Code review comment: Since these are examples we should just use the long primitive instead of the Long object. When our API uses the Long object we should use Long.

Code under review:
public static void main(String[] args) throws Exception {

        /**
         * From the Azure portal, get your Storage account's name and account key.
         */
        String accountName = getAccountName();
        String accountKey = getAccountKey();

        /**
         * Use your Storage account's name and key to create a credential object; this is used to access your account.
         */
        SharedKeyCredential credential = new SharedKeyCredential(accountName, accountKey);

        /**
         * From the Azure portal, get your Storage account blob service URL endpoint.
         * The URL typically looks like this:
         */
        String endPoint = String.format(Locale.ROOT, "https:

        /**
         * Create a StorageClient object that wraps the service endpoint, credential and a request pipeline.
         * Now you can use the storageClient to perform various container and blob operations.
         */
        StorageClient storageClient = StorageClient.storageClientBuilder().endpoint(endPoint).credential(credential).buildClient();


        /**
         * This example shows several common operations just to get you started.
         */


        /**
         * Create a client that references a to-be-created container in your Azure Storage account. This returns a
         * ContainerClient uses the same endpoint, credential and pipeline from storageClient.
         * Note that container names require lowercase.
         */
        ContainerClient containerClient = storageClient.getContainerClient("myjavacontainerparallelupload" + System.currentTimeMillis());

        /**
         * Create a container in Storage blob account.
         */
        containerClient.create();

        /**
         * Create a BlockBlobClient object that wraps a blob's endpoint and a default pipeline, the blockBlobClient give us access to upload the file.
         */
        String filename = "BigFile.bin";
        BlockBlobClient blobClient = containerClient.getBlockBlobClient(filename);

        /**
         * Create the empty uploadFile and downloadFile.
         */
        File largeFile = createTempEmptyFile(filename);

        File downloadFile = createTempEmptyFile("downloadFile.bin");

        /**
         * Generate random things to uploadFile, which makes the file with size of 100MB.
         */
        Long fileSize = 100 * 1024 * 1024L;
        createTempFileWithFileSize(largeFile, fileSize);

        /**
         * Upload the large file to storage blob.
         */
        blobClient.uploadFromFile(largeFile.getPath());

        /**
         * Download the large file from storage blob to the local downloadFile path.
         */
        blobClient.downloadToFile(downloadFile.getPath());

        /**
         * Check the files are same after the round-trip.
         */
        if (Files.exists(downloadFile.toPath()) && Files.exists(largeFile.toPath())) {
            checkTwoFilesAreTheSame(largeFile, downloadFile);
            System.out.println("The file we upload is the same as the one we download.");
        } else {
            throw new RuntimeException("Did not find the upload or download file.");
        }

        /**
         * Clean up the local files and storage container.
         */
        containerClient.delete();
        Files.deleteIfExists(largeFile.toPath());
        Files.deleteIfExists(downloadFile.toPath());
    }

Line commented on: Long fileSize = 100 * 1024 * 1024L;

Revised code:
public static void main(String[] args) throws Exception {

        /**
         * From the Azure portal, get your Storage account's name and account key.
         */
        String accountName = getAccountName();
        String accountKey = getAccountKey();

        /**
         * Use your Storage account's name and key to create a credential object; this is used to access your account.
         */
        SharedKeyCredential credential = new SharedKeyCredential(accountName, accountKey);

        /**
         * From the Azure portal, get your Storage account blob service URL endpoint.
         * The URL typically looks like this:
         */
        String endPoint = String.format(Locale.ROOT, "https:

        /**
         * Create a StorageClient object that wraps the service endpoint, credential and a request pipeline.
         * Now you can use the storageClient to perform various container and blob operations.
         */
        StorageClient storageClient = StorageClient.storageClientBuilder().endpoint(endPoint).credential(credential).buildClient();


        /**
         * This example shows several common operations just to get you started.
         */


        /**
         * Create a client that references a to-be-created container in your Azure Storage account. This returns a
         * ContainerClient uses the same endpoint, credential and pipeline from storageClient.
         * Note that container names require lowercase.
         */
        ContainerClient containerClient = storageClient.getContainerClient("myjavacontainerparallelupload" + System.currentTimeMillis());

        /**
         * Create a container in Storage blob account.
         */
        containerClient.create();

        /**
         * Create a BlockBlobClient object that wraps a blob's endpoint and a default pipeline, the blockBlobClient give us access to upload the file.
         */
        String filename = "BigFile.bin";
        BlockBlobClient blobClient = containerClient.getBlockBlobClient(filename);

        /**
         * Create the empty uploadFile and downloadFile.
         */
        File largeFile = createTempEmptyFile(filename);

        File downloadFile = createTempEmptyFile("downloadFile.bin");

        /**
         * Generate random things to uploadFile, which makes the file with size of 100MB.
         */
        long fileSize = 100 * 1024 * 1024L;
        createTempFileWithFileSize(largeFile, fileSize);

        /**
         * Upload the large file to storage blob.
         */
        blobClient.uploadFromFile(largeFile.getPath());

        /**
         * Download the large file from storage blob to the local downloadFile path.
         */
        blobClient.downloadToFile(downloadFile.getPath());

        /**
         * Check the files are same after the round-trip.
         */
        if (Files.exists(downloadFile.toPath()) && Files.exists(largeFile.toPath())) {
            checkTwoFilesAreTheSame(largeFile, downloadFile);
            System.out.println("The file we upload is the same as the one we download.");
        } else {
            throw new RuntimeException("Did not find the upload or download file.");
        }

        /**
         * Clean up the local files and storage container.
         */
        containerClient.delete();
        Files.deleteIfExists(largeFile.toPath());
        Files.deleteIfExists(downloadFile.toPath());
    }