diff --git a/core/api/test-current.txt b/core/api/test-current.txt
index 632b10f3330e8..909c8e4f1adc2 100644
--- a/core/api/test-current.txt
+++ b/core/api/test-current.txt
@@ -914,6 +914,8 @@ package android.hardware.devicestate {
     method @NonNull public int[] getSupportedStates();
     method public void removeDeviceStateListener(@NonNull android.hardware.devicestate.DeviceStateManager.DeviceStateListener);
     method @RequiresPermission(android.Manifest.permission.CONTROL_DEVICE_STATE) public void requestState(@NonNull android.hardware.devicestate.DeviceStateRequest, @Nullable java.util.concurrent.Executor, @Nullable android.hardware.devicestate.DeviceStateRequest.Callback);
+    field public static final int MAXIMUM_DEVICE_STATE = 255; // 0xff
+    field public static final int MINIMUM_DEVICE_STATE = 0; // 0x0
   }
 
   public static interface DeviceStateManager.DeviceStateListener {
diff --git a/core/java/android/hardware/devicestate/DeviceStateManager.java b/core/java/android/hardware/devicestate/DeviceStateManager.java
index f175e7b00b7e2..2d4b2ccd75145 100644
--- a/core/java/android/hardware/devicestate/DeviceStateManager.java
+++ b/core/java/android/hardware/devicestate/DeviceStateManager.java
@@ -42,6 +42,12 @@ public final class DeviceStateManager {
      */
     public static final int INVALID_DEVICE_STATE = -1;
 
+    /** The minimum allowed device state identifier. */
+    public static final int MINIMUM_DEVICE_STATE = 0;
+
+    /** The maximum allowed device state identifier. */
+    public static final int MAXIMUM_DEVICE_STATE = 255;
+
     private final DeviceStateManagerGlobal mGlobal;
 
     /** @hide */
diff --git a/services/core/java/com/android/server/devicestate/DeviceState.java b/services/core/java/com/android/server/devicestate/DeviceState.java
index e496d77deaf5a..e693bcc93f8f5 100644
--- a/services/core/java/com/android/server/devicestate/DeviceState.java
+++ b/services/core/java/com/android/server/devicestate/DeviceState.java
@@ -16,9 +16,14 @@
 
 package com.android.server.devicestate;
 
+import static android.hardware.devicestate.DeviceStateManager.MAXIMUM_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MINIMUM_DEVICE_STATE;
+
 import android.annotation.IntRange;
 import android.annotation.NonNull;
 
+import com.android.internal.util.Preconditions;
+
 import java.util.Objects;
 
 /**
@@ -35,24 +40,25 @@ import java.util.Objects;
  */
 public final class DeviceState {
     /** Unique identifier for the device state. */
-    @IntRange(from = 0)
+    @IntRange(from = MINIMUM_DEVICE_STATE, to = MAXIMUM_DEVICE_STATE)
     private final int mIdentifier;
 
     /** String description of the device state. */
     @NonNull
     private final String mName;
 
-    public DeviceState(@IntRange(from = 0) int identifier,
+    public DeviceState(
+            @IntRange(from = MINIMUM_DEVICE_STATE, to = MAXIMUM_DEVICE_STATE) int identifier,
             @NonNull String name) {
-        if (identifier < 0) {
-            throw new IllegalArgumentException("Identifier must be greater than or equal to zero.");
-        }
+        Preconditions.checkArgumentInRange(identifier, MINIMUM_DEVICE_STATE, MAXIMUM_DEVICE_STATE,
+                "identifier");
+
         mIdentifier = identifier;
         mName = name;
     }
 
     /** Returns the unique identifier for the device state. */
-    @IntRange(from = 0)
+    @IntRange(from = MINIMUM_DEVICE_STATE, to = MAXIMUM_DEVICE_STATE)
     public int getIdentifier() {
         return mIdentifier;
     }
diff --git a/services/core/java/com/android/server/devicestate/DeviceStateManagerService.java b/services/core/java/com/android/server/devicestate/DeviceStateManagerService.java
index 984a17694e07a..b3a6f263953f9 100644
--- a/services/core/java/com/android/server/devicestate/DeviceStateManagerService.java
+++ b/services/core/java/com/android/server/devicestate/DeviceStateManagerService.java
@@ -17,6 +17,8 @@
 package com.android.server.devicestate;
 
 import static android.Manifest.permission.CONTROL_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MAXIMUM_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MINIMUM_DEVICE_STATE;
 import static android.hardware.devicestate.DeviceStateRequest.FLAG_CANCEL_WHEN_BASE_CHANGES;
 
 import android.annotation.IntRange;
@@ -89,7 +91,7 @@ public final class DeviceStateManagerService extends SystemService {
     // the current state after the initial callback from the DeviceStateProvider.
     @GuardedBy("mLock")
     @NonNull
-    private DeviceState mCommittedState = new DeviceState(0, "UNSET");
+    private DeviceState mCommittedState = new DeviceState(MINIMUM_DEVICE_STATE, "UNSET");
     // The device state that is currently awaiting callback from the policy to be committed.
     @GuardedBy("mLock")
     @NonNull
@@ -598,8 +600,9 @@ public final class DeviceStateManagerService extends SystemService {
         }
 
         @Override
-        public void onStateChanged(@IntRange(from = 0) int identifier) {
-            if (identifier < 0) {
+        public void onStateChanged(
+                @IntRange(from = MINIMUM_DEVICE_STATE, to = MAXIMUM_DEVICE_STATE) int identifier) {
+            if (identifier < MINIMUM_DEVICE_STATE || identifier > MAXIMUM_DEVICE_STATE) {
                 throw new IllegalArgumentException("Invalid identifier: " + identifier);
             }
 
diff --git a/services/core/java/com/android/server/devicestate/DeviceStateProvider.java b/services/core/java/com/android/server/devicestate/DeviceStateProvider.java
index 2d4377f820fd8..109bf6358e8bc 100644
--- a/services/core/java/com/android/server/devicestate/DeviceStateProvider.java
+++ b/services/core/java/com/android/server/devicestate/DeviceStateProvider.java
@@ -16,6 +16,9 @@
 
 package com.android.server.devicestate;
 
+import static android.hardware.devicestate.DeviceStateManager.MAXIMUM_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MINIMUM_DEVICE_STATE;
+
 import android.annotation.IntRange;
 
 /**
@@ -65,8 +68,10 @@ public interface DeviceStateProvider {
          *
          * @param identifier the identifier of the new device state.
          *
-         * @throws IllegalArgumentException if the state is less than 0.
+         * @throws IllegalArgumentException if the state is less than {@link MINIMUM_DEVICE_STATE}
+         * or greater than {@link MAXIMUM_DEVICE_STATE}.
          */
-        void onStateChanged(@IntRange(from = 0) int identifier);
+        void onStateChanged(
+                @IntRange(from = MINIMUM_DEVICE_STATE, to = MAXIMUM_DEVICE_STATE) int identifier);
     }
 }
diff --git a/services/core/java/com/android/server/policy/DeviceStateProviderImpl.java b/services/core/java/com/android/server/policy/DeviceStateProviderImpl.java
index ac358db519394..4e1065a9d3af7 100644
--- a/services/core/java/com/android/server/policy/DeviceStateProviderImpl.java
+++ b/services/core/java/com/android/server/policy/DeviceStateProviderImpl.java
@@ -17,6 +17,7 @@
 package com.android.server.policy;
 
 import static android.hardware.devicestate.DeviceStateManager.INVALID_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MINIMUM_DEVICE_STATE;
 
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -84,7 +85,8 @@ public final class DeviceStateProviderImpl implements DeviceStateProvider,
     private static final BooleanSupplier TRUE_BOOLEAN_SUPPLIER = () -> true;
 
     @VisibleForTesting
-    static final DeviceState DEFAULT_DEVICE_STATE = new DeviceState(0, "DEFAULT");
+    static final DeviceState DEFAULT_DEVICE_STATE = new DeviceState(MINIMUM_DEVICE_STATE,
+            "DEFAULT");
 
     private static final String VENDOR_CONFIG_FILE_PATH = "etc/devicestate/";
     private static final String DATA_CONFIG_FILE_PATH = "system/devicestate/";
diff --git a/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
index 1a2266139405d..a078a77b4498a 100644
--- a/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
+++ b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateManagerServiceTest.java
@@ -52,7 +52,8 @@ import javax.annotation.Nullable;
 public final class DeviceStateManagerServiceTest {
     private static final DeviceState DEFAULT_DEVICE_STATE = new DeviceState(0, "DEFAULT");
     private static final DeviceState OTHER_DEVICE_STATE = new DeviceState(1, "OTHER");
-    private static final DeviceState UNSUPPORTED_DEVICE_STATE = new DeviceState(999, "UNSUPPORTED");
+    // A device state that is not reported as being supported for the default test provider.
+    private static final DeviceState UNSUPPORTED_DEVICE_STATE = new DeviceState(255, "UNSUPPORTED");
 
     private TestDeviceStatePolicy mPolicy;
     private TestDeviceStateProvider mProvider;
diff --git a/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateTest.java b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateTest.java
new file mode 100644
index 0000000000000..b5c8053ad77ea
--- /dev/null
+++ b/services/tests/servicestests/src/com/android/server/devicestate/DeviceStateTest.java
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.devicestate;
+
+import static android.hardware.devicestate.DeviceStateManager.MAXIMUM_DEVICE_STATE;
+import static android.hardware.devicestate.DeviceStateManager.MINIMUM_DEVICE_STATE;
+
+import static org.testng.Assert.assertEquals;
+import static org.testng.Assert.assertNull;
+import static org.testng.Assert.assertThrows;
+
+import android.platform.test.annotations.Presubmit;
+
+import androidx.test.runner.AndroidJUnit4;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+/**
+ * Unit tests for {@link DeviceState}.
+ * <p/>
+ * Run with <code>atest DeviceStateTest</code>.
+ */
+@Presubmit
+@RunWith(AndroidJUnit4.class)
+public final class DeviceStateTest {
+    @Test
+    public void testConstruct() {
+        final DeviceState state = new DeviceState(MINIMUM_DEVICE_STATE /* identifier */,
+                "CLOSED" /* name */);
+        assertEquals(state.getIdentifier(), MINIMUM_DEVICE_STATE);
+        assertEquals(state.getName(), "CLOSED");
+    }
+
+    @Test
+    public void testConstruct_nullName() {
+        final DeviceState state = new DeviceState(MAXIMUM_DEVICE_STATE /* identifier */,
+                null /* name */);
+        assertEquals(state.getIdentifier(), MAXIMUM_DEVICE_STATE);
+        assertNull(state.getName());
+    }
+
+    @Test
+    public void testConstruct_tooLargeIdentifier() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            final DeviceState state = new DeviceState(MAXIMUM_DEVICE_STATE + 1 /* identifier */,
+                    null /* name */);
+        });
+    }
+
+    @Test
+    public void testConstruct_tooSmallIdentifier() {
+        assertThrows(IllegalArgumentException.class, () -> {
+            final DeviceState state = new DeviceState(MINIMUM_DEVICE_STATE - 1 /* identifier */,
+                    null /* name */);
+        });
+    }
+}