An Annotation Processor to Process Version Annotations

.gitignore

@@ -0,0 +1,6 @@
+# Created by .ignore support plugin (hsz.mobi)
+.gitignore
+.idea/workspace.xml
+out/
+src/main/resources/
+target/

src/main/java/chapter1/annotation/VersionProcessor.java

@@ -0,0 +1,55 @@
+package chapter1.annotation;
+
+import javax.annotation.processing.AbstractProcessor;
+import javax.annotation.processing.Messager;
+import javax.annotation.processing.RoundEnvironment;
+import javax.lang.model.element.*;
+import javax.tools.Diagnostic;
+import java.util.Set;
+
+/**
+ * Project: BeginningJava8LanguageFeatures
+ * FileName: VersionProcessor
+ * Date: 2017-03-14
+ * Time: 오전 9:21
+ * Author: Hadeslee
+ * Note:
+ * To change this template use File | Settings | File Templates.
+ */
+public class VersionProcessor extends AbstractProcessor {
+    public VersionProcessor() {
+
+    }
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+        // Process all annotations
+        for (TypeElement currentAnnotation : annotations) {
+            javax.lang.model.element.Name qualifiedName = currentAnnotation.getQualifiedName();
+// check if it is a Version annotation
+            if (qualifiedName.contentEquals("chapter1.annotation.Version")) {
+// Look at all elements that have Version annotations
+                Set<? extends Element> annotatedElements;
+                annotatedElements = roundEnv.getElementsAnnotatedWith(
+                        currentAnnotation);
+                for (Element element : annotatedElements) {
+                    Version v = element.getAnnotation(Version.class);
+                    int major = v.major();
+                    int minor = v.minor();
+                    if (major < 0 || minor < 0) {
+// Print the error message
+                        String errorMsg = "Version cannot" +
+                                " be negative." +
+                                " major=" + major +
+                                " minor=" + minor;
+                        Messager messager =
+                                this.processingEnv.getMessager();
+                        messager.printMessage(Diagnostic.Kind.ERROR,
+                                errorMsg, element);
+                    }
+                }
+            }
+        }
+        return true;
+    }
+}