Android Google API错误：＆＃34;在Task中的continueWithTask（A，B）无法应用于continueWithTask（C，B）＆＃34;

Question

我正在创建一个应用程序，该应用程序应该使用相关API将文件保存到Google云端硬盘。我已管理登录，现在我希望该应用在Google云端硬盘中创建一个文件夹，然后将该文件写入该文件夹。

由于Drive API是异步的，我试图用continueWithTask（）连接几个任务。在以下代码中对continueWithTask（）的最后一次调用引发了Android Studio错误消息：＆＃34; continueWithTask（... Continuation＆lt; ... DriveFolder，... Task＆lt; ... DriveFile＆gt;＆gt;）在Task中无法应用于（匿名...延续＆lt; ... DriveContents，...任务＆lt; ... DriveFile＆gt;＆gt;）＆＃34;。

我不知道为什么＆＃34; DriveFolder＆＃34;出现在上面的错误消息中，因为在最后一个continueWithTask（）参数中没有使用DriveFolder。唯一的DriveFolder是m_DriveFolder类成员。

有人可以帮我理解错误的位置吗？

void SyncToDrive()
{
   Task<DriveFolder> l_TaskSyncToDrive;

   // Gets the resource client
   m_DriveResourceClient = Drive.getDriveResourceClient(this, m_GoogleSignInAccount);

   //Creates the new folder
   l_TaskSyncToDrive =
      m_DriveResourceClient
         .getRootFolder()
         .continueWithTask(new Continuation<DriveFolder, Task<DriveFolder>>()
         {
            @Override
            public Task<DriveFolder> then(@NonNull Task<DriveFolder> task) throws Exception
            {
               DriveFolder parentFolder = task.getResult();
               MetadataChangeSet changeSet = new MetadataChangeSet.Builder()
                  .setTitle("MyFolder")
                  .setMimeType(DriveFolder.MIME_TYPE)
                  .setStarred(true)
                  .build();
               return m_DriveResourceClient.createFolder(parentFolder, changeSet);
            }
         })
         .addOnSuccessListener(this,
                               new OnSuccessListener<DriveFolder>()
                               {
                                  @Override
                                  public void onSuccess(DriveFolder driveFolder)
                                  {
                                     Toast toast = Toast.makeText(getApplicationContext(), driveFolder.getDriveId().encodeToString(),
                                                                  Toast.LENGTH_SHORT);
                                     toast.show();
                                  }
                               })
         .addOnFailureListener(this,
                               new OnFailureListener()
                               {
                                  @Override
                                  public void onFailure(@NonNull Exception e)
                                  {
                                     Log.e("D103", "Unable to create folder", e);
                                     Toast toast = Toast.makeText(getApplicationContext(), e.getMessage(),
                                                                  Toast.LENGTH_SHORT);
                                     toast.show();
                                  }
                               });


   // Creates the contents
   l_TaskSyncToDrive.continueWithTask(new Continuation<DriveFolder, Task<DriveContents>>()
                                      {
                                         @Override
                                         public Task<DriveContents> then(@NonNull Task<DriveFolder> p_DriveFolder) throws Exception
                                         {
                                            m_DriveFolder = p_DriveFolder.getResult();

                                            return m_DriveResourceClient.createContents();
                                         }
                                      });

   // Creates the file
   l_TaskSyncToDrive.continueWithTask(new Continuation<DriveContents, Task<DriveFile>>()
                                      {
                                         @Override
                                         public Task<DriveFile> then(@NonNull Task<DriveContents> p_DriveContents) throws Exception
                                         {
                                            DriveContents        l_DriveContents;
                                            OutputStream         l_OutputStream;
                                            DataOutputStream     l_DataOutputStream;

                                            l_DriveContents = p_DriveContents.getResult();
                                            l_OutputStream = l_DriveContents.getOutputStream();
                                            l_DataOutputStream = new DataOutputStream(l_OutputStream);

                                            if(!(SafeApplication.m_FileManager.ExportFile(l_DataOutputStream, SafeApplication.m_Elements)))
                                            {
                                               // TODO handle error
                                            }
                                            MetadataChangeSet l_ChangeSet = new MetadataChangeSet.Builder()
                                               .setTitle("MyFileName")
                                               .setMimeType("application/octet-stream")
                                               .build();

                                            return m_DriveResourceClient.createFile(m_DriveFolder, l_ChangeSet, l_DriveContents);
                                         }
                                      })
      .addOnFailureListener(new OnFailureListener()
                            {
                               @Override
                               public void onFailure(@NonNull Exception e)
                               {
                                  Log.w("D102", "Failed to create file.", e);
                                  Toast toast = Toast.makeText(getApplicationContext(), e.getMessage(),
                                                               Toast.LENGTH_SHORT);
                                  toast.show();
                               }
                            });
}

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