5 - Fifth commit to split core-java. This one includes:

* to core-java-lang:
  * https://www.baeldung.com/java-separate-double-into-integer-decimal-parts
  * https://www.baeldung.com/java-sneaky-throws
  * https://www.baeldung.com/java-inheritance-composition
* to core-java-array:
  * https://www.baeldung.com/java-array-copy
  * https://www.baeldung.com/java-initialize-array
  * https://www.baeldung.com/java-array-contains-value
  * https://www.baeldung.com/java-invert-array
  * https://www.baeldung.com/java-array-sum-average
  * https://www.baeldung.com/java-jagged-arrays
  * https://www.baeldung.com/java-util-arrays
  * https://www.baeldung.com/java-common-array-operations (from core-java-collections)

core-java-lang/src/test/java/com/baeldung/inheritancecomposition/test/ActressUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Actress;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class ActressUnitTest {
+    
+    private static Actress actress;
+    
+    @BeforeClass
+    public static void setUpActressInstance() {
+        actress = new Actress("Susan", "susan@domain.com", 30);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetName_thenEqual() {
+        assertThat(actress.getName()).isEqualTo("Susan");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetEmail_thenEqual() {
+        assertThat(actress.getEmail()).isEqualTo("susan@domain.com");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledgetAge_thenEqual() {
+        assertThat(actress.getAge()).isEqualTo(30);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledreadScript_thenEqual() {
+        assertThat(actress.readScript("Psycho")).isEqualTo("Reading the script of Psycho");
+    }
+    
+    @Test
+    public void givenActressInstance_whenCalledperfomRole_thenEqual() {
+        assertThat(actress.performRole()).isEqualTo("Performing a role");
+    }
+}

core-java-lang/src/test/java/com/baeldung/inheritancecomposition/test/CompositionUnitTest.java

@@ -0,0 +1,24 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Computer;
+import com.baeldung.inheritancecomposition.model.Memory;
+import com.baeldung.inheritancecomposition.model.Processor;
+import com.baeldung.inheritancecomposition.model.StandardMemory;
+import com.baeldung.inheritancecomposition.model.StandardProcessor;
+import com.baeldung.inheritancecomposition.model.StandardSoundCard;
+import java.util.Optional;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class CompositionUnitTest {
+    
+    
+    @Test
+    public void givenComputerInstance_whenExtractedEachField_thenThreeAssertions() {
+        Computer computer = new Computer(new StandardProcessor("Intel I3"), new StandardMemory("Kingston", "1TB"));
+        computer.setSoundCard(new StandardSoundCard("Generic Sound Card"));
+        assertThat(computer.getProcessor()).isInstanceOf(Processor.class);
+        assertThat(computer.getMemory()).isInstanceOf(Memory.class);
+        assertThat(computer.getSoundCard()).isInstanceOf(Optional.class);
+    }
+}

core-java-lang/src/test/java/com/baeldung/inheritancecomposition/test/InheritanceUnitTest.java

@@ -0,0 +1,20 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Actress;
+import com.baeldung.inheritancecomposition.model.Person;
+import com.baeldung.inheritancecomposition.model.Waitress;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class InheritanceUnitTest {
+    
+    @Test
+    public void givenWaitressInstance_whenCheckedType_thenIsInstanceOfPerson() {
+        assertThat(new Waitress("Mary", "mary@domain.com", 22)).isInstanceOf(Person.class);
+    }
+    
+    @Test
+    public void givenActressInstance_whenCheckedType_thenIsInstanceOfPerson() {
+        assertThat(new Actress("Susan", "susan@domain.com", 30)).isInstanceOf(Person.class);
+    }
+}

core-java-lang/src/test/java/com/baeldung/inheritancecomposition/test/PersonUnitTest.java

@@ -0,0 +1,31 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Person;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class PersonUnitTest {
+    
+    private static Person person;
+    
+    @BeforeClass
+    public static void setPersonInstance() {
+        person = new Person("John", "john@domain.com", 35);
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetName_thenEqual() {
+        assertThat(person.getName()).isEqualTo("John");
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetEmail_thenEqual() {
+        assertThat(person.getEmail()).isEqualTo("john@domain.com");
+    }
+    
+    @Test
+    public void givenPersonInstance_whenCalledgetAge_thenEqual() {
+        assertThat(person.getAge()).isEqualTo(35);
+    }
+}

core-java-lang/src/test/java/com/baeldung/inheritancecomposition/test/WaitressUnitTest.java

@@ -0,0 +1,46 @@
+package com.baeldung.inheritancecomposition.test;
+
+import com.baeldung.inheritancecomposition.model.Waitress;
+import org.junit.BeforeClass;
+import org.junit.Test;
+import static org.assertj.core.api.Assertions.*;
+
+public class WaitressUnitTest {
+
+    private static Waitress waitress;
+
+    @BeforeClass
+    public static void setUpWaitressInstance() {
+        waitress = new Waitress("Mary", "mary@domain.com", 22);
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetName_thenOneAssertion() {
+        assertThat(waitress.getName()).isEqualTo("Mary");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetEmail_thenOneAssertion() {
+        assertThat(waitress.getEmail()).isEqualTo("mary@domain.com");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledgetAge_thenOneAssertion() {
+        assertThat(waitress.getAge()).isEqualTo(22);
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveStarter_thenOneAssertion() {
+        assertThat(waitress.serveStarter("mixed salad")).isEqualTo("Serving a mixed salad");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveMainCourse_thenOneAssertion() {
+        assertThat(waitress.serveMainCourse("steak")).isEqualTo("Serving a steak");
+    }
+
+    @Test
+    public void givenWaitressInstance_whenCalledserveDessert_thenOneAssertion() {
+        assertThat(waitress.serveDessert("cup of coffee")).isEqualTo("Serving a cup of coffee");
+    }
+}

core-java-lang/src/test/java/com/baeldung/sneakythrows/SneakyRunnableUnitTest.java

@@ -0,0 +1,17 @@
+package com.baeldung.sneakythrows;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class SneakyRunnableUnitTest {
+
+    @Test
+    public void whenCallSneakyRunnableMethod_thenThrowException() {
+        try {
+            new SneakyRunnable().run();
+        } catch (Exception e) {
+            assertEquals(InterruptedException.class, e.getStackTrace());
+        }
+    }
+}

core-java-lang/src/test/java/com/baeldung/sneakythrows/SneakyThrowsUnitTest.java

@@ -0,0 +1,18 @@
+package com.baeldung.sneakythrows;
+
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class SneakyThrowsUnitTest {
+
+    @Test
+    public void whenCallSneakyMethod_thenThrowSneakyException() {
+        try {
+            SneakyThrows.throwsSneakyIOException();
+        } catch (Exception ex) {
+            assertEquals("sneaky", ex.getMessage().toString());
+        }
+    }
+
+}