JDK Tutorials - Herong's Tutorial Examples - v6.32, by Herong Yang
\uxxxx - Entering Unicode Data in Java Programs
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:
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 Notepad++ 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) HerongYang.com. All Rights Reserved.
*
* This program is a simple tool to allow you to enter several lines of
* text, and write 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:
herong> java UnicodeHello.java hello.utf-16be utf-16be
Now we have a text file with characters saved in UTF-16BE encoding. Read the next section on how to view and inspect this UTF-16BE encoded file.
Table of Contents
Date, Time and Calendar Classes
Date and Time Object and String Conversion
Number Object and Numeric String Conversion
Locales, Localization Methods and Resource Bundles
Calling and Importing Classes Defined in Unnamed Packages
HashSet, Vector, HashMap and Collection Classes
Character Set Encoding Classes and Methods
►Encoding Conversion Programs for Encoded Text Files
►\uxxxx - Entering Unicode Data in Java Programs
HexWriter.java - Converting Encoded Byte Sequences to Hex Values
EncodingConverter.java - Encoding Conversion Sample Program
Viewing Encoded Text Files in Web Browsers
Unicode Signs in Different Encodings
Datagram Network Communication
DOM (Document Object Model) - API for XML Files
DTD (Document Type Definition) - XML Validation
XSD (XML Schema Definition) - XML Validation
XSL (Extensible Stylesheet Language)
Message Digest Algorithm Implementations in JDK
Private key and Public Key Pair Generation
PKCS#8/X.509 Private/Public Encoding Standards
Digital Signature Algorithm and Sample Program
"keytool" Commands and "keystore" Files
KeyStore and Certificate Classes
Secret Key Generation and Management
Cipher - Encryption and Decryption
The SSL (Secure Socket Layer) Protocol
SSL Socket Communication Testing Programs