<>();
+        Date current = start;
+
+        while (current.before(end)) {
+            dates.add(current);
+            
+            Calendar calendar = Calendar.getInstance();
+            calendar.setTime(current);
+            calendar.add(Calendar.DATE, 1);
+
+            current = calendar.getTime();
+        }
+
+        return dates;
+    }
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/java9/rangedates/RangeDatesIterationUnitTest.java

@@ -0,0 +1,48 @@
+package com.baeldung.java9.rangedates;
+
+import java.time.LocalDate;
+import java.time.temporal.ChronoUnit;
+import java.util.Calendar;
+import java.util.Date;
+
+import org.junit.Test;
+
+public class RangeDatesIterationUnitTest {
+
+    @Test
+    public void givenIterateBetweenDatesJava9_WhenStartDateAsTodayAndEndDateAs10DaysAhead() {
+        LocalDate start = LocalDate.now();
+        LocalDate end = start.plus(10L, ChronoUnit.DAYS);
+
+        RangeDatesIteration iteration = new RangeDatesIteration();
+
+        iteration.iterateBetweenDatesJava9(start, end);
+    }
+
+    @Test
+    public void givenIterateBetweenDatesJava8_WhenStartDateAsTodayAndEndDateAs10DaysAhead() {
+        LocalDate start = LocalDate.now();
+        LocalDate end = start.plus(10L, ChronoUnit.DAYS);
+
+        RangeDatesIteration iteration = new RangeDatesIteration();
+
+        iteration.iterateBetweenDatesJava8(start, end);
+    }
+
+    @Test
+    public void givenIterateBetweenDatesJava7_WhenStartDateAsTodayAndEndDateAs10DaysAhead() {
+        Calendar today = Calendar.getInstance();
+        Calendar calendar = Calendar.getInstance();
+        calendar.clear();
+        calendar.set(today.get(Calendar.YEAR), today.get(Calendar.MONTH), today.get(Calendar.DATE));
+        Date start = calendar.getTime();
+
+        calendar.add(Calendar.DATE, 10);
+        Date end = calendar.getTime();
+
+        RangeDatesIteration iteration = new RangeDatesIteration();
+
+        iteration.iterateBetweenDatesJava7(start, end);
+    }
+
+}

core-java-modules/core-java-9/src/test/java/com/baeldung/optionals/OptionalsTest.java

@@ -0,0 +1,51 @@
+package com.baeldung.optionals;
+
+import static org.junit.Assert.assertEquals;
+
+import java.util.Optional;
+
+import org.junit.Test;
+
+public class OptionalsTest {
+
+    @Test
+    public void givenOptional_whenEmptyValue_thenCustomMessage() {
+        assertEquals(Optional.of("Name not provided"), Optionals.getName(Optional.ofNullable(null)));
+    }
+
+    @Test
+    public void givenOptional_whenValue_thenOptional() {
+        String name = "Filan Fisteku";
+        Optional<String> optionalString = Optional.ofNullable(name);
+        assertEquals(optionalString, Optionals.getName(optionalString));
+    }
+    
+    @Test
+    public void givenOptional_whenValue_thenOptionalGeneralMethod() {
+        String name = "Filan Fisteku";
+        String missingOptional = "Name not provided";
+        Optional<String> optionalString = Optional.ofNullable(name);
+        Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
+        assertEquals(optionalString, Optionals.or(optionalString, fallbackOptionalString));
+    }
+    
+    @Test
+    public void givenEmptyOptional_whenValue_thenOptionalGeneralMethod() {
+        String missingOptional = "Name not provided";
+        Optional<String> optionalString = Optional.empty();
+        Optional<String> fallbackOptionalString = Optional.ofNullable(missingOptional);
+        assertEquals(fallbackOptionalString, Optionals.or(optionalString, fallbackOptionalString));
+    }
+
+    @Test
+    public void givenGuavaOptional_whenInvoke_thenOptional() {
+        String name = "Filan Fisteku";
+        com.google.common.base.Optional<String> stringOptional = com.google.common.base.Optional.of(name);
+        assertEquals(stringOptional, Optionals.getOptionalGuavaName(stringOptional));
+    }
+
+    @Test
+    public void givenGuavaOptional_whenNull_thenDefaultText() {
+        assertEquals(com.google.common.base.Optional.of("Name not provided"), Optionals.getOptionalGuavaName(com.google.common.base.Optional.fromNullable(null)));
+    }
+} 

core-java-modules/core-java-9/src/test/resources/.gitignore

@@ -0,0 +1,13 @@
+*.class
+
+#folders#
+/target
+/neoDb*
+/data
+/src/main/webapp/WEB-INF/classes
+*/META-INF/*
+
+# Packaged files #
+*.jar
+*.war
+*.ear