Initial Commit (#142)

* Initial Commit

Added Maven Annotation Processor Demo project. Initial commit.

* Test - checking

* Delete test.rtf

* Initial commits

Initial commits for sample code

* Update SuppressWarningsDemo.java

* Code changes till SafeVarargs

Code changes till SafeVarargs

* Completed source code

Completed source code

* Final draft

Final draft version. Grammarly check done.

* Deleted java docs

Deleted java docs

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/pom.xml

@@ -0,0 +1,42 @@
+<?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">
+    <parent>
+        <artifactId>AnnotationProcessorDemo</artifactId>
+        <groupId>com.reflectoring.annotation.processor</groupId>
+        <version>1.0</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.reflectoring.annotation.processor</groupId>
+    <artifactId>annotation-processor</artifactId>
+    <version>1.0</version>
+
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.google.auto.service</groupId>
+            <artifactId>auto-service</artifactId>
+            <version>1.0.1</version>
+            <scope>provided</scope>
+        </dependency>
+        <!-- https://mvnrepository.com/artifact/com.squareup/javapoet -->
+        <dependency>
+            <groupId>com.squareup</groupId>
+            <artifactId>javapoet</artifactId>
+            <version>1.9.0</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.commons</groupId>
+            <artifactId>commons-text</artifactId>
+            <version>1.9</version>
+        </dependency>
+
+    </dependencies>
+
+</project>

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/src/main/java/com/reflectoring/annotation/processor/Builder.java

@@ -0,0 +1,11 @@
+package com.reflectoring.annotation.processor;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target({ElementType.TYPE})
+@Retention(RetentionPolicy.SOURCE)
+public @interface Builder {
+}

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/src/main/java/com/reflectoring/annotation/processor/BuilderProcessor.java

