How to get the size of a file in MB (Megabytes)?

Use the length() method of the File class to return the size of the file in bytes.

// Get file from file name
File file = new File("U:\intranet_root\intranet\R1112B2.zip");

// Get length of file in bytes
long fileSizeInBytes = file.length();
// Convert the bytes to Kilobytes (1 KB = 1024 Bytes)
long fileSizeInKB = fileSizeInBytes / 1024;
// Convert the KB to MegaBytes (1 MB = 1024 KBytes)
long fileSizeInMB = fileSizeInKB / 1024;

if (fileSizeInMB > 27) {
  ...
}

You could combine the conversion into one step, but I've tried to fully illustrate the process.

Try following code:

File file = new File("infilename");

// Get the number of bytes in the file
long sizeInBytes = file.length();
//transform in MB
long sizeInMb = sizeInBytes / (1024 * 1024);

Example :

public static String getStringSizeLengthFile(long size) {

    DecimalFormat df = new DecimalFormat("0.00");

    float sizeKb = 1024.0f;
    float sizeMb = sizeKb * sizeKb;
    float sizeGb = sizeMb * sizeKb;
    float sizeTerra = sizeGb * sizeKb;


    if(size < sizeMb)
        return df.format(size / sizeKb)+ " Kb";
    else if(size < sizeGb)
        return df.format(size / sizeMb) + " Mb";
    else if(size < sizeTerra)
        return df.format(size / sizeGb) + " Gb";

    return "";
}