Regex can also be good and be used effectively (Replaces all UTF-8 characters not covered in ISO-8859-1
with space):
String input = "€Tes¶ti©ng [§] al€l o€f i¶t _ - À ÆÑ with some 9umbers as"
+ " w2921**#$%!@# well Ü, or ü, is a chaŒracte?";
String output = input.replaceAll("[^\\u0020-\\u007e\\u00a0-\\u00ff]", " ");
System.out.println("Input = " + input);
System.out.println("Output = " + output);