From f6f63673a90aa7869bb1f10c17b923be11bb8c0c Mon Sep 17 00:00:00 2001
From: pedrolopes <pedroinf97@gmail.com>
Date: Thu, 12 Jan 2023 23:28:36 -0300
Subject: [PATCH] BAEL-5873: Check If All the Variables of a Class Are Null
 (#13285)

* model classes. unit tests. apache lang3 dependency.

* fix PR build
---
 .../core-java-lang-oop-others/pom.xml         |  8 ++++
 .../java/com/baeldung/nullchecking/Car.java   | 30 +++++++++++++
 .../baeldung/nullchecking/NullChecker.java    | 25 +++++++++++
 .../nullchecking/NullCheckUnitTest.java       | 45 +++++++++++++++++++
 4 files changed, 108 insertions(+)
 create mode 100644 core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/Car.java
 create mode 100644 core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/NullChecker.java
 create mode 100644 core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/nullchecking/NullCheckUnitTest.java

diff --git a/core-java-modules/core-java-lang-oop-others/pom.xml b/core-java-modules/core-java-lang-oop-others/pom.xml
index d9d147f34a..dea92067f2 100644
--- a/core-java-modules/core-java-lang-oop-others/pom.xml
+++ b/core-java-modules/core-java-lang-oop-others/pom.xml
@@ -13,4 +13,12 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-lang3</artifactId>
+            <version>3.12.0</version>
+        </dependency>
+    </dependencies>
+
 </project>
\ No newline at end of file
diff --git a/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/Car.java b/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/Car.java
new file mode 100644
index 0000000000..975006d8df
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/Car.java
@@ -0,0 +1,30 @@
+package com.baeldung.nullchecking;
+
+import java.util.Objects;
+import java.util.stream.Stream;
+
+public class Car {
+
+    Integer power;
+
+    Integer year;
+
+    public boolean allNull() {
+
+        if (power != null) {
+            return false;
+        }
+
+        if (year != null) {
+            return false;
+        }
+
+        return true;
+    }
+
+    public boolean allNullV2() {
+
+        return Stream.of(power, year)
+                .allMatch(Objects::isNull);
+    }
+}
diff --git a/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/NullChecker.java b/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/NullChecker.java
new file mode 100644
index 0000000000..5630577cdf
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-others/src/main/java/com/baeldung/nullchecking/NullChecker.java
@@ -0,0 +1,25 @@
+package com.baeldung.nullchecking;
+
+import java.lang.reflect.Field;
+import java.util.Arrays;
+import java.util.Objects;
+
+public class NullChecker {
+
+    public static boolean allNull(Object target) {
+
+        return Arrays.stream(target.getClass()
+                        .getDeclaredFields())
+                .peek(f -> f.setAccessible(true))
+                .map(f -> getFieldValue(f, target))
+                .allMatch(Objects::isNull);
+    }
+
+    private static Object getFieldValue(Field field, Object target) {
+        try {
+            return field.get(target);
+        } catch (IllegalAccessException e) {
+            throw new RuntimeException(e);
+        }
+    }
+}
diff --git a/core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/nullchecking/NullCheckUnitTest.java b/core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/nullchecking/NullCheckUnitTest.java
new file mode 100644
index 0000000000..db8aab8193
--- /dev/null
+++ b/core-java-modules/core-java-lang-oop-others/src/test/java/com/baeldung/nullchecking/NullCheckUnitTest.java
@@ -0,0 +1,45 @@
+package com.baeldung.nullchecking;
+
+import org.apache.commons.lang3.ObjectUtils;
+import org.junit.Test;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+public class NullCheckUnitTest {
+
+    @Test
+    public void givenNullFields_whenCheckForNullsUsingIfs_thenReturnCorrectValue(){
+        Car car = new Car();
+
+        boolean result = car.allNull();
+
+        assertTrue(result);
+    }
+
+    @Test
+    public void givenNullFields_whenCheckForNullsUsingStreams_thenReturnCorrectValue(){
+        Car car = new Car();
+
+        boolean result = car.allNullV2();
+
+        assertTrue(result);
+    }
+
+    @Test
+    public void givenNullFields_whenCheckForNullsUsingApacheCommons_thenReturnCorrectValue(){
+        Car car = new Car();
+
+        boolean result = ObjectUtils.allNull(car.power, car.year);
+
+        assertTrue(result);
+    }
+
+    @Test
+    public void givenNullFields_whenCheckForNullsUsingReflection_thenReturnCorrectValue(){
+        Car car = new Car();
+
+        boolean result = NullChecker.allNull(car);
+
+        assertTrue(result);
+    }
+}