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If a byte array contains non-Unicode text, you can convert the text to Unicode with one of theString
constructor methods. Conversely, you can convert aString
object into a byte array of non-Unicode characters with theString.getBytes
method. When invoking either of these methods, you specify the encoding identifier as one of the parameters.The example that follows converts characters between UTF-8 and Unicode. UTF-8 is a transmission format for Unicode that is safe for UNIX file systems. The full source code for the example is in the file
StringConverter.java
.
The
StringConverter
program starts by creating aString
containing Unicode characters:String original = new String("A" + "\u00ea" + "\u00f1" + "\u00fc" + "C");When printed, the
String
namedoriginal
appears as:AêñüCTo convert the
String
object to UTF-8, invoke thegetBytes
method and specify the appropriate encoding identifier as a parameter. ThegetBytes
method returns an array of bytes in UTF-8 format. To create aString
object from an array of non-Unicode bytes, invoke theString
constructor with the encoding parameter. The code that makes these calls is enclosed in atry
block, in case the specified encoding is unsupported:try { byte[] utf8Bytes = original.getBytes("UTF8"); byte[] defaultBytes = original.getBytes(); String roundTrip = new String(utf8Bytes, "UTF8"); System.out.println("roundTrip = " + roundTrip); System.out.println(); printBytes(utf8Bytes, "utf8Bytes"); System.out.println(); printBytes(defaultBytes, "defaultBytes"); } catch (UnsupportedEncodingException e) { e.printStackTrace(); }The
StringConverter
program prints out the values in theutf8Bytes
anddefaultBytes
arrays to demonstrate an important point: The length of the converted text might not be the same as the length of the source text. Some Unicode characters translate into single bytes, others into pairs or triplets of bytes.The
printBytes
method displays the byte arrays by invoking thebyteToHex
method, which is defined in the source file,UnicodeFormatter.java
. Here is the
printBytes
method:public static void printBytes(byte[] array, String name) { for (int k = 0; k < array.length; k++) { System.out.println(name + "[" + k + "] = " + "0x" + UnicodeFormatter.byteToHex(array[k])); } }The output of the
printBytes
method follows. Note that only the first and last bytes, the A and C characters, are the same in both arrays:utf8Bytes[0] = 0x41 utf8Bytes[1] = 0xc3 utf8Bytes[2] = 0xaa utf8Bytes[3] = 0xc3 utf8Bytes[4] = 0xb1 utf8Bytes[5] = 0xc3 utf8Bytes[6] = 0xbc utf8Bytes[7] = 0x43 defaultBytes[0] = 0x41 defaultBytes[1] = 0xea defaultBytes[2] = 0xf1 defaultBytes[3] = 0xfc defaultBytes[4] = 0x43
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