This section provides a tutorial example on how to enter Unicode characters using \uxxxx escape sequences in a Java program, and same them to any giving character set encoding.
Encoding conversion is about reading strings of characters stored in a file encoded with
encoding A, and writing them into another file encoded with encoding B.
Before going into details on encoding conversion, let's talk briefly about
Unicode data entry. How do we enter Unicode characters into a file? There are
a couple of ways to do that:
Using encoding specific word processors. Usually, one word processor will
allow you to enter characters of a particular language or encoding.
Using Hex editors to enter directly the byte sequences representing the
desired characters in a specific encoding.
Using Unicode based programming language to enter the desired characters as
string literals.
Word processors are too specific to be discussed here.
Hex editors are ultimate data entry tools for Unicode characters. They can also
be used to inspect and repair encoded text files. But Hex editors are very hard
to use. Note that Notepad on Windows is not a Hex editor. But UltraEdit on Windows is a Hex editor.
Using Unicode based programming language, like Java, to enter Unicode characters into a file
is very interesting. For each character in a string literal, you can use the \uxxxx escape sequence
to represent the character by enter its code value in Hex format.
Here is a sample program, UnicodeHello.java, showing you how to use \uxxxx escape sequences:
/**
* UnicodeHello.java
* Copyright (c) 2002 by Dr. Herong Yang
*
* This program is a simple tool to allow you to enter several lines of
* text, and writh them into a file with of the specified encoding
* (charset name). The input text lines uses Java string convention,
* which allows you to enter ASCII characters directly, and any non
* ASCII characters with escape sequences.
*
* This version of the program is to write out the "Hello world!"
* message in some different languages.
*/
import java.io.*;
class UnicodeHello {
public static void main(String[] a) {
// The following Array contains text to be saved into the output
// File. To enter your own text, just replace this Array.
String[] text = {
"Hello computer! - English", // ASCII
"\u7535\u8111\u4F60\u597D\uFF01 - Simplified Chinese", // GB2312
"\u96FB\u8166\u4F60\u597D\uFE57 - Traditional Chinese" // Big5
};
String outFile = "hello.utf-16be";
if (a.length>0) outFile = a[0];
String outCharsetName = "utf-16be";
if (a.length>1) outCharsetName = a[1];
String crlf = System.getProperty("line.separator");
try {
OutputStreamWriter out = new OutputStreamWriter(
new FileOutputStream(outFile), outCharsetName);
for (int i=0; i<text.length; i++) {
out.write(text[i]);
out.write(crlf);
}
out.close();
} catch (IOException e) {
System.out.println(e.toString());
}
}
}
As you can see from the source code, this program will write the "Hello computer!"
message in several languages. Let's compile this program and run it to get the
characters saved into a file with UTF-16BE encoding:
