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javawindowsmacosarrays
Howard
Howard

Reputation: 41

java byte array convert to String, but different result in different os

I have a problem about byte array convert to String as below code:

public static void main(String[] args) {

        System.out.println("--->" + new String(new byte[5]) + "<---");
}

In windows os result: 

--->    <---

In mac os result:

--->��������������������<---

Why? Does everybody has the problem? Help...

Upvotes: 0

Views: 1088

Answers (2)

Adriaan Koster
Adriaan Koster

Reputation: 16209

When you create a String from a byte array, the byte values (0-255) are converted into UTF-16 characters (see the javadoc of java.lang.String). How this conversion is done depends on how the byte values are interpreted. For example: Multiple bytes can make up a single character in the String. If you don't specify the character encoding to use, the default encoding is used. This can differ between platforms. See this Oracle tutorial about byte encodings and Strings.

To create a String using UTF-8 (a common choice for Java applications), you can do this:

byte[] bytes = new byte[5];
// TODO: fill array with values
String utf8 = new String(bytes, java.nio.charset.StandardCharsets.UTF_8);

(using java.nio.charset.StandardCharsets which is available since Java 7)

Upvotes: 2

Peter Lawrey
Peter Lawrey

Reputation: 533720

You are using a byte array which is full of \0 nul bytes.

How this is translated into a character depends on the character encoding you are using. In your case, you haven't specified the character encoding so it is what ever is the default on your OS, which you can expect will be different on different OSes.

The simple answers is, don't leave this to chance and specify the character encoding you want.

 System.out.println("--->" + new String(new byte[5], "UTF-8") + "<---");

Note: you have another issue that the fonts will be different on different machines, but you can't control the console font from within a Java program.

Upvotes: 7

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