diff --git a/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java b/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
index bfbf64d81..117153423 100644
--- a/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
+++ b/java/runtime/src/main/java/org/ray/runtime/AbstractRayRuntime.java
@@ -113,8 +113,7 @@ public abstract class AbstractRayRuntime implements RayRuntime {
       int numObjectIds = objectIds.size();
 
       // Do an initial fetch for remote objects.
-      List<List<UniqueId>> fetchBatches =
-          splitIntoBatches(objectIds, FETCH_BATCH_SIZE);
+      List<List<UniqueId>> fetchBatches = splitIntoBatches(objectIds);
       for (List<UniqueId> batch : fetchBatches) {
         rayletClient.fetchOrReconstruct(batch, true, workerContext.getCurrentTaskId());
       }
@@ -139,8 +138,7 @@ public abstract class AbstractRayRuntime implements RayRuntime {
       while (unreadys.size() > 0) {
         retryCounter++;
         List<UniqueId> unreadyList = new ArrayList<>(unreadys.keySet());
-        List<List<UniqueId>> reconstructBatches =
-            splitIntoBatches(unreadyList, FETCH_BATCH_SIZE);
+        List<List<UniqueId>> reconstructBatches = splitIntoBatches(unreadyList);
 
         for (List<UniqueId> batch : reconstructBatches) {
           rayletClient.fetchOrReconstruct(batch, false, workerContext.getCurrentTaskId());
@@ -198,12 +196,12 @@ public abstract class AbstractRayRuntime implements RayRuntime {
     rayletClient.freePlasmaObjects(objectIds, localOnly);
   }
 
-  private List<List<UniqueId>> splitIntoBatches(List<UniqueId> objectIds, int batchSize) {
+  private List<List<UniqueId>> splitIntoBatches(List<UniqueId> objectIds) {
     List<List<UniqueId>> batches = new ArrayList<>();
     int objectsSize = objectIds.size();
 
-    for (int i = 0; i < objectsSize; i += batchSize) {
-      int endIndex = i + batchSize;
+    for (int i = 0; i < objectsSize; i += FETCH_BATCH_SIZE) {
+      int endIndex = i + FETCH_BATCH_SIZE;
       List<UniqueId> batchIds = (endIndex < objectsSize)
           ? objectIds.subList(i, endIndex)
           : objectIds.subList(i, objectsSize);
@@ -256,17 +254,6 @@ public abstract class AbstractRayRuntime implements RayRuntime {
     return (RayActor<T>) actor;
   }
 
-  /**
-   * Generate the return ids of a task.
-   */
-  private UniqueId[] genReturnIds(UniqueId taskId, int numReturns) {
-    UniqueId[] ret = new UniqueId[numReturns];
-    for (int i = 0; i < numReturns; i++) {
-      ret[i] = UniqueIdUtil.computeReturnId(taskId, i + 1);
-    }
-    return ret;
-  }
-
   /**
    * Create the task specification.
    * @param func The target remote function.
@@ -280,7 +267,7 @@ public abstract class AbstractRayRuntime implements RayRuntime {
     UniqueId taskId = rayletClient.generateTaskId(workerContext.getCurrentDriverId(),
         workerContext.getCurrentTaskId(), workerContext.nextTaskIndex());
     int numReturns = actor.getId().isNil() ? 1 : 2;
-    UniqueId[] returnIds = genReturnIds(taskId, numReturns);
+    UniqueId[] returnIds = UniqueIdUtil.genReturnIds(taskId, numReturns);
 
     UniqueId actorCreationId = UniqueId.NIL;
     if (isActorCreationTask) {
diff --git a/java/runtime/src/main/java/org/ray/runtime/DefaultRayRuntimeFactory.java b/java/runtime/src/main/java/org/ray/runtime/DefaultRayRuntimeFactory.java
index 366937b10..7223fa28e 100644
--- a/java/runtime/src/main/java/org/ray/runtime/DefaultRayRuntimeFactory.java
+++ b/java/runtime/src/main/java/org/ray/runtime/DefaultRayRuntimeFactory.java
@@ -1,13 +1,9 @@
 package org.ray.runtime;
 
