What is the default encoding of the JVM?

Question

Is UTF-8 the default encoding in Java?
If not, how can I know which encoding is used by default?

Solution 1

The default character set of the JVM is that of the system it's running on. There's no specific value for this and you shouldn't generally depend on the default encoding being any particular value.

It can be accessed at runtime via Charset.defaultCharset(), if that's any use to you, though really you should make a point of always specifying encoding explicitly when you can do so.

Solution 2

Note that you can change the default encoding of the JVM using the confusingly-named property file.encoding.

If your application is particularly sensitive to encodings (perhaps through usage of APIs implying default encodings), then you should explicitly set this on JVM startup to a consistent (known) value.

Solution 3

There are three "default" encodings:

• file.encoding:
  System.getProperty("file.encoding")

• java.nio.Charset:
  Charset.defaultCharset()

• And the encoding of the InputStreamReader:
  InputStreamReader.getEncoding()

You can read more about it on this page.

Solution 4

To get default java settings just use :

java -XshowSettings 

Solution 5

I am sure that this is JVM implemenation specific, but I was able to "influence" my JVM's default file.encoding by executing:

export LC_ALL=en_US.UTF-8

(running java version 1.7.0_80 on Ubuntu 12.04)

Also, if you type "locale" from your unix console, you should see more info there.

All the credit goes to http://www.philvarner.com/2009/10/24/unicode-in-java-default-charset-part-4/

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Comments

[sleske]

Note that file.encoding must be specified on JVM startup (i.e. as cmdline parameter -Dfile.encoding or via JAVA_TOOLS_OPTIONS); you can set it at runtime, but it will not matter. See stackoverflow.com/questions/361975/…

[Jonas Elfström]

If you are correct I find it a bit strange java.sun.com/javase/technologies/core/basic/intl/… says that it's always UTF-16.

[JesperE]

UTF-16 is how text is represented internally in the JVM. The default encoding determines how the JVM interprets bytes read from files (using FileReader, for example).

[Koray Tugay]

So it depends on the encoding the host operating system has?

[Jeutnarg]

This answer is correct, but for reference, on Linux it's usually "UTF-8", and on Windows it's usually "cp1252".

[Gunslinger]

I have just experienced an linux installation that report UTF-8 from locale, but java says US-ASCII.

[Artem Novikov]

Wrong. Check Charset.defaultCharset() source code. It reads file.encoding property, otherwise uses UTF-8.

[Artem Novikov]

How did you check it? I can't find a proof Java pays any attention to the encoding in the locale string. Only from file.encoding property.

[Jules]

@ArtemNovikov - yes, but what is the default value of file.encoding? It's initialised in java.lang.System.initProperties based on the value of sprops.encoding, where sprops is a structure returned by the native function GetJavaProperties(), the implementation of which varies according to platform. In the Windows version, for example, it calls GetUserDefaultLCID() and then GetLocaleInfo (lcid, LOCALE_IDEFAULTANSICODEPAGE, ...) to find the user's default ANSI code page and uses that. On Unix platforms, it parses the return of setlocale(LC_CTYPE, NULL).

[Jules]

... See hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/shar‌​e/… and hg.openjdk.java.net/jdk8/jdk8/jdk/file/687fd7c7986d/src/sola‌​ris/… for details.

[Rahul]

@JesperE : "text is represented internally in the JVM" : you mean bytecode ?

[JesperE]

@Rahul No, I mean how text is represented in memory in the JVM. Not sure what the bytecode spec says, I was referring to how the JVM stores text in memory at runtime. At least I think so, but my comment was made 6 years ago, so I might misremember.