私人无效loadFiles（最后弦乐目录）{
        新的Thread（）{
            @覆盖
            公共无效的run（）{

                字符串的mpath =目录;
                进入direntEx = NULL;
                尝试 {
                    direntEx = mApi.metadata（的mpath，1000，空，真，空）;
                }赶上（DropboxException E）{
                    e.printStackTrace（）;
                }

                如果（direntEx.contents.size（）！= 0）{
                    对于（输入ENT：direntEx.contents）{
                        字符串名称= ent.fileName（）;
                          / *这里比较文件* /

                   }
                 }

                super.run（）;
            }

        }。开始（）;

    }
 

I am using following code to upload a file to Dropbox. But I want to check if the file exists on Dropbox already, to avoid duplications. So how can I check if a file already exists or not? As I am new to Android, I don't know what to do now

public class UploadFileToDropbox extends AsyncTask<Void, Void, Boolean>
{

    private DropboxAPI<?> dropbox;
    private String path;
    private Context context;

    public UploadFileToDropbox(Context context, DropboxAPI<?> dropbox,
                               String path) {
        this.context = context.getApplicationContext();
        this.dropbox = dropbox;
        this.path = path;
    }

    @Override
    protected Boolean doInBackground(Void... params) {
        final File tempDir = context.getCacheDir();
        File tempFile;
        FileWriter fr;
        try {
            tempFile = File.createTempFile("file", ".txt", tempDir);
            fr = new FileWriter(tempFile);
            fr.write("Test file uploaded using Dropbox API for Android");
            fr.close();

            FileInputStream fileInputStream = new FileInputStream(tempFile);
            dropbox.putFile(path + "sample.txt", fileInputStream,
                    tempFile.length(), null, null);
            tempFile.delete();
            return true;
        } catch (IOException e) {
            e.printStackTrace();
        } catch (DropboxException e) {
            e.printStackTrace();
        }
        return false;
    }

    @Override
    protected void onPostExecute(Boolean result) {
        if (result) {
            Toast.makeText(context, "File Uploaded Successfully!",
                    Toast.LENGTH_LONG).show();
        } else {
            Toast.makeText(context, "Failed to upload file", Toast.LENGTH_LONG)
                    .show();
        }
    }
}

private void loadFiles(final String directory) {
        new Thread() {
            @Override
            public void run() {

                String mPath = directory;
                Entry direntEx = null;
                try {
                    direntEx = mApi.metadata(mPath, 1000, null, true, null);
                } catch (DropboxException e) {
                    e.printStackTrace();
                }

                if (direntEx.contents.size() != 0) {
                    for (Entry ent : direntEx.contents) {
                        String name = ent.fileName();
                          /*Compare file here*/

                   }
                 }

                super.run();
            }

        }.start();

    }