-import com.google.common.base.Strings;
-import java.lang.reflect.Field;
-import java.util.stream.Collectors;
 import org.ray.api.runtime.RayRuntime;
 import org.ray.api.runtime.RayRuntimeFactory;
 import org.ray.runtime.config.RayConfig;
 import org.ray.runtime.config.RunMode;
-import org.ray.runtime.util.logger.RayLog;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -20,7 +16,6 @@ public class DefaultRayRuntimeFactory implements RayRuntimeFactory {
 
   @Override
   public RayRuntime createRayRuntime() {
-    RayLog.init();
     RayConfig rayConfig = RayConfig.create();
     try {
       AbstractRayRuntime runtime;
diff --git a/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java b/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
index 139abdf63..386202d38 100644
--- a/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
+++ b/java/runtime/src/main/java/org/ray/runtime/RayNativeRuntime.java
@@ -31,7 +31,7 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
     super(rayConfig);
   }
 
-  private void resetLibaryPath() {
+  private void resetLibraryPath() {
     String path = System.getProperty("java.library.path");
     if (Strings.isNullOrEmpty(path)) {
       path = "";
@@ -60,7 +60,7 @@ public final class RayNativeRuntime extends AbstractRayRuntime {
   public void start() throws Exception {
     // Load native libraries.
     try {
-      resetLibaryPath();
+      resetLibraryPath();
       System.loadLibrary("raylet_library_java");
       System.loadLibrary("plasma_java");
     } catch (Exception e) {
diff --git a/java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java b/java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java
index b3df8d1cb..b804a481f 100644
--- a/java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java
+++ b/java/runtime/src/main/java/org/ray/runtime/raylet/RayletClientImpl.java
@@ -37,7 +37,7 @@ public class RayletClientImpl implements RayletClient {
   );
 
   /**
-   * Point to c++'s local scheduler client.
+   * The pointer to c++'s local scheduler client.
    */
   private long client = 0;
 
diff --git a/java/runtime/src/main/java/org/ray/runtime/runner/worker/DefaultWorker.java b/java/runtime/src/main/java/org/ray/runtime/runner/worker/DefaultWorker.java
index e67ec1967..6fd3ea0e7 100644
--- a/java/runtime/src/main/java/org/ray/runtime/runner/worker/DefaultWorker.java
+++ b/java/runtime/src/main/java/org/ray/runtime/runner/worker/DefaultWorker.java
@@ -16,14 +16,10 @@ public class DefaultWorker {
     try {
       System.setProperty("ray.worker.mode", "WORKER");
       Ray.init();
-    } catch (Exception e) {
-      LOGGER.error("Worker failed to start.", e);
-    }
-    LOGGER.info("Worker started.");
-    try {
+      LOGGER.info("Worker started.");
       ((AbstractRayRuntime)Ray.internal()).loop();
     } catch (Exception e) {
-      LOGGER.error("Error occurred in worker.", e);
+      LOGGER.error("Failed to start worker.", e);
     }
   }
 }
diff --git a/java/runtime/src/main/java/org/ray/runtime/util/ObjectUtil.java b/java/runtime/src/main/java/org/ray/runtime/util/ObjectUtil.java
deleted file mode 100644
index 6b9df2993..000000000
--- a/java/runtime/src/main/java/org/ray/runtime/util/ObjectUtil.java
+++ /dev/null
@@ -1,25 +0,0 @@
-package org.ray.runtime.util;
-
-import java.lang.reflect.InvocationTargetException;
-
-public class ObjectUtil {
-
-  public static <T> T newObject(Class<T> cls) {
-    try {
-      return cls.getConstructor().newInstance();
-    } catch (InstantiationException | IllegalAccessException | NoSuchMethodException
-        | InvocationTargetException e) {
-      e.printStackTrace();
-      return null;
-    }
-  }
-
-  public static boolean[] toBooleanArray(Object[] vs) {
-    boolean[] nvs = new boolean[vs.length];
-    for (int i = 0; i < vs.length; i++) {
-      nvs[i] = (boolean) vs[i];
-    }
-    return nvs;
-  }
-
-}
diff --git a/java/runtime/src/main/java/org/ray/runtime/util/UniqueIdUtil.java b/java/runtime/src/main/java/org/ray/runtime/util/UniqueIdUtil.java
index d7b347945..021279924 100644
--- a/java/runtime/src/main/java/org/ray/runtime/util/UniqueIdUtil.java
+++ b/java/runtime/src/main/java/org/ray/runtime/util/UniqueIdUtil.java
@@ -71,6 +71,21 @@ public class UniqueIdUtil {
     return new UniqueId(taskId);
   }
 
