Let’s assume we have the following code to write some data into a file:-
File file = new File(someFilePath); Writer w = new FileWriter(file); PrintWriter pw = new PrintWriter(w); pw.println(someContent); pw.close();
When running this code against a static code analysis tool, such as Findbugs, we get this high priority warning:-
Found reliance on default encoding in com.choonchernlim.epicapp.CodeGeneratorService.createFile(String): new java.io.FileWriter(File) Found a call to a method which will perform a byte to String (or String to byte) conversion, and will assume that the default platform encoding is suitable. This will cause the application behaviour to vary between platforms. Use an alternative API and specify a charset name or Charset object explicitly.
The Javadoc for FileWriter says:-
Convenience class for writing character files. The constructors of this class assume that the default character encoding and the default byte-buffer size are acceptable. To specify these values yourself, construct an OutputStreamWriter on a FileOutputStream.
Obviously, this class is too convenient and FindBugs is not happy about it. Further, there is no way to set a charset using FileWriter.
To make FindBugs as happy as Pharrell Williams, we can use OutputStreamWriter instead because it allows us to specify a charset.
File file = new File(someFilePath); Writer w = new OutputStreamWriter(new FileOutputStream(file), "UTF-8"); PrintWriter pw = new PrintWriter(w); pw.println(someContent); pw.close();