Merge branch 'master' of https://github.com/JonCook/tutorials

core-java-modules/core-java-jvm/README.md

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+=========
+
+## Core Java JVM Cookbooks and Examples
+
+### Relevant Articles: 
+- [Method Inlining in the JVM](https://www.baeldung.com/jvm-method-inlining)
+- [A Guide to System.exit()](https://www.baeldung.com/java-system-exit)
+- [Guide to System.gc()](https://www.baeldung.com/java-system-gc)

core-java-modules/core-java-jvm/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>core-java-jvm</artifactId>
+    <version>0.1.0-SNAPSHOT</version>
+    <packaging>jar</packaging>
+    <name>core-java-jvm</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>parent-modules</artifactId>
+        <version>1.0.0-SNAPSHOT</version>
+        <relativePath>../../</relativePath>
+    </parent>
+
+</project>

core-java-modules/core-java-jvm/src/main/java/com/baeldung/inlining/ConsecutiveNumbersSum.java

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+package com.baeldung.inlining;
+
+public class ConsecutiveNumbersSum {
+
+    private long totalSum;
+    private int totalNumbers;
+
+    public ConsecutiveNumbersSum(int totalNumbers) {
+        this.totalNumbers = totalNumbers;
+    }
+
+    public long getTotalSum() {
+        totalSum = 0;
+        for (int i = 1; i <= totalNumbers; i++) {
+            totalSum += i;
+        }
+        return totalSum;
+    }
+}

core-java-modules/core-java-jvm/src/main/java/com/baeldung/inlining/InliningExample.java

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+package com.baeldung.inlining;
+
+public class InliningExample {
+
+    public static final int NUMBERS_OF_ITERATIONS = 15000;
+
+    public static void main(String[] args) {
+        for (int i = 1; i < NUMBERS_OF_ITERATIONS; i++) {
+            calculateSum(i);
+        }
+    }
+
+    private static long calculateSum(int n) {
+        return new ConsecutiveNumbersSum(n).getTotalSum();
+    }
+}

core-java-modules/core-java-jvm/src/main/java/com/baeldung/systemgc/DemoApplication.java

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+package com.baeldung.systemgc;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Scanner;
+
+import static java.util.UUID.randomUUID;
+
+public class DemoApplication {
+
+    private static final Map<String, String> cache = new HashMap<String, String>();
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        while (scanner.hasNext()) {
+            final String next = scanner.next();
+            if ("fill".equals(next)) {
+                for (int i = 0; i < 1000000; i++) {
+                    cache.put(randomUUID().toString(), randomUUID().toString());
+                }
+            } else if ("invalidate".equals(next)) {
+                cache.clear();
+            } else if ("gc".equals(next)) {
+                System.gc();
+            } else if ("exit".equals(next)) {
+                System.exit(0);
+            } else {
+                System.out.println("unknown");
+            }
+        }
+    }
+}

core-java-modules/core-java-jvm/src/test/java/com/baeldung/inlining/ConsecutiveNumbersSumUnitTest.java

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+package com.baeldung.inlining;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class ConsecutiveNumbersSumUnitTest {
+
+    private static final int TOTAL_NUMBERS = 10;
+
+    @Test
+    public void givenTotalIntegersNumber_whenSumCalculated_thenEquals() {
+        ConsecutiveNumbersSum consecutiveNumbersSum = new ConsecutiveNumbersSum(TOTAL_NUMBERS);
+        long expectedSum = calculateExpectedSum(TOTAL_NUMBERS);
+
+        assertEquals(expectedSum, consecutiveNumbersSum.getTotalSum());
+    }
+
+    private long calculateExpectedSum(int totalNumbers) {
+        return totalNumbers * (totalNumbers + 1) / 2;
+    }
+}