@@ -0,0 +1,249 @@
+package com.reflectoring.annotation.processor;
+
+import com.google.auto.service.AutoService;
+import com.squareup.javapoet.*;
+import org.apache.commons.text.CaseUtils;
+
+import javax.annotation.processing.*;
+import javax.lang.model.SourceVersion;
+import javax.lang.model.element.Element;
+import javax.lang.model.element.ElementKind;
+import javax.lang.model.element.Modifier;
+import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.Elements;
+import javax.tools.Diagnostic;
+import javax.tools.JavaFileObject;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+@SupportedAnnotationTypes("com.reflectoring.annotation.processor.Builder")
+@SupportedSourceVersion(SourceVersion.RELEASE_11)
+@AutoService(Processor.class)
+public class BuilderProcessor extends AbstractProcessor {
+
+    private Filer filer;
+    private Messager messager;
+    private Elements elementUtils;
+
+    @Override
+    public synchronized void init(ProcessingEnvironment processingEnv) {
+
+        super.init(processingEnv);
+        filer = processingEnv.getFiler();
+        messager = processingEnv.getMessager();
+        elementUtils = processingEnv.getElementUtils();
+    }
+
+    @Override
+    public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment roundEnv) {
+
+        for (Element typeElement : roundEnv.getElementsAnnotatedWith(Builder.class)) {
+
+            List<Element> fieldElements = typeElement.getEnclosedElements().stream().filter(e -> ElementKind.FIELD.equals(e.getKind())).collect(
+                    Collectors.toList());
+
+            String packageName = elementUtils.getPackageOf(typeElement).getQualifiedName().toString();
+            String className = typeElement.getSimpleName().toString();
+            String builderName = String.format("%sBuilder", typeElement.getSimpleName().toString());
+            String classVariableName = CaseUtils.toCamelCase(typeElement.getSimpleName().toString(), false, '_');
+
+            try {
+                //writeBuilderClass(packageName, className, classVariableName, builderName, fieldElements);
+
+                writeJavaPoetBuilderClass(packageName, className, classVariableName, builderName, fieldElements, typeElement);
+            } catch (IOException e) {
+                messager.printMessage(Diagnostic.Kind.ERROR, "Failed to write file for element", typeElement);
+            }
+        }
+
+        return true;
+    }
+
+    private String getBaseName(String name) {
+
+        int lastPeriodIndex = name.lastIndexOf('.');
+        if (lastPeriodIndex > 0) {
+            name = name.substring(lastPeriodIndex + 1);
+        }
+
+        return name;
+    }
+
+    private void writeBuilderClass(String packageName, String className, String classVariableName, String builderName,
+                                   List<Element> fieldElements) throws IOException {
+
+        JavaFileObject builder = processingEnv.getFiler().createSourceFile(builderName);
+
+        try (PrintWriter out = new PrintWriter(builder.openWriter())) {
+
+            // Write the Package name
+            out.print("package ");
+            out.print(packageName);
+            out.println(";");
+            out.println();
+
+            // Write the Class name
+            out.print("public final class ");
+            out.print(builderName);
+            out.println(" {");
+            out.println();
+
+            // Write the Field names
+            for (Element fieldElement : fieldElements) {
+
+                TypeMirror typeMirror = fieldElement.asType();
+
+                String fieldTypeName = getBaseName(typeMirror.toString());
+                String fieldName = getBaseName(fieldElement.getSimpleName().toString());
+
+                out.print("private ");
+                out.print(fieldTypeName);
+                out.print(" ");
+                out.print(fieldName);
+                out.print(";");
+                out.println();
+            }
+
+            out.println();
+
+            // Write the Setters
+            for (Element fieldElement : fieldElements) {
+
+                TypeMirror typeMirror = fieldElement.asType();
+
+                String fieldTypeName = getBaseName(typeMirror.toString());
+                String fieldName = getBaseName(fieldElement.getSimpleName().toString());
+
+                out.print("public ");
+                out.print(" ");
+                out.print(builderName);
+                out.print(" ");
+                out.print(fieldName);
+                out.print("(");
+                out.print(fieldTypeName);
+                out.print(" ");
+                out.print(fieldName);
+                out.print(") {");
+                out.println();
+                out.print("     this.");
+                out.print(fieldName);
+                out.print(" = ");
+                out.print(fieldName);
+                out.print(";");
+                out.println();
+                out.print("     return this;");
+                out.println();
+                out.print("}");
+                out.println();
+                out.println();
+            }
+
+            // Write the build function
+            out.print("public ");
+            out.print(" ");
+            out.print(className);
+            out.print(" build() {");
+            out.println();
+            out.print("     ");
+            out.print(className);
+            out.print(" ");
+            out.print(classVariableName);
+            out.print(" = new ");
+            out.print(className);
+            out.print("();");
+            out.println();
+
+            for (Element fieldElement : fieldElements) {
+
+                TypeMirror typeMirror = fieldElement.asType();
+
+                String fieldTypeName = getBaseName(typeMirror.toString());
+                String fieldName = getBaseName(fieldElement.getSimpleName().toString());
+
+                out.print("     ");
+                out.print(classVariableName);
+                out.print(".set");
+                out.print(CaseUtils.toCamelCase(fieldName, true, '_'));
+                out.print("(this.");
+                out.print(fieldName);
+                out.println(");");
+            }
+
+            out.println();
+            out.print("     return ");
+            out.print(classVariableName);
+            out.print(";");
+            out.println();
+            out.println("   }");
+            out.println("}");
+        }
+    }
+
+    private void writeJavaPoetBuilderClass(String packageName, String className, String classVariableName, String builderName,
+                                   List<Element> fieldElements, Element typeElement) throws IOException {
+
+        ClassName builderType = ClassName.get(packageName, builderName);
+
+        List<FieldSpec> fields = new ArrayList<>(fieldElements.size());
+        List<MethodSpec> fieldSetters = new ArrayList<>(fieldElements.size());
+
+        // Generate the fields and field setters
+        generateFieldsAndSetters(fields, fieldSetters, fieldElements, builderType);
+
+        TypeName targetType = TypeName.get(typeElement.asType());
+
+        // Generate the build method
+        MethodSpec buildMethod = generateBuildMethod(targetType, classVariableName, fields);
+
+        TypeSpec builder = TypeSpec.classBuilder(builderType)
+                .addModifiers(Modifier.PUBLIC, Modifier.FINAL)
+                .addFields(fields)
+                .addMethods(fieldSetters)
+                .addMethod(buildMethod).build();
+
+        JavaFile file = JavaFile.builder(builderType.packageName(), builder.toBuilder().build()).build();
+
+        file.writeTo(filer);
+    }
+
+    private void generateFieldsAndSetters(List<FieldSpec> fields, List<MethodSpec> fieldSetters, List<Element> fieldElements, ClassName builderType){
+
+        for (Element fieldElement : fieldElements) {
+
+            TypeName typeName = TypeName.get(fieldElement.asType());
+            String fieldName = getBaseName(fieldElement.getSimpleName().toString());
+
+            fields.add(FieldSpec.builder(typeName, fieldName, Modifier.PRIVATE).build());
+
+            fieldSetters.add(
+                    MethodSpec.methodBuilder(fieldName)
+                            .addModifiers(Modifier.PUBLIC)
+                            .returns(builderType)
+                            .addParameter(typeName, fieldName)
+                            .addStatement("this.$N = $N", fieldName, fieldName)
+                            .addStatement("return this").build());
+        }
+    }
+
+    private MethodSpec generateBuildMethod(TypeName targetType, String variableName, List<FieldSpec> fields) {
+
+        MethodSpec.Builder buildMethodBuilder = MethodSpec.methodBuilder("build")
+                .addModifiers(Modifier.PUBLIC)
+                .returns(targetType)
+                .addStatement("$1T $2N = new $1T()", targetType, variableName);
+
+        for (FieldSpec field : fields) {
+
+            buildMethodBuilder.addStatement("$1N.set$2N(this.$3N)", variableName, CaseUtils.toCamelCase(field.name, true, '_'), field.name);
+        }
+
+        buildMethodBuilder.addStatement("return $N", variableName);
+
+        return buildMethodBuilder.build();
+    }
+}

