FindBug: Solving DM_DEFAULT_ENCODING Warning When Using FileWriter

PROBLEM

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.

SOLUTION

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();

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