Nov 4, 2012

Removing BOM character from a string in Java

The below code checks if the BOM character is present in a string. If present, removes and prints the string with skipped bom.

import java.io.UnsupportedEncodingException;

/**
 * File: BOM.java
 * 
 * check if the bom character is present in the given string print the string
 * after skipping the utf-8 bom characters print the string as utf-8 string on a
 * utf-8 console
 */

public class BOM
{
    private final static String BOM_STRING = "Hello World";
    private final static String ISO_ENCODING = "ISO-8859-1";
    private final static String UTF8_ENCODING = "UTF-8";
    private final static int UTF8_BOM_LENGTH = 3;

    public static void main(String[] args) throws UnsupportedEncodingException {
        final byte[] bytes = BOM_STRING.getBytes(ISO_ENCODING);
        if (isUTF8(bytes)) {
            printSkippedBomString(bytes);
            printUTF8String(bytes);
        }
    }

    private static void printSkippedBomString(final byte[] bytes) throws UnsupportedEncodingException {
        int length = bytes.length - UTF8_BOM_LENGTH;
        byte[] barray = new byte[length];
        System.arraycopy(bytes, UTF8_BOM_LENGTH, barray, 0, barray.length);
        System.out.println(new String(barray, ISO_ENCODING));
    }

    private static void printUTF8String(final byte[] bytes) throws UnsupportedEncodingException {
        System.out.println(new String(bytes, UTF8_ENCODING));
    }

    private static boolean isUTF8(byte[] bytes) {
        if ((bytes[0] & 0xFF) == 0xEF && 
            (bytes[1] & 0xFF) == 0xBB && 
            (bytes[2] & 0xFF) == 0xBF) {
            return true;
        }
        return false;
    }
}


The following stackoverflow article talks in detail about detecting and skipping the BOM

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