diff --git a/java/api/src/main/java/io/ray/api/placementgroup/PlacementGroup.java b/java/api/src/main/java/io/ray/api/placementgroup/PlacementGroup.java
index 9b4080deb..0c5b31b67 100644
--- a/java/api/src/main/java/io/ray/api/placementgroup/PlacementGroup.java
+++ b/java/api/src/main/java/io/ray/api/placementgroup/PlacementGroup.java
@@ -1,9 +1,57 @@
 package io.ray.api.placementgroup;
 
+import io.ray.api.id.PlacementGroupId;
+import java.util.List;
+import java.util.Map;
+
 /**
  * A placement group is used to place interdependent actors according to a specific strategy {@link
  * PlacementStrategy}. When a placement group is created, the corresponding actor slots and
  * resources are preallocated. A placement group consists of one or more bundles plus a specific
  * placement strategy.
  */
-public interface PlacementGroup {}
+public interface PlacementGroup {
+
+  /**
+   * Get the id of current placement group.
+   *
+   * @return Id of current placement group.
+   */
+  PlacementGroupId getId();
+
+  /**
+   * Get the name of current placement group.
+   *
+   * @return Name of current placement group.
+   */
+  String getName();
+
+  /**
+   * Get all bundles which key is resource name and value is resource value.
+   *
+   * @return All bundles of current placement group.
+   */
+  List<Map<String, Double>> getBundles();
+
+  /**
+   * Get the strategy of current placement group.
+   *
+   * @return Strategy of current placement group.
+   */
+  PlacementStrategy getStrategy();
+
+  /**
+   * Get the state of current placement group.
+   *
+   * @return Creation state of current placement group.
+   */
+  PlacementGroupState getState();
+
+  /**
+   * Wait for the placement group to be ready within the specified time.
+   *
+   * @param timeoutSeconds Timeout in seconds.
+   * @return True if the placement group is created. False otherwise.
+   */
+  boolean wait(int timeoutSeconds);
+}
diff --git a/java/runtime/src/main/java/io/ray/runtime/placementgroup/PlacementGroupImpl.java b/java/runtime/src/main/java/io/ray/runtime/placementgroup/PlacementGroupImpl.java
index 1d0d54084..55ca446f8 100644
--- a/java/runtime/src/main/java/io/ray/runtime/placementgroup/PlacementGroupImpl.java
+++ b/java/runtime/src/main/java/io/ray/runtime/placementgroup/PlacementGroupImpl.java
@@ -30,32 +30,32 @@ public class PlacementGroupImpl implements PlacementGroup {
     this.state = state;
   }
 
+  @Override
   public PlacementGroupId getId() {
     return id;
   }
 
+  @Override
   public String getName() {
     return name;
   }
 
+  @Override
   public List<Map<String, Double>> getBundles() {
     return bundles;
   }
 
+  @Override
   public PlacementStrategy getStrategy() {
     return strategy;
   }
 
+  @Override
   public PlacementGroupState getState() {
     return state;
   }
 
-  /**
-   * Wait for the placement group to be ready within the specified time.
-   *
-   * @param timeoutSeconds Timeout in seconds.
-   * @return True if the placement group is created. False otherwise.
-   */
+  @Override
   public boolean wait(int timeoutSeconds) {
     return Ray.internal().waitPlacementGroupReady(id, timeoutSeconds);
   }
diff --git a/java/test/src/main/java/io/ray/test/PlacementGroupTest.java b/java/test/src/main/java/io/ray/test/PlacementGroupTest.java
index 14bf0fd6a..edbd2c30e 100644
--- a/java/test/src/main/java/io/ray/test/PlacementGroupTest.java
+++ b/java/test/src/main/java/io/ray/test/PlacementGroupTest.java
@@ -7,7 +7,6 @@ import io.ray.api.placementgroup.PlacementGroup;
 import io.ray.api.placementgroup.PlacementGroupState;
 import io.ray.api.placementgroup.PlacementStrategy;
 import io.ray.runtime.exception.RayException;
-import io.ray.runtime.placementgroup.PlacementGroupImpl;
 import java.util.List;
 import org.testng.Assert;
 import org.testng.annotations.Test;
@@ -32,8 +31,7 @@ public class PlacementGroupTest extends BaseTest {
   // This test just creates a placement group with one bundle.
   // It's not comprehensive to test all placement group test cases.
   public void testCreateAndCallActor() {
-    PlacementGroupImpl placementGroup =
-        (PlacementGroupImpl) PlacementGroupTestUtils.createSimpleGroup();
+    PlacementGroup placementGroup = PlacementGroupTestUtils.createSimpleGroup();
     Assert.assertTrue(placementGroup.wait(10));
     Assert.assertEquals(placementGroup.getName(), "unnamed_group");
 
