Java tutorial
//package com.java2s; import java.nio.ByteBuffer; import java.nio.CharBuffer; import java.nio.charset.CharacterCodingException; import java.nio.charset.Charset; import java.nio.charset.CharsetDecoder; public class Main { public static boolean isPureAscii(String v) { byte bytearray[] = v.getBytes(); CharsetDecoder d = Charset.forName("US-ASCII").newDecoder(); try { CharBuffer r = d.decode(ByteBuffer.wrap(bytearray)); r.toString(); } catch (CharacterCodingException e) { return false; } return true; } }