[BAEL-9555] - Created a core-java-modules folder

core-java-modules/core-java-12/src/test/java/com/baeldung/collectors/CollectorsUnitTest.java

@@ -0,0 +1,71 @@
+package com.baeldung.collectors;
+
+import java.util.Arrays;
+import java.util.List;
+import java.util.Objects;
+
+import org.junit.Test;
+
+import static java.util.stream.Collectors.maxBy;
+import static java.util.stream.Collectors.minBy;
+import static java.util.stream.Collectors.teeing;
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for collectors additions in Java 12.
+ */
+public class CollectorsUnitTest {
+
+    @Test
+    public void whenTeeing_ItShouldCombineTheResultsAsExpected() {
+        List<Integer> numbers = Arrays.asList(42, 4, 2, 24);
+        Range range = numbers.stream()
+            .collect(teeing(minBy(Integer::compareTo), maxBy(Integer::compareTo), (min, max) -> new Range(min.orElse(null), max.orElse(null))));
+
+        assertThat(range).isEqualTo(new Range(2, 42));
+    }
+
+    /**
+     * Represents a closed range of numbers between {@link #min} and
+     * {@link #max}, both inclusive.
+     */
+    private static class Range {
+
+        private final Integer min;
+
+        private final Integer max;
+
+        Range(Integer min, Integer max) {
+            this.min = min;
+            this.max = max;
+        }
+
+        Integer getMin() {
+            return min;
+        }
+
+        Integer getMax() {
+            return max;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o)
+                return true;
+            if (o == null || getClass() != o.getClass())
+                return false;
+            Range range = (Range) o;
+            return Objects.equals(getMin(), range.getMin()) && Objects.equals(getMax(), range.getMax());
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(getMin(), getMax());
+        }
+
+        @Override
+        public String toString() {
+            return "Range{" + "min=" + min + ", max=" + max + '}';
+        }
+    }
+}

core-java-modules/core-java-12/src/test/java/com/baeldung/switchExpression/SwitchUnitTest.java

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+package com.baeldung.switchExpression;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class SwitchUnitTest {
+
+    @Test
+    public void switchJava12(){
+
+        var month = Month.AUG;
+
+        var value = switch(month){
+            case JAN,JUN, JUL -> 3;
+            case FEB,SEP, OCT, NOV, DEC -> 1;
+            case MAR,MAY, APR, AUG -> 2;
+        };
+
+        Assert.assertEquals(value, 2);
+    }
+
+    @Test
+    public void switchLocalVariable(){
+        var month = Month.AUG;
+        int i = switch (month){
+            case JAN,JUN, JUL -> 3;
+            case FEB,SEP, OCT, NOV, DEC -> 1;
+            case MAR,MAY, APR, AUG -> {
+                int j = month.toString().length() * 4;
+                break j;
+            }
+        };
+        Assert.assertEquals(12, i);
+    }
+
+    enum Month {JAN, FEB, MAR, APR, MAY, JUN, JUL, AUG, SEP, OCT, NOV, DEC}
+}