Merge branch 'master' into bael-7169-update-readme

core-java-modules/core-java-lang-6/README.md

@@ -9,4 +9,5 @@ This module contains articles about core features in the Java language
 - [Get a Random Element From a Set in Java](https://www.baeldung.com/java-set-draw-sample)
 - [Stop Executing Further Code in Java](https://www.baeldung.com/java-stop-running-code)
 - [Using the Apache Commons Lang 3 for Comparing Objects in Java](https://www.baeldung.com/java-apache-commons-lang-3-compare-objects)
+- [Return First Non-null Value in Java](https://www.baeldung.com/java-first-non-null)
 - [Static Final Variables in Java](https://www.baeldung.com/java-static-final-variables)

core-java-modules/core-java-lang-6/src/main/java/com/baeldung/staticfinal/Bike.java

@@ -0,0 +1,14 @@
+package com.baeldung.staticfinal;
+
+import java.util.HashMap;
+
+public class Bike {
+    public static final int TIRE = 2;
+    public static final int PEDAL;
+    public static final HashMap<String, Integer> PART = new HashMap<>();
+
+    static {
+        PEDAL = 5;
+    }
+
+}

core-java-modules/core-java-lang-6/src/test/java/com/baeldung/staticfinal/BikeUnitTest.java

@@ -0,0 +1,33 @@
+package com.baeldung.staticfinal;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class BikeUnitTest {
+
+    @Test
+    void givenTireConstantSetUponDeclaration_whenGetTire_thenReturnTwo() {
+        assertEquals(2, Bike.TIRE);
+    }
+
+    @Test
+    void givenPedalConstantSetByStaticBlock_whenGetPedal_thenReturnFive() {
+        assertEquals(5, Bike.PEDAL);
+    }
+
+    @Test
+    void givenPartConstantObject_whenObjectStateChanged_thenCorrect() {
+        Bike.PART.put("seat", 1);
+        assertEquals(1, Bike.PART.get("seat"));
+
+        Bike.PART.put("seat", 5);
+        assertEquals(5, Bike.PART.get("seat"));
+    }
+
+    @Test
+    void givenMathClass_whenAccessingPiConstant_thenVerifyPiValueIsCorrect() {
+        assertEquals(3.141592653589793, Math.PI);
+    }
+
+}