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/target/classes/META-INF/services/javax.annotation.processing.Processor

@@ -0,0 +1 @@
+com.reflectoring.annotation.processor.BuilderProcessor

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/target/maven-archiver/pom.properties

@@ -0,0 +1,5 @@
+#Generated by Maven
+#Wed Jan 26 14:56:24 EST 2022
+groupId=com.reflectoring.annotation.processor
+artifactId=annotation-processor
+version=1.0

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/target/maven-status/maven-compiler-plugin/compile/default-compile/createdFiles.lst

@@ -0,0 +1,3 @@
+META-INF\services\javax.annotation.processing.Processor
+com\reflectoring\annotation\processor\Builder.class
+com\reflectoring\annotation\processor\BuilderProcessor.class

core-java/annotation-processing/AnnotationProcessorDemo/annotation-processor/target/maven-status/maven-compiler-plugin/compile/default-compile/inputFiles.lst

@@ -0,0 +1,2 @@
+D:\Documents\IntelliJ Projects\AnnotationProcessorDemo\annotation-processor\src\main\java\com\reflectoring\annotation\processor\Builder.java
+D:\Documents\IntelliJ Projects\AnnotationProcessorDemo\annotation-processor\src\main\java\com\reflectoring\annotation\processor\BuilderProcessor.java

core-java/annotation-processing/AnnotationProcessorDemo/core/pom.xml

@@ -0,0 +1,28 @@
+<?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">
+    <parent>
+        <artifactId>AnnotationProcessorDemo</artifactId>
+        <groupId>com.reflectoring.annotation.processor</groupId>
+        <version>1.0</version>
+    </parent>
+
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.reflectoring.annotation.processor</groupId>
+    <version>1.0</version>
+    <artifactId>core</artifactId>
+
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.reflectoring.annotation.processor</groupId>
+            <artifactId>annotation-processor</artifactId>
+            <version>1.0</version>
+        </dependency>
+    </dependencies>
+</project>

core-java/annotation-processing/AnnotationProcessorDemo/core/src/main/java/com/reflectoring/annotation/processor/Department.java

@@ -0,0 +1,23 @@
+package com.reflectoring.annotation.processor;
+
+public class Department {
+
+    private int id;
+    private String name;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/src/main/java/com/reflectoring/annotation/processor/Employee.java

@@ -0,0 +1,23 @@
+package com.reflectoring.annotation.processor;
+
+public class Employee {
+
+    private int id;
+    private String department;
+
+    public int getId() {
+        return id;
+    }
+
+    public void setId(int id) {
+        this.id = id;
+    }
+
+    public String getDepartment() {
+        return department;
+    }
+
+    public void setDepartment(String department) {
+        this.department = department;
+    }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/src/test/java/com/test/BuilderTest.java

@@ -0,0 +1,15 @@
+package com.test;
+
+import com.reflectoring.annotation.processor.Employee;
+
+public class BuilderTest {
+
+    public static void main(String[] args) {
+
+        Employee employee = new EmployeeBuilder()
+                            .department("Sales")
+                            .build();
+
+        System.out.println("Employee dept: " + employee.getDepartment());
+    }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/src/test/java/com/test/DepartmentBuilder.java

