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BAEL-1375 Counter in Java. (#3170)

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* BAEL-1375 Counter in Java.

* BAEL-1375 Frequency counter in java.

* BAEL-1375 Refactored method names.
This commit is contained in:
Muhammed Almas 2017-12-04 01:52:39 +05:30 committed by Grzegorz Piwowarek
parent 41ce086ec6
commit 63d4e7d014
4 changed files with 434 additions and 257 deletions
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18
core-java-8/pom.xml
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@ -83,6 +83,24 @@
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-core</artifactId>
<version>1.19</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-annprocess</artifactId>
<version>1.19</version>
</dependency>
<dependency>
<groupId>org.openjdk.jmh</groupId>
<artifactId>jmh-generator-bytecode</artifactId>
<version>1.19</version>
</dependency>
</dependencies>
<build>

45
core-java-8/src/test/java/com/baeldung/counter/CounterStatistics.java Normal file
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@ -0,0 +1,45 @@
package com.baeldung.counter;
import java.util.HashMap;
import java.util.Map;
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<>();
@Benchmark
public void wrapperAsCounter() {
CounterUtil.counterWithWrapperObject(counterMap);
}
@Benchmark
public void lambdaExpressionWithWrapper() {
CounterUtil.counterWithLambdaAndWrapper(counterWithLongWrapperMap);
}
@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);
}
}

53
core-java-8/src/test/java/com/baeldung/counter/CounterTest.java Normal file
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@ -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 CounterTest {
@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]);
}
}

61
core-java-8/src/test/java/com/baeldung/counter/CounterUtil.java Normal file
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@ -0,0 +1,61 @@
package com.baeldung.counter;
import java.util.Map;
import java.util.stream.Collectors;
import java.util.stream.Stream;
public class CounterUtil {
private final 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) {
counterMap.putAll(Stream.of(COUNTRY_NAMES)
.parallel()
.collect(Collectors.groupingBy(k -> k, 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) {
MutableInteger oldValue = counterMap.get(country);
if (oldValue != null) {
oldValue.increment();
} else {
counterMap.put(country, new MutableInteger(1));
}
}
}
public static void counterWithPrimitiveArray(Map<String, int[]> counterMap) {
for (String country : COUNTRY_NAMES) {
int[] oldCounter = counterMap.get(country);
if (oldCounter != null) {
oldCounter[0] += 1;
} else {
counterMap.put(country, new int[] { 1 });
}
}
}
}