BAEL-5140 Retrieve field's annotations (eugenp#11254)

core-java-modules/core-java-annotations/pom.xml

@@ -1,7 +1,7 @@
 <?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">
+         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>core-java-annotations</artifactId>
     <version>0.1.0-SNAPSHOT</version>
@@ -14,6 +14,19 @@
         <version>0.0.1-SNAPSHOT</version>
     </parent>
 
+    <dependencies>
+        <dependency>
+            <groupId>org.assertj</groupId>
+            <artifactId>assertj-core</artifactId>
+            <version>${assertj-core.version}</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <assertj-core.version>3.10.0</assertj-core.version>
+    </properties>
+
     <build>
         <finalName>core-java-annotations</finalName>
         <resources>

core-java-modules/core-java-annotations/src/main/java/com/baeldung/readannotations/ClassWithAnnotations.java

@@ -0,0 +1,9 @@
+package com.baeldung.readannotations;
+
+public class ClassWithAnnotations {
+
+    @FirstAnnotation
+    @SecondAnnotation
+    @ThirdAnnotation
+    private String classMember;
+}

core-java-modules/core-java-annotations/src/main/java/com/baeldung/readannotations/FirstAnnotation.java

@@ -0,0 +1,8 @@
+package com.baeldung.readannotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface FirstAnnotation {
+}

core-java-modules/core-java-annotations/src/main/java/com/baeldung/readannotations/SecondAnnotation.java

@@ -0,0 +1,8 @@
+package com.baeldung.readannotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.RUNTIME)
+public @interface SecondAnnotation {
+}

core-java-modules/core-java-annotations/src/main/java/com/baeldung/readannotations/ThirdAnnotation.java

@@ -0,0 +1,8 @@
+package com.baeldung.readannotations;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+@Retention(RetentionPolicy.SOURCE)
+public @interface ThirdAnnotation {
+}

core-java-modules/core-java-annotations/src/test/java/com/baeldung/readannotations/ClassWithAnnotationsUnitTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.readannotations;
+
+import org.junit.Test;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Field;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ClassWithAnnotationsUnitTest {
+
+    @Test
+    public void whenCallingGetDeclaredAnnotations_thenOnlyRuntimeAnnotationsAreAvailable() throws NoSuchFieldException {
+        Field classMemberField = ClassWithAnnotations.class.getDeclaredField("classMember");
+        Annotation[] annotations = classMemberField.getDeclaredAnnotations();
+        assertThat(annotations).hasSize(2);
+    }
+
+    @Test
+    public void whenCallingIsAnnotationPresent_thenOnlyRuntimeAnnotationsAreAvailable() throws NoSuchFieldException {
+        Field classMemberField = ClassWithAnnotations.class.getDeclaredField("classMember");
+        assertThat(classMemberField.isAnnotationPresent(FirstAnnotation.class)).isTrue();
+        assertThat(classMemberField.isAnnotationPresent(SecondAnnotation.class)).isTrue();
+        assertThat(classMemberField.isAnnotationPresent(ThirdAnnotation.class)).isFalse();
+    }
+
+    @Test
+    public void whenCallingGetDeclaredAnnotationsOrGetAnnotations_thenSameAnnotationsAreReturned() throws NoSuchFieldException {
+        Field classMemberField = ClassWithAnnotations.class.getDeclaredField("classMember");
+        Annotation[] declaredAnnotations = classMemberField.getDeclaredAnnotations();
+        Annotation[] annotations = classMemberField.getAnnotations();
+        assertThat(declaredAnnotations).containsExactly(annotations);
+    }
+}