Method inlining example. (#6520)

* Method inlining example.

* Test added

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

@@ -0,0 +1,19 @@
+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/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/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;
+    }
+}