1 files changed, 25 insertions, 23 deletions

diff --git a/media/java/android/mtp/MtpDevice.java b/media/java/android/mtp/MtpDevice.java
index 4082778986c6..6970cffa2c6e 100644
--- a/media/java/android/mtp/MtpDevice.java
+++ b/media/java/android/mtp/MtpDevice.java
@@ -48,7 +48,8 @@ public final class MtpDevice {
      *
      * @param device the {@link android.hardware.usb.UsbDevice} for the MTP or PTP device
      */
-    public MtpDevice(UsbDevice device) {
+    public MtpDevice(@NonNull UsbDevice device) {
+        Preconditions.checkNotNull(device);
         mDevice = device;
     }
 
@@ -61,7 +62,7 @@ public final class MtpDevice {
      * @param connection an open {@link android.hardware.usb.UsbDeviceConnection} for the device
      * @return true if the device was successfully opened.
      */
-    public boolean open(UsbDeviceConnection connection) {
+    public boolean open(@NonNull UsbDeviceConnection connection) {
         boolean result = native_open(mDevice.getDeviceName(), connection.getFileDescriptor());
         if (!result) {
             connection.close();
@@ -94,7 +95,7 @@ public final class MtpDevice {
      *
      * @return the device name
      */
-    public String getDeviceName() {
+    public @NonNull String getDeviceName() {
         return mDevice.getDeviceName();
     }
 
@@ -110,16 +111,16 @@ public final class MtpDevice {
     }
 
     @Override
-    public String toString() {
+    public @NonNull String toString() {
         return mDevice.getDeviceName();
     }
 
     /**
      * Returns the {@link MtpDeviceInfo} for this device
      *
-     * @return the device info
+     * @return the device info, or null if fetching device info fails
      */
-    public MtpDeviceInfo getDeviceInfo() {
+    public @Nullable MtpDeviceInfo getDeviceInfo() {
         return native_get_device_info();
     }
 
@@ -127,9 +128,9 @@ public final class MtpDevice {
      * Returns the list of IDs for all storage units on this device
      * Information about each storage unit can be accessed via {@link #getStorageInfo}.
      *
-     * @return the list of storage IDs
+     * @return the list of storage IDs, or null if fetching storage IDs fails
      */
-    public int[] getStorageIds() {
+    public @Nullable int[] getStorageIds() {
         return native_get_storage_ids();
     }
 
@@ -142,9 +143,9 @@ public final class MtpDevice {
      * @param format the format of the object to return, or zero for all formats
      * @param objectHandle the parent object to query, -1 for the storage root,
      *     or zero for all objects
-     * @return the object handles
+     * @return the object handles, or null if fetching object handles fails
      */
-    public int[] getObjectHandles(int storageId, int format, int objectHandle) {
+    public @Nullable int[] getObjectHandles(int storageId, int format, int objectHandle) {
         return native_get_object_handles(storageId, format, objectHandle);
     }
 
@@ -158,7 +159,7 @@ public final class MtpDevice {
      *      {@link MtpObjectInfo#getCompressedSize})
      * @return the object's data, or null if reading fails
      */
-    public byte[] getObject(int objectHandle, int objectSize) {
+    public @Nullable byte[] getObject(int objectHandle, int objectSize) {
         Preconditions.checkArgumentNonnegative(objectSize, "objectSize should not be negative");
         return native_get_object(objectHandle, objectSize);
     }
@@ -176,7 +177,7 @@ public final class MtpDevice {
      * @param buffer Array to write data.
      * @return Size of bytes that are actually read.
      */
-    public long getPartialObject(int objectHandle, long offset, long size, byte[] buffer)
+    public long getPartialObject(int objectHandle, long offset, long size, @NonNull byte[] buffer)
             throws IOException {
         return native_get_partial_object(objectHandle, offset, size, buffer);
     }
@@ -197,7 +198,7 @@ public final class MtpDevice {
      * @return Size of bytes that are actually read.
      * @see MtpConstants#OPERATION_GET_PARTIAL_OBJECT_64
      */
-    public long getPartialObject64(int objectHandle, long offset, long size, byte[] buffer)
+    public long getPartialObject64(int objectHandle, long offset, long size, @NonNull byte[] buffer)
             throws IOException {
         return native_get_partial_object_64(objectHandle, offset, size, buffer);
     }
@@ -212,7 +213,7 @@ public final class MtpDevice {
      * @param objectHandle handle of the object to read
      * @return the object's thumbnail, or null if reading fails
      */
-    public byte[] getThumbnail(int objectHandle) {
+    public @Nullable byte[] getThumbnail(int objectHandle) {
         return native_get_thumbnail(objectHandle);
     }
 
@@ -220,9 +221,9 @@ public final class MtpDevice {
      * Retrieves the {@link MtpStorageInfo} for a storage unit.
      *
      * @param storageId the ID of the storage unit
-     * @return the MtpStorageInfo
+     * @return the MtpStorageInfo, or null if fetching storage info fails
      */
-    public MtpStorageInfo getStorageInfo(int storageId) {
+    public @Nullable MtpStorageInfo getStorageInfo(int storageId) {
         return native_get_storage_info(storageId);
     }
 
@@ -230,9 +231,9 @@ public final class MtpDevice {
      * Retrieves the {@link MtpObjectInfo} for an object.
      *
      * @param objectHandle the handle of the object
-     * @return the MtpObjectInfo
+     * @return the MtpObjectInfo, or null if fetching object info fails
      */
-    public MtpObjectInfo getObjectInfo(int objectHandle) {
+    public @Nullable MtpObjectInfo getObjectInfo(int objectHandle) {
         return native_get_object_info(objectHandle);
     }
 
@@ -279,7 +280,7 @@ public final class MtpDevice {
      *      {@link android.os.Environment#getExternalStorageDirectory}
      * @return true if the file transfer succeeds
      */
-    public boolean importFile(int objectHandle, String destPath) {
+    public boolean importFile(int objectHandle, @NonNull String destPath) {
         return native_import_file(objectHandle, destPath);
     }
 
@@ -293,7 +294,7 @@ public final class MtpDevice {
      * @param descriptor file descriptor to write the data to for the file transfer.
      * @return true if the file transfer succeeds
      */
-    public boolean importFile(int objectHandle, ParcelFileDescriptor descriptor) {
+    public boolean importFile(int objectHandle, @NonNull ParcelFileDescriptor descriptor) {
         return native_import_file(objectHandle, descriptor.getFd());
     }
 
@@ -308,7 +309,8 @@ public final class MtpDevice {
      * @param descriptor file descriptor to read the data from.
      * @return true if the file transfer succeeds
      */
-    public boolean sendObject(int objectHandle, long size, ParcelFileDescriptor descriptor) {
+    public boolean sendObject(
+            int objectHandle, long size, @NonNull ParcelFileDescriptor descriptor) {
         return native_send_object(objectHandle, size, descriptor.getFd());
     }
 
@@ -319,9 +321,9 @@ public final class MtpDevice {
      * The returned {@link MtpObjectInfo} has the new object handle field filled in.
      *
      * @param info metadata of the entry
-     * @return object info of the created entry or null if the operation failed.
+     * @return object info of the created entry, or null if sending object info fails
      */
-    public MtpObjectInfo sendObjectInfo(MtpObjectInfo info) {
+    public @Nullable MtpObjectInfo sendObjectInfo(@NonNull MtpObjectInfo info) {
         return native_send_object_info(info);
     }