EncodingSampler.java - Testing encode() Methods

This section provides a tutorial example on how to use 4 different methods provided in Java to encode characters with a given character encoding.

Java offers 4 methods to perform character encoding:

Here is a program that demonstrate how to encode characters with each of above 4 methods:

/**
 * EncodingSampler2.java
 - Copyright (c) 2012, HerongYang.com, All Rights Reserved.
 */
import java.io.*;
import java.nio.*;
import java.nio.charset.*;
class EncodingSampler2 {
   static String dfltCharset = null;
   static int[] chars={0x0000, 0x003F, 0x0040, 0x007F, 0x0080, 0x00BF,
                        0x00C0, 0x00FF, 0x0100, 0x3FFF, 0x4000, 0x7FFF,
                        0x8000, 0xBFFF, 0xC000, 0xEFFF, 0xF000, 0xFFFF,
                        0x1F108, 0x1F132, 0x1F1A0};
   static char hexDigit[] = {'0', '1', '2', '3', '4', '5', '6', '7',
                             '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'};
   public static void main(String[] arg) {
      String charset = null;
      if (arg.length>0) charset = arg[0];
      OutputStreamWriter o = new OutputStreamWriter(
         new ByteArrayOutputStream());
      dfltCharset = o.getEncoding();
      if (charset==null) System.out.println("Default ("+dfltCharset
         +") encoding:");
      else System.out.println(charset+" encoding:");
      System.out.println("Char,    String, Writer, Charset, Encoder");
      for (int i=0; i<chars.length; i++) {
         int c = chars[i];
         byte[] b1 = encodeByString(c,charset);
         byte[] b2 = encodeByWriter(c,charset);
         byte[] b3 = encodeByCharset(c,charset);
         byte[] b4 = encodeByEncoder(c,charset);
         System.out.print(intToHex(c)+",");
         printBytes(b1);
         System.out.print(",");
         printBytes(b2);
         System.out.print(",");
         printBytes(b3);
         System.out.print(",");
         printBytes(b4);
         System.out.println("");
      }
   }
   public static byte[] encodeByCharset(int c, String cs) {
      Charset cso = null;
      byte[] b = null;
      try {   	
         if (cs==null) cso = Charset.forName(dfltCharset);
         else cso = Charset.forName(cs);
         ByteBuffer bb = cso.encode(new String(Character.toChars(c)));
         b = copyBytes(bb.array(),bb.limit());
      } catch (IllegalCharsetNameException e) {
         System.out.println(e.toString());
      }      	
      return b;
   }
   public static byte[] encodeByEncoder(int c, String cs) {
      Charset cso = null;
      byte[] b = null;
      try {   	
         if (cs==null) cso = Charset.forName(dfltCharset);
         else cso = Charset.forName(cs);
         CharsetEncoder e =  cso.newEncoder();
         e.reset();
         ByteBuffer bb 
            = e.encode(CharBuffer.wrap(Character.toChars(c)));
         b = copyBytes(bb.array(),bb.limit());
      } catch (IllegalCharsetNameException e) {
         System.out.println(e.toString());
      } catch (CharacterCodingException e) {
         //System.out.println(e.toString());
         b = new byte[] {(byte)0x00};
      }      	
      return b;
   }
   public static byte[] encodeByString(int c, String cs) {
      String s = new String(Character.toChars(c));
      byte[] b = null;
      if (cs==null) {
         b = s.getBytes();
      } else {
         try {
            b = s.getBytes(cs);
         } catch (UnsupportedEncodingException e) {
            System.out.println(e.toString());
         }
      }
      return b;
   }
   public static byte[] encodeByWriter(int c, String cs) {
      byte[] b = null;
      ByteArrayOutputStream bs = new ByteArrayOutputStream();
      OutputStreamWriter o = null;
      if (cs==null) {
         o = new OutputStreamWriter(bs);
      } else {
         try {
            o = new OutputStreamWriter(bs, cs);
         } catch (UnsupportedEncodingException e) {
            System.out.println(e.toString());
         }
      }
      String s = new String(Character.toChars(c));
      try {
         o.write(s);
         o.flush();
         b = bs.toByteArray();
         o.close();
      } catch (IOException e) {
         System.out.println(e.toString());
      }
      return b;
   }
   public static byte[] copyBytes(byte[] a, int l) {
      byte[] b = new byte[l];
      for (int i=0; i<Math.min(l,a.length); i++) b[i] = a[i];
      return b;
   }
   public static void printBytes(byte[] b) {
      for (int j=0; j<b.length; j++)
         System.out.print(" "+byteToHex(b[j]));
   }
   public static String byteToHex(byte b) {
      char[] a = { hexDigit[(b >> 4) & 0x0f], hexDigit[b & 0x0f] };
      return new String(a);
   }
   public static String charToHex(char c) {
      byte hi = (byte) (c >>> 8);
      byte lo = (byte) (c & 0xff);
      return byteToHex(hi) + byteToHex(lo);
   }
   public static String intToHex(int i) {
      char hi = (char) (i >>> 16);
      char lo = (char) (i & 0xffff);
      return charToHex(hi) + charToHex(lo);
   }
}

Note that:

Last update: 2012.

Table of Contents

 About This Book

 Character Sets and Encodings

 ASCII Character Set and Encoding

 GB2312 Character Set and Encoding

 GB18030 Character Set and Encoding

 JIS X0208 Character Set and Encodings

 Unicode Character Set

 UTF-8 (Unicode Transformation Format - 8-Bit)

 UTF-16, UTF-16BE and UTF-16LE Encodings

 UTF-32, UTF-32BE and UTF-32LE Encodings

 Java Language and Unicode Characters

Character Encoding in Java

 What Is Character Encoding?

 List of Supported Character Encodings in Java

EncodingSampler.java - Testing encode() Methods

 Examples of CP1252 and ISO-8859-1 Encodings

 Examples of US-ASCII, UTF-8, UTF-16 and UTF-32 Encodings

 Examples of GB18030 Encoding

 Testing decode() Methods

 Character Set Encoding Maps

 Encoding Conversion Programs for Encoded Text Files

 Using Notepad as a Unicode Text Editor

 Using Microsoft Word as a Unicode Text Editor

 Using Microsoft Excel as a Unicode Text Editor

 Unicode Fonts

 Unicode Code Point Blocks - Code Charts

 Outdated Tutorials

 References

 PDF Printing Version