Setting the default Java character encoding

How do I properly set the default character encoding used by the JVM (1.5.x) programmatically?

I have read that -Dfile.encoding=whatever used to be the way to go for older JVMs. I don't have that luxury for reasons I wont get into.

I have tried:

System.setProperty("file.encoding", "UTF-8");

And the property gets set, but it doesn't seem to cause the final getBytes call below to use UTF8:

System.setProperty("file.encoding", "UTF-8");

byte inbytes[] = new byte[1024];

FileInputStream fis = new FileInputStream("response.txt");
fis.read(inbytes);
FileOutputStream fos = new FileOutputStream("response-2.txt");
String in = new String(inbytes, "UTF8");
fos.write(in.getBytes());

Solution 1:

Unfortunately, the file.encoding property has to be specified as the JVM starts up; by the time your main method is entered, the character encoding used by String.getBytes() and the default constructors of InputStreamReader and OutputStreamWriter has been permanently cached.

As Edward Grech points out, in a special case like this, the environment variable JAVA_TOOL_OPTIONS can be used to specify this property, but it's normally done like this:

java -Dfile.encoding=UTF-8 … com.x.Main

Charset.defaultCharset() will reflect changes to the file.encoding property, but most of the code in the core Java libraries that need to determine the default character encoding do not use this mechanism.

When you are encoding or decoding, you can query the file.encoding property or Charset.defaultCharset() to find the current default encoding, and use the appropriate method or constructor overload to specify it.

Solution 2:

From the JVM™ Tool Interface documentation…

Since the command-line cannot always be accessed or modified, for example in embedded VMs or simply VMs launched deep within scripts, a JAVA_TOOL_OPTIONS variable is provided so that agents may be launched in these cases.

By setting the (Windows) environment variable JAVA_TOOL_OPTIONS to -Dfile.encoding=UTF8, the (Java) System property will be set automatically every time a JVM is started. You will know that the parameter has been picked up because the following message will be posted to System.err:

Picked up JAVA_TOOL_OPTIONS: -Dfile.encoding=UTF8

Solution 3:

I have a hacky way that definitely works!!

System.setProperty("file.encoding","UTF-8");
Field charset = Charset.class.getDeclaredField("defaultCharset");
charset.setAccessible(true);
charset.set(null,null);

This way you are going to trick JVM which would think that charset is not set and make it to set it again to UTF-8, on runtime!

Solution 4:

I think a better approach than setting the platform's default character set, especially as you seem to have restrictions on affecting the application deployment, let alone the platform, is to call the much safer String.getBytes("charsetName"). That way your application is not dependent on things beyond its control.

I personally feel that String.getBytes() should be deprecated, as it has caused serious problems in a number of cases I have seen, where the developer did not account for the default charset possibly changing.

Solution 5:

I can't answer your original question but I would like to offer you some advice -- don't depend on the JVM's default encoding. It's always best to explicitly specify the desired encoding (i.e. "UTF-8") in your code. That way, you know it will work even across different systems and JVM configurations.