Finding Annotations

Rewrite provides a shorthand for performing a search for annotations on classes, methods, and fields.

Let's start with an example annotation (the fact that this is a repeatable annotation is not a requirement in general):

package com.a;
import java.lang.annotation.Repeatable;

@Repeatable(Requests.class)
@interface Request {
	String value();
	String method() default "get";
}

Here is a class using the @Request annotation:

import com.a.*;
@Request("/api")                              // 1
public class A {

	@Request("/api")                          // 2
	@Request(value = "/api")                  // 3
	@Request(value = "/api", method = "get")  // 4
	public void apiEndpoint() {}
}

First, let's parse both classes and grab the Tr.CompilationUnit of class A.

Tr.CompilationUnit cu = parser.parse(Arrays.asList(a, request)).get(0);
Tr.ClassDecl clazz = cu.getFirstClass();

We can retrieve a list of the Tr.Annotation instances with (which matches all 4 annotations in our example, since it finds annotations both on class A and those defined inside of it:

clazz.findAnnotations("@com.a.Request");

We can search more specifically on the method:

clazz.methods().stream()
   .filter(m -> m.getSimpleName().equals("apiEndpoint"))
   .findAny()
   .map(m -> m.findAnnotations("@java.lang.Deprecated"))
   .orElse(Collections.emptyList());

To match annotations only with the value parameter (matches 1 and 2):

clazz.findAnnotations("@com.a.Request(\"/api\")");

To match annotations with named parameters (matches 4):

// order does not matter
clazz.findAnnotations("@com.a.Request(default=\"/api\", method=\"get\")");
clazz.findAnnotations("@com.a.Request(method=\"get\", default=\"/api\")");