removes all unicode characters that are outside the Basic multilingual plane (BMP) - Java java.lang

Java examples for java.lang:String Unicode

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Description

removes all unicode characters that are outside the Basic multilingual plane (BMP)

Demo Code

//package com.java2s;

public class Main {
    public static void main(String[] argv) {
        String str = "java2s.com";
        System.out.println(removeAllNonBMPCharacters(str));
    }//from w w w .  ja v  a2s  . co  m

    /**
     * removes all unicode characters that are outside the Basic multilingual plane (BMP)
     * 
     * @see http://en.wikipedia.org/wiki/Unicode_block
     * 
     * @param str
     * @return
     */
    public static String removeAllNonBMPCharacters(String str) {
        /*
         * java converts utf-8 to utf-16 for internal usage. (http://docs.oracle.com/javase/7/docs/api/java/nio/charset/Charset.html)
         * Thus, there are only 2-byte and 4-byte characters. (http://en.wikipedia.org/wiki/UTF-16)
         * All BMP characters are 2-bytes long, so there are inside of { 0x00, 0x00 } - { 0xFF, 0xFF }
         * So the following regular expression replaces all characters, that do not fit into this range, with an empty string.
         * (don't get confused: ^ inside [] is negation!)
         */
        return str.replaceAll("[^\u0000-\uFFFF]", "");
    }
}

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