@@ -0,0 +1,27 @@
+package com.test;
+
+import com.reflectoring.annotation.processor.Department;
+
+public final class DepartmentBuilder {
+
+private int id;
+private String name;
+
+public  DepartmentBuilder id(int id) {
+     this.id = id;
+     return this;
+}
+
+public  DepartmentBuilder name(String name) {
+     this.name = name;
+     return this;
+}
+
+public Department build() {
+     Department department = new Department();
+     department.setId(this.id);
+     department.setName(this.name);
+
+     return department;
+   }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/src/test/java/com/test/EmployeeBuilder.java

@@ -0,0 +1,27 @@
+package com.test;
+
+import com.reflectoring.annotation.processor.Employee;
+
+public final class EmployeeBuilder {
+
+private int id;
+private String department;
+
+public  EmployeeBuilder id(int id) {
+     this.id = id;
+     return this;
+}
+
+public  EmployeeBuilder department(String department) {
+     this.department = department;
+     return this;
+}
+
+public Employee build() {
+     Employee employee = new Employee();
+     employee.setId(this.id);
+     employee.setDepartment(this.department);
+
+     return employee;
+   }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/target/generated-sources/annotations/com/reflectoring/annotation/processor/DepartmentBuilder.java

@@ -0,0 +1,26 @@
+package com.reflectoring.annotation.processor;
+
+import java.lang.String;
+
+public final class DepartmentBuilder {
+  private int id;
+
+  private String name;
+
+  public DepartmentBuilder id(int id) {
+    this.id = id;
+    return this;
+  }
+
+  public DepartmentBuilder name(String name) {
+    this.name = name;
+    return this;
+  }
+
+  public Department build() {
+    Department department = new Department();
+    department.setId(this.id);
+    department.setName(this.name);
+    return department;
+  }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/target/generated-sources/annotations/com/reflectoring/annotation/processor/EmployeeBuilder.java

@@ -0,0 +1,26 @@
+package com.reflectoring.annotation.processor;
+
+import java.lang.String;
+
+public final class EmployeeBuilder {
+  private int id;
+
+  private String department;
+
+  public EmployeeBuilder id(int id) {
+    this.id = id;
+    return this;
+  }
+
+  public EmployeeBuilder department(String department) {
+    this.department = department;
+    return this;
+  }
+
+  public Employee build() {
+    Employee employee = new Employee();
+    employee.setId(this.id);
+    employee.setDepartment(this.department);
+    return employee;
+  }
+}

core-java/annotation-processing/AnnotationProcessorDemo/core/target/maven-status/maven-compiler-plugin/compile/default-compile/createdFiles.lst

@@ -0,0 +1,4 @@
+com\reflectoring\annotation\processor\Employee.class
+com\reflectoring\annotation\processor\Department.class
+com\reflectoring\annotation\processor\EmployeeBuilder.class
+com\reflectoring\annotation\processor\DepartmentBuilder.class

core-java/annotation-processing/AnnotationProcessorDemo/core/target/maven-status/maven-compiler-plugin/compile/default-compile/inputFiles.lst

@@ -0,0 +1,2 @@
+D:\Documents\IntelliJ Projects\AnnotationProcessorDemo\core\src\main\java\com\reflectoring\annotation\processor\Employee.java
+D:\Documents\IntelliJ Projects\AnnotationProcessorDemo\core\src\main\java\com\reflectoring\annotation\processor\Department.java

core-java/annotation-processing/AnnotationProcessorDemo/pom.xml

@@ -0,0 +1,21 @@
+<?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>
+
+    <groupId>com.reflectoring.annotation.processor</groupId>
+    <artifactId>AnnotationProcessorDemo</artifactId>
+    <packaging>pom</packaging>
+    <version>1.0</version>
+    <modules>
+        <module>core</module>
+        <module>annotation-processor</module>
+    </modules>
+
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+</project>

core-java/annotation-processing/introduction-to-annotations/annotations-demo/pom.xml

@@ -0,0 +1,16 @@
+<?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>
+
+    <groupId>org.example</groupId>
+    <artifactId>annotations-demo</artifactId>
+    <version>1.0-SNAPSHOT</version>
+
+    <properties>
+        <maven.compiler.source>11</maven.compiler.source>
+        <maven.compiler.target>11</maven.compiler.target>
+    </properties>
+
+</project>

