[BAEL-13506] - Split or move core-java-8 module (#7790)

algorithms-miscellaneous-3/README.md

@@ -8,3 +8,4 @@
 - [Checking if a Java Graph has a Cycle](https://www.baeldung.com/java-graph-has-a-cycle)
 - [A Guide to the Folding Technique in Java](https://www.baeldung.com/folding-hashing-technique)
 - [Creating a Triangle with for Loops in Java](https://www.baeldung.com/java-print-triangle)
+- [Efficient Word Frequency Calculator in Java](https://www.baeldung.com/java-word-frequency)

algorithms-miscellaneous-3/pom.xml

@@ -54,6 +54,21 @@
             <version>1.1.0</version>
             <scope>test</scope>
         </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-core</artifactId>
+            <version>${jmh-core.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-annprocess</artifactId>
+            <version>${jmh-generator.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.openjdk.jmh</groupId>
+            <artifactId>jmh-generator-bytecode</artifactId>
+            <version>${jmh-generator.version}</version>
+        </dependency>
     </dependencies>
 
     <build>
@@ -73,5 +88,7 @@
         <commons-collections4.version>4.3</commons-collections4.version>
         <guava.version>28.0-jre</guava.version>
         <retrofit.version>2.6.0</retrofit.version>
+        <jmh-core.version>1.19</jmh-core.version>
+        <jmh-generator.version>1.19</jmh-generator.version>
     </properties>
 </project>

algorithms-miscellaneous-3/src/test/java/com/baeldung/counter/CounterStatistics.java

@@ -0,0 +1,61 @@
+package com.baeldung.counter;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+
+import org.openjdk.jmh.annotations.Benchmark;
+import org.openjdk.jmh.annotations.BenchmarkMode;
+import org.openjdk.jmh.annotations.Fork;
+import org.openjdk.jmh.annotations.Mode;
+
+import com.baeldung.counter.CounterUtil.MutableInteger;
+
+@Fork(value = 1, warmups = 3)
+@BenchmarkMode(Mode.All)
+public class CounterStatistics {
+
+    private static final Map<String, Integer> counterMap = new HashMap<>();
+    private static final Map<String, MutableInteger> counterWithMutableIntMap = new HashMap<>();
+    private static final Map<String, int[]> counterWithIntArrayMap = new HashMap<>();
+    private static final Map<String, Long> counterWithLongWrapperMap = new HashMap<>();
+    private static final Map<String, Long> counterWithLongWrapperStreamMap = new HashMap<>();
+    
+    static {
+        CounterUtil.COUNTRY_NAMES = new String[10000];
+        final String prefix = "NewString"; 
+        Random random = new Random();
+        for (int i=0; i<10000; i++) {
+            CounterUtil.COUNTRY_NAMES[i] = new String(prefix + random.nextInt(1000));
+        }
+    }
+
+  @Benchmark
+    public void wrapperAsCounter() {
+        CounterUtil.counterWithWrapperObject(counterMap);
+    }
+
+    @Benchmark
+    public void lambdaExpressionWithWrapper() {
+        CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
+    }
+    
+    @Benchmark
+    public void parallelStreamWithWrapper() {
+        CounterUtil.counterWithParallelStreamAndWrapper(counterWithLongWrapperStreamMap);
+    }
+
+    @Benchmark
+    public void mutableIntegerAsCounter() {
+        CounterUtil.counterWithMutableInteger(counterWithMutableIntMap);
+    }
+
+    @Benchmark
+    public void primitiveArrayAsCounter() {
+        CounterUtil.counterWithPrimitiveArray(counterWithIntArrayMap);
+    }
+
+    public static void main(String[] args) throws Exception {
+        org.openjdk.jmh.Main.main(args);
+    }
+}

algorithms-miscellaneous-3/src/test/java/com/baeldung/counter/CounterUnitTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.counter;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+
+import com.baeldung.counter.CounterUtil.MutableInteger;
+
+public class CounterUnitTest {
+
+    @Test
+    public void whenMapWithWrapperAsCounter_runsSuccessfully() {
+        Map<String, Integer> counterMap = new HashMap<>();
+        CounterUtil.counterWithWrapperObject(counterMap);
+
+        assertEquals(3, counterMap.get("China")
+            .intValue());
+        assertEquals(2, counterMap.get("India")
+            .intValue());
+    }
+
+    @Test
+    public void whenMapWithLambdaAndWrapperCounter_runsSuccessfully() {
+        Map<String, Long> counterMap = new HashMap<>();
+        CounterUtil.counterWithLambdaAndWrapper(counterMap);
+
+        assertEquals(3l, counterMap.get("China")
+            .longValue());
+        assertEquals(2l, counterMap.get("India")
+            .longValue());
+    }
+
+    @Test
+    public void whenMapWithMutableIntegerCounter_runsSuccessfully() {
+        Map<String, MutableInteger> counterMap = new HashMap<>();
+        CounterUtil.counterWithMutableInteger(counterMap);
+        assertEquals(3, counterMap.get("China")
+            .getCount());
+        assertEquals(2, counterMap.get("India")
+            .getCount());
+    }
+
+    @Test
+    public void whenMapWithPrimitiveArray_runsSuccessfully() {
+        Map<String, int[]> counterMap = new HashMap<>();
+        CounterUtil.counterWithPrimitiveArray(counterMap);
+        assertEquals(3, counterMap.get("China")[0]);
+        assertEquals(2, counterMap.get("India")[0]);
+    }
+}

algorithms-miscellaneous-3/src/test/java/com/baeldung/counter/CounterUtil.java

@@ -0,0 +1,57 @@
+package com.baeldung.counter;
+
+import java.util.Map;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+public class CounterUtil {
+
+    public static String[] COUNTRY_NAMES = { "China", "Australia", "India", "USA", "USSR", "UK", "China", "France", "Poland", "Austria", "India", "USA", "Egypt", "China" };
+
+    public static void counterWithWrapperObject(Map<String, Integer> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            counterMap.compute(country, (k, v) -> v == null ? 1 : v + 1);
+        }
+    }
+
+    public static void counterWithLambdaAndWrapper(Map<String, Long> counterMap) {
+        Stream.of(COUNTRY_NAMES)
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
+    }
+
+    public static void counterWithParallelStreamAndWrapper(Map<String, Long> counterMap) {
+        Stream.of(COUNTRY_NAMES)
+            .parallel()
+            .collect(Collectors.groupingBy(k -> k, () -> counterMap, Collectors.counting()));
+    }
+
+    public static class MutableInteger {
+        int count;
+
+        public MutableInteger(int count) {
+            this.count = count;
+        }
+
+        public void increment() {
+            this.count++;
+        }
+
+        public int getCount() {
+            return this.count;
+        }
+    }
+
+    public static void counterWithMutableInteger(Map<String, MutableInteger> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            counterMap.compute(country, (k, v) -> v == null ? new MutableInteger(0) : v)
+                .increment();
+        }
+    }
+
+    public static void counterWithPrimitiveArray(Map<String, int[]> counterMap) {
+        for (String country : COUNTRY_NAMES) {
+            counterMap.compute(country, (k, v) -> v == null ? new int[] { 0 } : v)[0]++;
+        }
+    }
+
+}