BAEL-7862: Float conversion tests (#16506)

* BAEL-7862: Float conversion tests

* BAEL-7862: Float Collector

core-java-modules/core-java-collections-conversions-3/pom.xml

@@ -13,6 +13,14 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>${apache.commons.version}</version>
+        </dependency>
+    </dependencies>
+
     <build>
         <finalName>core-java-collections-conversions-3</finalName>
         <resources>
@@ -23,4 +31,8 @@
         </resources>
     </build>
 
+    <properties>
+        <apache.commons.version>3.14.0</apache.commons.version>
+    </properties>
+
 </project>

core-java-modules/core-java-collections-conversions-3/src/test/java/com/baeldung/listtoprimitivearray/ConvertingListToPrimitiveArrayUnitTest.java

@@ -0,0 +1,104 @@
+package com.baeldung.listtoprimitivearray;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+class ConvertingListToPrimitiveArrayUnitTest {
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertToWrapperArray_thenGetCorrectResult(List<Float> floats) {
+        Float[] actual = floats.toArray(new Float[0]);
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertToWrapperArrayWithPreSizedArray_thenGetCorrectResult(List<Float> floats) {
+        Float[] actual = floats.toArray(new Float[floats.size()]);
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertToPrimitiveArray_thenGetCorrectResult(List<Float> floats) {
+        float[] actual = new float[floats.size()];
+        for (int i = 0; i < floats.size(); i++) {
+            actual[i] = floats.get(i);
+        }
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenUnboxToPrimitiveArray_thenGetCorrectResult(List<Float> floats) {
+        float[] actual = new float[floats.size()];
+        Float[] floatArray = floats.toArray(new Float[0]);
+        for (int i = 0; i < floats.size(); i++) {
+            actual[i] = floatArray[i];
+        }
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertToPrimitiveArrayWithArrayUtils_thenGetCorrectResult(List<Float> floats) {
+        float[] actual = ArrayUtils.toPrimitive(floats.toArray(new Float[]{}));
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertingToPrimitiveArrayUsingStreams_thenGetCorrectResult(List<Float> floats) {
+        double[] actual = floats.stream().mapToDouble(Float::doubleValue).toArray();
+        assertSequences(floats, actual);
+    }
+
+    @ParameterizedTest
+    @MethodSource("floatListProvider")
+    void givenListOfWrapperFloat_whenConvertingWithCollector_thenGetCorrectResult(List<Float> floats) {
+        float[] actual = floats.stream().collect(new FloatCollector(floats.size()));
+        assertSequences(floats, actual);
+    }
+
+    private static void assertSequences(Iterable<Float> floats, Float[] actual) {
+        assertThat(actual).hasSameSizeAs(floats);
+        for (Float value : floats) {
+            assertThat(actual).contains(value);
+        }
+    }
+
+    private static void assertSequences(Iterable<Float> floats, float[] actual) {
+        assertThat(actual).hasSameSizeAs(floats);
+        for (Float value : floats) {
+            assertThat(actual).contains(value);
+        }
+    }
+
+    private static void assertSequences(Iterable<Float> floats, double[] actual) {
+        assertThat(actual).hasSameSizeAs(floats);
+        for (Float value : floats) {
+            assertThat(actual).contains(value);
+        }
+    }
+
+    static Stream<List<Float>> floatListProvider() {
+        ArrayList<Float> floats = new ArrayList<>();
+        floats.add(Float.valueOf(131.36f));
+        floats.add(Float.valueOf(66.59f));
+        floats.add(Float.valueOf(58.03f));
+        floats.add(Float.valueOf(951.56f));
+        floats.add(Float.valueOf(192.04f));
+        floats.add(Float.valueOf(899.03f));
+        floats.add(Float.valueOf(147.32f));
+        floats.add(Float.valueOf(573.75f));
+        floats.add(Float.valueOf(94.75f));
+        return Stream.of(floats);
+    }
+}

core-java-modules/core-java-collections-conversions-3/src/test/java/com/baeldung/listtoprimitivearray/FloatCollector.java

@@ -0,0 +1,47 @@
+package com.baeldung.listtoprimitivearray;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Set;
+import java.util.function.BiConsumer;
+import java.util.function.BinaryOperator;
+import java.util.function.Function;
+import java.util.function.Supplier;
+import java.util.stream.Collector;
+
+public class FloatCollector implements Collector<Float, float[], float[]> {
+
+    private final int size;
+    private int index = 0;
+    public FloatCollector(int size) {
+        this.size = size;
+    }
+
+    @Override
+    public Supplier<float[]> supplier() {
+        return () -> new float[size];
+    }
+
+    @Override
+    public BiConsumer<float[], Float> accumulator() {
+        return (array, number) -> {
+            array[index] = number;
+            index++;
+        };
+    }
+
+    @Override
+    public BinaryOperator<float[]> combiner() {
+        return null;
+    }
+
+    @Override
+    public Function<float[], float[]> finisher() {
+        return Function.identity();
+    }
+
+    @Override
+    public Set<Characteristics> characteristics() {
+        return Collections.emptySet();
+    }
+}