[Java] New Java actor API (#7414)

java/tutorial/src/main/java/org/ray/exercise/Exercise01.java

@@ -3,7 +3,6 @@ package org.ray.exercise;
 import java.io.Serializable;
 import org.ray.api.Ray;
 import org.ray.api.RayObject;
-import org.ray.api.annotation.RayRemote;
 
 /**
  * Define a remote function, and execute multiple remote functions in parallel.
@@ -13,15 +12,12 @@ public class Exercise01 implements Serializable {
   /**
    * A plain remote function.
    */
-  // `@RayRemote` annotation converts a normal function to a remote function.
-  @RayRemote
   public static String sayHello() {
     String ret = "hello";
     System.out.println(ret);
     return ret;
   }
 
-  @RayRemote
   public static String sayWorld() {
     String ret = "world!";
     System.out.println(ret);

java/tutorial/src/main/java/org/ray/exercise/Exercise02.java

@@ -2,21 +2,18 @@ package org.ray.exercise;
 
 import org.ray.api.Ray;
 import org.ray.api.RayObject;
-import org.ray.api.annotation.RayRemote;
 
 /**
  * Execute remote functions in parallel with some dependencies.
  */
 public class Exercise02 {
 
-  @RayRemote
   public static String sayHello() {
     String ret = "hello";
     System.out.println(ret);
     return ret;
   }
 
-  @RayRemote
   public static String sayWorld() {
     String ret = "world!";
     System.out.println(ret);
@@ -26,7 +23,6 @@ public class Exercise02 {
   /**
    * A remote function with dependency.
    */
-  @RayRemote
   public static String merge(String hello, String world) {
     return hello + "," + world;
   }

java/tutorial/src/main/java/org/ray/exercise/Exercise03.java

@@ -2,7 +2,6 @@ package org.ray.exercise;
 
 import org.ray.api.Ray;
 import org.ray.api.RayObject;
-import org.ray.api.annotation.RayRemote;
 
 /**
  * Call a remote function from within another remote function.
@@ -12,7 +11,6 @@ public class Exercise03 {
   /**
    * A remote function which will call another remote function.
    */
-  @RayRemote
   public static String sayHelloWithWorld() {
     String ret = "hello";
     System.out.println(ret);
@@ -23,7 +21,6 @@ public class Exercise03 {
   /**
    * A remote function which will be called by another remote function.
    */
-  @RayRemote
   public static String sayWorld() {
     String ret = "world!";
     System.out.println(ret);

java/tutorial/src/main/java/org/ray/exercise/Exercise04.java

@@ -5,20 +5,17 @@ import java.util.List;
 import org.ray.api.Ray;
 import org.ray.api.RayObject;
 import org.ray.api.WaitResult;
-import org.ray.api.annotation.RayRemote;
 
 /**
  * Use Ray.wait to ignore stragglers
  */
 public class Exercise04 {
 
-  @RayRemote
   public static String f1() {
     System.out.println("Executing f1");
     return "f1";
   }
 
-  @RayRemote
   public static String f2() {
     System.out.println("Executing f2");
     return "f2";
@@ -27,7 +24,6 @@ public class Exercise04 {
   /**
    * A slow remote function.
    */
-  @RayRemote
   public static String f3() {
     System.out.println("Executing f3");
     try {

java/tutorial/src/main/java/org/ray/exercise/Exercise05.java

@@ -3,7 +3,6 @@ package org.ray.exercise;
 import org.ray.api.Ray;
 import org.ray.api.RayActor;
 import org.ray.api.RayObject;
-import org.ray.api.annotation.RayRemote;
 
 /**
  * Show usage of actors.
@@ -16,9 +15,9 @@ public class Exercise05 {
       // `Ray.createActor` creates an actor instance.
       RayActor<Adder> adder = Ray.createActor(Adder::new, 0);
       // Use `Ray.call(actor, parameters)` to call an actor method.
-      RayObject<Integer> result1 = Ray.call(Adder::add, adder, 1);
+      RayObject<Integer> result1 = adder.call(Adder::add, 1);
       System.out.println(result1.get());
-      RayObject<Integer> result2 = Ray.call(Adder::add, adder, 10);
+      RayObject<Integer> result2 = adder.call(Adder::add, 10);
       System.out.println(result2.get());
     } catch (Throwable t) {
       t.printStackTrace();
@@ -30,8 +29,6 @@ public class Exercise05 {
   /**
    * An example actor.
    */
-  // `@RayRemote` annotation also converts a normal class to an actor.
-  @RayRemote
   public static class Adder {
 
     public Adder(int initValue) {