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/AnnotatedMethods.java

@@ -0,0 +1,15 @@
+package com.reflectoring;
+
+public class AnnotatedMethods {
+
+    @Test
+    public void Test_1() {
+
+        System.out.println("This is the first test");
+    }
+
+    public void Test_2() {
+
+        System.out.println("This is the second test");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/BasicAnnotationTest.java

@@ -0,0 +1,8 @@
+package com.reflectoring;
+
+public class BasicAnnotationTest {
+
+    public static void main(String[] args) {
+
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/ClassRetention.java

@@ -0,0 +1,11 @@
+package com.reflectoring;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.CLASS)
+public @interface ClassRetention {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/Company.java

@@ -0,0 +1,12 @@
+package com.reflectoring;
+
+import java.lang.annotation.*;
+
+@Inherited
+@Documented
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface Company{
+    String name() default "ABC";
+    String city() default "XYZ";
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/CustomAnnotatedEmployee.java

@@ -0,0 +1,19 @@
+package com.reflectoring;
+
+@Company
+public class CustomAnnotatedEmployee {
+
+    private int id;
+    private String name;
+
+    public CustomAnnotatedEmployee(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public void getEmployeeDetails(){
+
+        System.out.println("Employee Id: " + id);
+        System.out.println("Employee Name: " + name);
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/CustomAnnotatedManager.java

@@ -0,0 +1,8 @@
+package com.reflectoring;
+
+public class CustomAnnotatedManager extends CustomAnnotatedEmployee{
+
+    public CustomAnnotatedManager(int id, String name) {
+        super(id, name);
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/DeprecatedDemo.java

@@ -0,0 +1,10 @@
+package com.reflectoring;
+
+public class DeprecatedDemo {
+
+    @Deprecated(since = "4.5", forRemoval = true)
+    public void testLegacyFunction() {
+
+        System.out.println("This is a legacy function");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/DeprecatedDemoTest.java

@@ -0,0 +1,10 @@
+package com.reflectoring;
+
+public class DeprecatedDemoTest {
+
+    public static void main(String[] args) {
+
+        DeprecatedDemo demo = new DeprecatedDemo();
+        demo.testLegacyFunction();
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/Employee.java

@@ -0,0 +1,10 @@
+package com.reflectoring;
+
+@Company
+public class Employee {
+
+    public void getEmployeeStatus(){
+
+        System.out.println("This is the Base Employee class");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/EmployeeRetentionAnnotation.java

@@ -0,0 +1,7 @@
+package com.reflectoring;
+
+@SourceRetention
+@RuntimeRetention
+@ClassRetention
+public class EmployeeRetentionAnnotation {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/FunctionalInterfaceTest.java

@@ -0,0 +1,15 @@
+package com.reflectoring;
+
+@FunctionalInterface
+interface Print {
+    void printString(String testString);
+}
+
+public class FunctionalInterfaceTest {
+
+    public static void main(String args[]) {
+
+        Print testPrint = (String testString) -> System.out.println(testString);
+        testPrint.printString("This is a String");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/Manager.java

@@ -0,0 +1,10 @@
+package com.reflectoring;
+
+public class Manager extends Employee {
+
+    @Override
+    public void getEmployeeStatus(){
+
+        System.out.println("This is the Manager class");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/MultiValueAnnotatedEmployee.java

@@ -0,0 +1,6 @@
+package com.reflectoring;
+
+@Company(name = "AAA", city = "ZZZ")
+public class MultiValueAnnotatedEmployee {
+
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/OverrideTest.java

@@ -0,0 +1,10 @@
+package com.reflectoring;
+
+public class OverrideTest {
+
+    public static void main(String[] args) {
+
+        Manager manager = new Manager();
+        manager.getEmployeeStatus();
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/RepeatableCompanies.java

@@ -0,0 +1,9 @@
+package com.reflectoring;
+
+import java.lang.annotation.*;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RepeatableCompanies {
+    RepeatableCompany[] value() default{};
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/RepeatableCompany.java

@@ -0,0 +1,11 @@
+package com.reflectoring;
+
+import java.lang.annotation.*;
+
+@Target(ElementType.TYPE)
+@Repeatable(RepeatableCompanies.class)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RepeatableCompany {
+    String name() default "Name_1";
+    String city() default "City_1";
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/RepeatedAnnotatedEmployee.java