+  /**
+   * Generate the return ids of a task.
+   *
+   * @param taskId The ID of the task that generates returnsIds.
+   * @param numReturns The number of returnIds.
+   * @return The Return Ids of this task.
+   */
+  public static UniqueId[] genReturnIds(UniqueId taskId, int numReturns) {
+    UniqueId[] ret = new UniqueId[numReturns];
+    for (int i = 0; i < numReturns; i++) {
+      ret[i] = UniqueIdUtil.computeReturnId(taskId, i + 1);
+    }
+    return ret;
+  }
+
   public static byte[][] getIdBytes(List<UniqueId> objectIds) {
     int size = objectIds.size();
     byte[][] ids = new byte[size][];
diff --git a/java/runtime/src/main/java/org/ray/runtime/util/logger/RayLog.java b/java/runtime/src/main/java/org/ray/runtime/util/logger/RayLog.java
deleted file mode 100644
index efc38d1db..000000000
--- a/java/runtime/src/main/java/org/ray/runtime/util/logger/RayLog.java
+++ /dev/null
@@ -1,27 +0,0 @@
-package org.ray.runtime.util.logger;
-
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * loggers in Ray.
- *   1. core logger is used for internal Ray status logging.
- *   2. rapp for ray applications logging.
- */
-public class RayLog {
-
-  /**
-   * for ray itself.
-   */
-  public static Logger core;
-
-  /**
-   * for ray app.
-   */
-  public static Logger rapp;
-
-  public static void init() {
-    core = LoggerFactory.getLogger("core");
-    rapp = core;
-  }
-}
diff --git a/java/test/src/main/java/org/ray/api/benchmark/RayBenchmarkTest.java b/java/test/src/main/java/org/ray/api/benchmark/RayBenchmarkTest.java
index ab73dd214..8e96b78fa 100644
--- a/java/test/src/main/java/org/ray/api/benchmark/RayBenchmarkTest.java
+++ b/java/test/src/main/java/org/ray/api/benchmark/RayBenchmarkTest.java
@@ -12,7 +12,6 @@ import org.ray.api.RayActor;
 import org.ray.api.RayObject;
 import org.ray.api.annotation.RayRemote;
 import org.ray.api.test.BaseTest;
-import org.ray.runtime.util.logger.RayLog;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
diff --git a/java/test/src/main/java/org/ray/api/test/RayMethodsTest.java b/java/test/src/main/java/org/ray/api/test/RayMethodsTest.java
index a612ef7c2..8fb430bdc 100644
--- a/java/test/src/main/java/org/ray/api/test/RayMethodsTest.java
+++ b/java/test/src/main/java/org/ray/api/test/RayMethodsTest.java
@@ -8,7 +8,6 @@ import org.junit.Test;
 import org.ray.api.Ray;
 import org.ray.api.RayObject;
 import org.ray.api.WaitResult;
-import org.ray.runtime.util.logger.RayLog;
 
 /**
  * Integration test for Ray.*
@@ -30,8 +29,6 @@ public class RayMethodsTest extends BaseTest {
     double f1 = f1Id.get();
     Object n1 = n1Id.get();
 
-    RayLog.rapp.info("Strings: " + ss.get(0) + ss.get(1) + " int: " + i1 + " double: " + f1
-        + " null: " + n1);
     Assert.assertEquals("Hello World!", ss.get(0) + ss.get(1));
     Assert.assertEquals(1, i1);
     Assert.assertEquals(3.14, f1, Double.MIN_NORMAL);