Creating temporary files in Android

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What's the best way to create a temporary file in Android?

Can File.createTempFile be used? The documentation is very vague about it.

In particular, it's not clear when temporary files created with File.createTempFile are deleted, if ever.

6 Answers

For temporary internal files their are 2 options

1.

File file; 
file = File.createTempFile(filename, null, this.getCacheDir());

2.

File file
file = new File(this.getCacheDir(), filename);

Both options adds files in the applications cache directory and thus can be cleared to make space as required but option 1 will add a random number on the end of the filename to keep files unique. It will also add a file extension which is .tmp by default, but it can be set to anything via the use of the 2nd parameter. The use of the random number means despite specifying a filename it doesn't stay the same as the number is added along with the suffix/file extension (.tmp by default) e.g you specify your filename as internal_file and comes out as internal_file1456345.tmp. Whereas you can specify the extension you can't specify the number that is added. You can however find the filename it generates via file.getName();, but you would need to store it somewhere so you can use it whenever you wanted for example to delete or read the file. Therefore for this reason I prefer the 2nd option as the filename you specify is the filename that is created.

Do it in simple. According to documentation https://developer.android.com/training/data-storage/files

String imageName = "IMG_" + String.valueOf(System.currentTimeMillis()) +".jpg";
        picFile = new File(ProfileActivity.this.getCacheDir(),imageName);

and delete it after usage

picFile.delete()
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