@@ -0,0 +1,6 @@
+package com.reflectoring;
+
+@RepeatableCompany
+@RepeatableCompany(name =  "Name_2", city = "City_2")
+public class RepeatedAnnotatedEmployee {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/RetentionTest.java

@@ -0,0 +1,16 @@
+package com.reflectoring;
+
+public class RetentionTest {
+
+    public static void main(String[] args) {
+
+        SourceRetention[] sourceRetention = new EmployeeRetentionAnnotation().getClass().getAnnotationsByType(SourceRetention.class);
+        System.out.println("Source Retentions at run-time: " + sourceRetention.length);
+
+        RuntimeRetention[] runtimeRetention = new EmployeeRetentionAnnotation().getClass().getAnnotationsByType(RuntimeRetention.class);
+        System.out.println("Run-time Retentions at run-time: " + runtimeRetention.length);
+
+        ClassRetention[] classRetention = new EmployeeRetentionAnnotation().getClass().getAnnotationsByType(ClassRetention.class);
+        System.out.println("Class Retentions at run-time: " + classRetention.length);
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/RuntimeRetention.java

@@ -0,0 +1,11 @@
+package com.reflectoring;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface RuntimeRetention {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/SafeVarargsTest.java

@@ -0,0 +1,57 @@
+package com.reflectoring;
+
+import java.util.Arrays;
+import java.util.List;
+
+public class SafeVarargsTest {
+
+    private void printString(String test1) {
+
+        System.out.println(test1);
+    }
+
+    private void printString(String test1, String test2) {
+
+        System.out.println(test1);
+        System.out.println(test2);
+    }
+
+    private void printStringVarargs(String... tests) {
+
+        for (String test : tests) {
+
+            System.out.println(test);
+        }
+    }
+
+    @SafeVarargs
+    private void printStringSafeVarargs(List<String>... testStringLists) {
+
+        for (List<String> testStringList : testStringLists) {
+
+            for (String testString : testStringList) {
+
+                System.out.println(testString);
+            }
+        }
+    }
+
+    public static void main(String[] args) {
+
+        SafeVarargsTest test = new SafeVarargsTest();
+
+        test.printString("String1");
+        test.printString("*******");
+
+        test.printString("String1", "String2");
+        test.printString("*******");
+
+        test.printStringVarargs("String1", "String2");
+        test.printString("*******");
+
+        List<String> testStringList1 = Arrays.asList("One", "Two");
+        List<String> testStringList2 = Arrays.asList("Three", "Four");
+
+        test.printStringSafeVarargs(testStringList1, testStringList2);
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/SingleValueAnnotatedEmployee.java

@@ -0,0 +1,19 @@
+package com.reflectoring;
+
+@SingleValueAnnotationCompany("XYZ")
+public class SingleValueAnnotatedEmployee {
+
+    private int id;
+    private String name;
+
+    public SingleValueAnnotatedEmployee(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    public void getEmployeeDetails(){
+
+        System.out.println("Employee Id: " + id);
+        System.out.println("Employee Name: " + name);
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/SingleValueAnnotationCompany.java

@@ -0,0 +1,9 @@
+package com.reflectoring;
+
+import java.lang.annotation.*;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.RUNTIME)
+public @interface SingleValueAnnotationCompany {
+    String value() default "ABC";
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/SourceRetention.java

@@ -0,0 +1,8 @@
+package com.reflectoring;
+
+import java.lang.annotation.*;
+
+@Target(ElementType.TYPE)
+@Retention(RetentionPolicy.SOURCE)
+public @interface SourceRetention {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/SuppressWarningsDemo.java

@@ -0,0 +1,22 @@
+package com.reflectoring;
+
+import java.util.HashMap;
+import java.util.Map;
+
+@SuppressWarnings({"rawtypes", "unchecked"})
+public class SuppressWarningsDemo {
+
+    public static void main(String[] args) {
+
+        SuppressWarningsDemo swDemo = new SuppressWarningsDemo();
+        swDemo.testSuppressWarning();
+    }
+
+    public void testSuppressWarning() {
+
+        Map testMap = new HashMap();
+        testMap.put(1, "Item_1");
+        testMap.put(2, "Item_2");
+        testMap.put(3, "Item_3");
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/Test.java