@@ -48,22 +46,18 @@ public class PlacementGroupTest extends BaseTest {
 
   @Test(groups = {"cluster"})
   public void testGetPlacementGroup() {
-    PlacementGroupImpl firstPlacementGroup =
-        (PlacementGroupImpl)
-            PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
-                "CPU", 1, PlacementStrategy.PACK, 1.0, "first_placement_group");
+    PlacementGroup firstPlacementGroup =
+        PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
+            "CPU", 1, PlacementStrategy.PACK, 1.0, "first_placement_group");
 
-    PlacementGroupImpl secondPlacementGroup =
-        (PlacementGroupImpl)
-            PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
-                "CPU", 1, PlacementStrategy.PACK, 1.0, "second_placement_group");
+    PlacementGroup secondPlacementGroup =
+        PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
+            "CPU", 1, PlacementStrategy.PACK, 1.0, "second_placement_group");
     Assert.assertTrue(firstPlacementGroup.wait(10));
     Assert.assertTrue(secondPlacementGroup.wait(10));
 
-    PlacementGroupImpl firstPlacementGroupRes =
-        (PlacementGroupImpl) Ray.getPlacementGroup((firstPlacementGroup).getId());
-    PlacementGroupImpl secondPlacementGroupRes =
-        (PlacementGroupImpl) Ray.getPlacementGroup((secondPlacementGroup).getId());
+    PlacementGroup firstPlacementGroupRes = Ray.getPlacementGroup((firstPlacementGroup).getId());
+    PlacementGroup secondPlacementGroupRes = Ray.getPlacementGroup((secondPlacementGroup).getId());
 
     Assert.assertNotNull(firstPlacementGroupRes);
     Assert.assertNotNull(secondPlacementGroupRes);
@@ -76,9 +70,9 @@ public class PlacementGroupTest extends BaseTest {
     List<PlacementGroup> allPlacementGroup = Ray.getAllPlacementGroups();
     Assert.assertEquals(allPlacementGroup.size(), 2);
 
-    PlacementGroupImpl placementGroupRes = (PlacementGroupImpl) allPlacementGroup.get(0);
+    PlacementGroup placementGroupRes = allPlacementGroup.get(0);
     Assert.assertNotNull(placementGroupRes.getId());
-    PlacementGroupImpl expectPlacementGroup =
+    PlacementGroup expectPlacementGroup =
         placementGroupRes.getId().equals(firstPlacementGroup.getId())
             ? firstPlacementGroup
             : secondPlacementGroup;
@@ -94,18 +88,16 @@ public class PlacementGroupTest extends BaseTest {
     PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
         "CPU", 1, PlacementStrategy.PACK, 1.0, "first_placement_group");
 
-    PlacementGroupImpl secondPlacementGroup =
-        (PlacementGroupImpl)
-            PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
-                "CPU", 1, PlacementStrategy.PACK, 1.0, "second_placement_group");
+    PlacementGroup secondPlacementGroup =
+        PlacementGroupTestUtils.createNameSpecifiedSimpleGroup(
+            "CPU", 1, PlacementStrategy.PACK, 1.0, "second_placement_group");
 
     List<PlacementGroup> allPlacementGroup = Ray.getAllPlacementGroups();
     Assert.assertEquals(allPlacementGroup.size(), 2);
 
     Ray.removePlacementGroup(secondPlacementGroup.getId());
 
-    PlacementGroupImpl removedPlacementGroup =
-        (PlacementGroupImpl) Ray.getPlacementGroup((secondPlacementGroup).getId());
+    PlacementGroup removedPlacementGroup = Ray.getPlacementGroup((secondPlacementGroup).getId());
     Assert.assertEquals(removedPlacementGroup.getState(), PlacementGroupState.REMOVED);
 
     // Wait for placement group after it is removed.