import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CharacterCodingException;

public class StringUtils {
  private StringUtils() {}

  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;
  }

  public static void main (String args[]) throws Exception {
    String test = "Réal";
    System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));
    test = "Real";
    System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));
    /*
     * output :
     *   Réal isPureAscii() : false
     *   Real isPureAscii() : true
     */
  }
}

import java.nio.charset.Charset;

public class StringUtils {

  public static boolean isPureAscii(String v) {
    return Charset.forName("US-ASCII").newEncoder().canEncode(v);
    // or "ISO-8859-1" for ISO Latin 1
    // or StandardCharsets.US_ASCII with JDK1.7+
  }

  public static void main (String args[]) throws Exception {
    String test = "Réal";
    System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));
    test = "Real";
    System.out.println(test + " isPureAscii() : " + StringUtils.isPureAscii(test));

     /*
      * output :
      *   Réal isPureAscii() : false
      *   Real isPureAscii() : true
      */
  }
}

public class Test {
  public static void main(String args[]){
    String input = "eéaà";
    String output = input.replaceAll("[^\\p{ASCII}]", "");
    System.out.println(output);
    /*
     * output : ea
     */
  }
}