[java] How to check if a folder exists

Generate a file from the string of your folder directory

String path="Folder directory";    
File file = new File(path);

and use method exist.
If you want to generate the folder you sould use mkdir()

if (!file.exists()) {
            System.out.print("No Folder");
            file.mkdir();
            System.out.print("Folder created");
        }