Java的注释

<code class="java">@annotationname
public class myclass{...}</code>

<code class="java">class Parent {
    void display(){
        System.out.println("hello from parent class");   
    }
}

class Child extends Parent{
    @Override
    void display(){
        System.out.println("hello from child class");
    }
}</code>

<code class="java">class Sum {
    @Deprecated
    int calcSum(int a, int b){
        return a+b; 
    }
}</code>

<code class="java">@SuppressWarnings("deprecation")
public class Main {
    public static void main(String[] args) {
        Sum sum = new Sum();
        int sumValue = sum.calcSum(1,2);
        System.out.println("sum is=" + sumValue);
    }
}</code>

<code class="java">@interface MyAnnotation {
  int num();
}

// 应用
@MyAnnotation(num=1)</code>

<code class="java">@interface MyAnnotation {
  int num1();
  int num2();
}

// 应用
@MyAnnotation(num1=1, num2=2)</code>

<code class="java">@Retention(RetentionPolicy.RUNTIME)  // 可在运行时访问
@Target(ElementType.METHOD)          // 只能应用于方法
@interface Review {
    String reviewerName() default "unknown";
}</code>

<code class="java">public class CodeReview {
    @Review(reviewerName = "John")
    public void reviewMethod1() {
        System.out.println("I need review");
    }
    @Review(reviewerName = "Mike")
    public void reviewMethod2() {
        System.out.println("I also need review");
    }
}</code>

<code class="java">public class MainExample {
    public static void main(String[] args) {
        Class<CodeReview> obj = CodeReview.class;
        for(Method method : obj.getDeclaredMethods()){
            if(method.isAnnotationPresent(Review.class)){
                Review annotation = method.getAnnotation(Review.class);
                System.out.println("Method: " + method.getName() + "| Reviewer: " + annotation.reviewerName());
            }
        }
    }
}</code>

<code>Method: reviewMethod1 | Reviewer: John
Method: reviewMethod2 | Reviewer: Mike</code>