WARNING: File.mkdir() is ignored

Question

I've created a basic Audio Recording App using Media Recorder API's. I'm trying to create a folder in the SD card and to save my recorded files to that folder. I'm getting this warning with following code.

File.mkdir() is ignored

    // Assign random number to avoid audio file from overwriting
    Long tsLong = System.currentTimeMillis()/1000;

    // Specify a Location for the recorded file to be stored in the SD card
    mFileName = Environment.getExternalStorageDirectory().getAbsolutePath() + "/AudioRecordTest/";
    File path = new File(mFileName);
    if(!path.exists()) {
        path.mkdir();
    }
    mFileName += "/AudioRecordTest_" + tsLong.toString() + ".mp3";

How to solve this warning message. Feel free to modify the code if there is any other mistake.

Answer 1

Correct me if I'm wrong, but I expect that the (compilation) warning message really says this:

Result of File.mkdir() is ignored

... or something like that. It is telling you that you are ignoring the result of the mkdir() call that tells you whether or not a directory was created.

One way to avoid the warning would be to test the result and act appropriately. Another would be to simply assign the result to a temporary variable, ignore it, and (potentially) crash later because the directory wasn't created when it should have been.

(Guess which solution is better ...)

---

Feel free to modify the code if there is any other mistake.

Since you asked ... it is BAD STYLE to use Hungarian notation for Java variable names. Java is a strongly typed language where all variables have a clear declared types. You should not need the mental crutches of some ghastly identifier convention to tell you what a variable's type is intended to be.

Answer 2

As @Stephen C suggests, i handled in these ways

1)

boolean isDirectoryCreated= path.mkdir();

and ignore 'isDirectoryCreated'

2) (Recommended)

 boolean isDirectoryCreated=path.exists();
 if (!isDirectoryCreated) {
     isDirectoryCreated= path.mkdir();
 }
 if(isDirectoryCreated) {
    // do something
 }

3)

if (!path.exists()) {
   if(path.mkdir()){
     // do something
   }
}

Answer 3

If you want to ignore this warning, add this on the method: @SuppressWarnings("all")

Answer 4

I created a utility function:

@SuppressWarnings("unused")
private static void IGNORE_RESULT(boolean b) {}

And then to use:

IGNORE_RESULT(path.mkdir());

I like this solution because it is self documenting. You are explicitly stating that you know there is a result and you are intentionally ignoring it. It should also optimize out to a NOP during compilation so there is no unnecessary test at runtime just to suppress a useless warning.