Merge pull request #8924 from eardeleanu15/BAEL-3853-Helpful-NPE

BAEL-3853: Helpful NPE in Java 14

core-java-modules/core-java-14/src/main/java/com/baeldung/java14/helpfulnullpointerexceptions/HelpfulNullPointerException.java

@@ -0,0 +1,56 @@
+package com.baeldung.java14.helpfulnullpointerexceptions;
+
+public class HelpfulNullPointerException {
+
+    public static void main(String[] args) {
+        Employee employee = null;
+        employee.getName();
+    }
+
+    public String getEmployeeEmailAddress(Employee employee) {
+        String emailAddress = employee.getPersonalDetails().getEmailAddress().toLowerCase();
+        return emailAddress;
+    }
+
+    static class Employee {
+        String name;
+        PersonalDetails personalDetails;
+
+        public String getName() {
+            return name;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public PersonalDetails getPersonalDetails() {
+            return personalDetails;
+        }
+
+        public void setPersonalDetails(PersonalDetails personalDetails) {
+            this.personalDetails = personalDetails;
+        }
+    }
+
+    static class PersonalDetails {
+        String emailAddress;
+        String phone;
+
+        public String getEmailAddress() {
+            return emailAddress;
+        }
+
+        public void setEmailAddress(String emailAddress) {
+            this.emailAddress = emailAddress;
+        }
+
+        public String getPhone() {
+            return phone;
+        }
+
+        public void setPhone(String phone) {
+            this.phone = phone;
+        }
+    }
+}

core-java-modules/core-java-14/src/test/java/com/baeldung/java14/helpfulnullpointerexceptions/HelpfulNullPointerExceptionUnitTest.java

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+package com.baeldung.java14.helpfulnullpointerexceptions;
+
+import org.junit.Test;
+
+import static com.baeldung.java14.helpfulnullpointerexceptions.HelpfulNullPointerException.Employee;
+import static com.baeldung.java14.helpfulnullpointerexceptions.HelpfulNullPointerException.PersonalDetails;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class HelpfulNullPointerExceptionUnitTest {
+
+    @Test (expected = NullPointerException.class)
+    public void givenAnEmptyPersonalDetails_whenEmailAddressIsAccessed_thenThrowNPE() {
+        var helpfulNPE = new HelpfulNullPointerException();
+
+        var employee = new Employee();
+        employee.setName("Eduard");
+        employee.setPersonalDetails(new PersonalDetails());
+        helpfulNPE.getEmployeeEmailAddress(employee);
+    }
+
+    @Test
+    public void givenCompletePersonalDetails_whenEmailAddressIsAccessed_thenSuccess() {
+        var helpfulNPE = new HelpfulNullPointerException();
+        var emailAddress = "eduard@gmx.com";
+
+        var employee = new Employee();
+        employee.setName("Eduard");
+
+        var personalDetails = new PersonalDetails();
+        personalDetails.setEmailAddress(emailAddress.toUpperCase());
+        personalDetails.setPhone("1234");
+        employee.setPersonalDetails(personalDetails);
+
+        assertThat(helpfulNPE.getEmployeeEmailAddress(employee)).isEqualTo(emailAddress);
+    }
+
+}