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

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);
+    }
+}