Bael 3404 strictfp in java (#8157)

* BAEL-3404 Creating new OOP module

* BAEL-3404 Code changes

core-java-modules/core-java-lang-oop-4/src/main/java/com/baeldung/strictfpUsage/Circle.java

@@ -0,0 +1,5 @@
+package com.baeldung.strictfpUsage;
+
+public strictfp interface Circle {
+    double computeArea(double radius);
+}

core-java-modules/core-java-lang-oop-4/src/main/java/com/baeldung/strictfpUsage/ScientificCalculator.java

@@ -0,0 +1,12 @@
+package com.baeldung.strictfpUsage;
+
+public strictfp class ScientificCalculator {
+
+    public double sum(double value1, double value2) {
+        return value1 + value2;
+    }
+
+    public double diff(double value1, double value2) {
+        return value1 - value2;
+    }
+}

core-java-modules/core-java-lang-oop-4/src/test/java/com/baeldung/strictfpUsage/ScientificCalculatorUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.strictfpUsage;
+
+import org.junit.Test;
+
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+
+public class ScientificCalculatorUnitTest {
+
+    @Test
+    public void whenMethodOfstrictfpClassInvoked_thenIdenticalResultOnAllPlatforms() {
+        ScientificCalculator calculator = new ScientificCalculator();
+        double result = calculator.sum(23e10, 98e17);
+        assertThat(result, is(9.800000230000001E18));
+        result = calculator.diff(Double.MAX_VALUE, 1.56);
+        assertThat(result, is(1.7976931348623157E308));
+    }
+}