JSpecify Null Safety (#18684)

Author: karpado

static-analysis-modules/jspecify-nullsafety/pom.xml

@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <artifactId>jspecify-nullsafety</artifactId>
+    <packaging>jar</packaging>
+    <name>core-java-8-datetime-3</name>
+
+    <parent>
+        <groupId>com.baeldung</groupId>
+        <artifactId>static-analysis-modules</artifactId>
+        <version>1.0-SNAPSHOT</version>
+    </parent>
+
+    <dependencies>
+		<dependency>
+			<groupId>org.jspecify</groupId>
+			<artifactId>jspecify</artifactId>
+			<version>0.3.0</version>
+		</dependency>
+    </dependencies>
+
+</project>

static-analysis-modules/jspecify-nullsafety/src/test/java/com/baeldung/jspecify/JspecifyNullSafetyTest.java

@@ -0,0 +1,76 @@
+package com.baeldung.jspecify;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.util.Objects;
+import java.util.Optional;
+
+import org.jspecify.annotations.Nullable;
+import org.junit.jupiter.api.Test;
+
+public class JspecifyNullSafetyTest {
+
+    @Test
+    void givenKnownUserId_whenFindNickname_thenReturnsOptionalWithValue() {
+        Optional<String> nickname = findNickname("user123");
+
+        assertTrue(nickname.isPresent());
+        assertEquals("CoolUser", nickname.get());
+    }
+
+    @Test
+    void givenUnknownUserId_whenFindNickname_thenReturnsEmptyOptional() {
+        Optional<String> nickname = findNickname("unknownUser");
+
+        assertTrue(nickname.isEmpty());
+    }
+
+    @Test
+    void givenNonNullArgument_whenValidate_thenDoesNotThrowException() {
+        String result = processNickname("CoolUser");
+        assertEquals("Processed: CoolUser", result);
+    }
+
+    @Test
+    void givenNullArgument_whenValidate_thenThrowsNullPointerException() {
+        assertThrows(NullPointerException.class, () -> processNickname(null));
+    }
+
+    @Test
+    void givenUnknownUserId_whenFindNicknameOrNull_thenReturnsNull() {
+        String nickname = findNicknameOrNull("unknownUser");
+        assertTrue(nickname == null);
+    }
+
+    @Test
+    void givenNullableMethodResult_whenWrappedInOptional_thenHandledSafely() {
+        String nickname = findNicknameOrNull("unknownUser");
+        Optional<String> safeNickname = Optional.ofNullable(nickname);
+
+        assertTrue(safeNickname.isEmpty());
+    }
+
+    private Optional<String> findNickname(String userId) {
+        if ("user123".equals(userId)) {
+            return Optional.of("CoolUser");
+        } else {
+            return Optional.empty();
+        }
+    }
+
+    @Nullable
+    private String findNicknameOrNull(String userId) {
+        if ("user123".equals(userId)) {
+            return "CoolUser";
+        } else {
+            return null;
+        }
+    }
+
+    private String processNickname(String nickname) {
+        Objects.requireNonNull(nickname, "Nickname must not be null");
+        return "Processed: " + nickname;
+    }
+}

static-analysis-modules/pom.xml

@@ -17,6 +17,7 @@
     <modules>
         <!-- <module>error-prone-library</module> --> <!-- requires additional configuration to be compiled due to the JVM strong encapsulation -->
         <module>infer</module>
+		<module>jspecify-nullsafety</module>
     </modules>
 
     <properties>