[Java] ID length fix (#6454)

java/api/src/main/java/org/ray/api/id/ActorId.java

@@ -6,7 +6,10 @@ import java.util.Arrays;
 import java.util.Random;
 
 public class ActorId extends BaseId implements Serializable {
-  public static final int LENGTH = 8;
+
+  private static final int UNIQUE_BYTES_LENGTH = 4;
+
+  public static final int LENGTH = JobId.LENGTH + UNIQUE_BYTES_LENGTH;
 
   public static final ActorId NIL = nil();
 

java/api/src/main/java/org/ray/api/id/JobId.java

@@ -10,10 +10,7 @@ import java.util.Arrays;
  */
 public class JobId extends BaseId implements Serializable {
 
-  // Note that the max value of a job id is NIL which value is (2^32 - 1).
-  public static final Long MAX_VALUE = (long) Math.pow(2, 32) - 1;
-
-  public static final int LENGTH = 4;
+  public static final int LENGTH = 2;
 
   public static final JobId NIL = genNil();
 
@@ -39,11 +36,17 @@ public class JobId extends BaseId implements Serializable {
   }
 
   public static JobId fromInt(int value) {
-    byte[] bytes = new byte[JobId.LENGTH];
+    if (value > Math.pow(256, JobId.LENGTH)) {
+      throw new IllegalArgumentException(
+          "The integer value is invalid for a JobId. Value: " + value);
+    }
+    byte[] bytes = new byte[Integer.BYTES];
     ByteBuffer wbb = ByteBuffer.wrap(bytes);
     wbb.order(ByteOrder.LITTLE_ENDIAN);
     wbb.putInt(value);
-    return new JobId(bytes);
+    wbb.flip();
+    wbb.limit(JobId.LENGTH);
+    return JobId.fromByteBuffer(wbb);
   }
 
   /**

java/api/src/main/java/org/ray/api/id/TaskId.java

@@ -2,16 +2,16 @@ package org.ray.api.id;
 
 import java.io.Serializable;
 import java.nio.ByteBuffer;
-import java.nio.ByteOrder;
 import java.util.Arrays;
-import java.util.Random;
 
 /**
  * Represents the id of a Ray task.
  */
 public class TaskId extends BaseId implements Serializable {
 
-  public static final int LENGTH = 14;
+  private static final int UNIQUE_BYTES_LENGTH = 8;
+
+  public static final int LENGTH = ActorId.LENGTH + UNIQUE_BYTES_LENGTH;
 
   public static final TaskId NIL = genNil();