@@ -0,0 +1,11 @@
+package com.reflectoring;
+
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.METHOD)
+public @interface Test {
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestAnnotatedMethods.java

@@ -0,0 +1,31 @@
+package com.reflectoring;
+
+import java.lang.annotation.Annotation;
+import java.lang.reflect.Method;
+
+public class TestAnnotatedMethods {
+
+    public static void main(String[] args) throws Exception {
+
+        Class<AnnotatedMethods> annotatedMethodsClass = AnnotatedMethods.class;
+
+        for (Method method : annotatedMethodsClass.getDeclaredMethods()) {
+
+            Annotation annotation = method.getAnnotation(Test.class);
+            Test test = (Test) annotation;
+
+            // If the annotation is not null
+            if (test != null) {
+
+                try {
+                    method.invoke(annotatedMethodsClass.getDeclaredConstructor().newInstance());
+                } catch (Throwable ex) {
+                    System.out.println(ex.getCause());
+                }
+
+            }
+        }
+    }
+}
+
+

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestCustomAnnotatedEmployee.java

@@ -0,0 +1,18 @@
+package com.reflectoring;
+
+import java.lang.annotation.Annotation;
+
+public class TestCustomAnnotatedEmployee {
+
+    public static void main(String[] args) {
+
+        CustomAnnotatedEmployee employee = new CustomAnnotatedEmployee(1, "John Doe");
+        employee.getEmployeeDetails();
+
+        Annotation companyAnnotation = employee.getClass().getAnnotation(Company.class);
+        Company company = (Company)companyAnnotation;
+
+        System.out.println("Company Name: " + company.name());
+        System.out.println("Company City: " + company.city());
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestCustomAnnotatedManager.java

@@ -0,0 +1,18 @@
+package com.reflectoring;
+
+import java.lang.annotation.Annotation;
+
+public class TestCustomAnnotatedManager {
+
+    public static void main(String[] args) {
+
+        CustomAnnotatedManager manager = new CustomAnnotatedManager(1, "John Doe");
+        manager.getEmployeeDetails();
+
+        Annotation companyAnnotation = manager.getClass().getAnnotation(Company.class);
+        Company company = (Company)companyAnnotation;
+
+        System.out.println("Company Name: " + company.name());
+        System.out.println("Company City: " + company.city());
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestMultiValueAnnotatedEmployee.java

@@ -0,0 +1,17 @@
+package com.reflectoring;
+
+import java.lang.annotation.Annotation;
+
+public class TestMultiValueAnnotatedEmployee {
+
+    public static void main(String[] args) {
+
+        MultiValueAnnotatedEmployee employee = new MultiValueAnnotatedEmployee();
+
+        Annotation companyAnnotation = employee.getClass().getAnnotation(Company.class);
+        Company company = (Company)companyAnnotation;
+
+        System.out.println("Company Name: " + company.name());
+        System.out.println("Company City: " + company.city());
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestRepeatedAnnotation.java

@@ -0,0 +1,14 @@
+package com.reflectoring;
+
+public class TestRepeatedAnnotation {
+
+    public static void main(String[] args) {
+
+        RepeatableCompany[] repeatableCompanies = RepeatedAnnotatedEmployee.class.getAnnotationsByType(RepeatableCompany.class);
+        for (RepeatableCompany repeatableCompany : repeatableCompanies) {
+
+            System.out.println("Name: " + repeatableCompany.name());
+            System.out.println("City: " + repeatableCompany.city());
+        }
+    }
+}

core-java/annotation-processing/introduction-to-annotations/annotations-demo/src/main/java/com/reflectoring/TestSingleValueAnnotatedEmployee.java

@@ -0,0 +1,17 @@
+package com.reflectoring;
+
+import java.lang.annotation.Annotation;
+
+public class TestSingleValueAnnotatedEmployee {
+
+    public static void main(String[] args) {
+
+        SingleValueAnnotatedEmployee employee = new SingleValueAnnotatedEmployee(1, "John Doe");
+        employee.getEmployeeDetails();
+
+        Annotation companyAnnotation = employee.getClass().getAnnotation(SingleValueAnnotationCompany.class);
+        SingleValueAnnotationCompany company = (SingleValueAnnotationCompany)companyAnnotation;
+
+        System.out.println("Company Name: " + company.value());
+    }
+}