I am beginner and self-learning in Java programming.
So, I want to know about difference between
String.length() is the number of UTF-16 code units needed to represent the string. That is, it is the number of
char values that are used to represent the string (thus equal to
toCharArray().length). For western languages this is typically the same as the number of unicode characters (code points) in the string. The values will different any time UTF-16 surrogate pairs are used. Such pairs are needed only to encode characters outside the BMP and are rarely used in most writing.
String.getBytes().length is the number of bytes needed to represent your string in the platform's default encoding. For example, if the default encoding was UTF-16 (rare), it would be exactly 2x the value returned by
String.length(). More commonly, your platform encoding will be a multi-byte encoding like UTF-8.
This means the relationship between those two lengths are more complex. For ASCII strings, the two calls will almost always produce the same result (outside of unusual default encodings that don't encode the ASCII subset in 1 byte). Outside of ASCII strings,
String.getBytes().length is likely to be longer, as it counts bytes needed to represent the string, while
length() counts 2-byte code units.
Which is more suitable?
Usually you'll use
String.length() in concert with other string methods that take offsets into the string. E.g., to get the last character, you'd use
str.charAt(str.length()-1). You'd only use the
getBytes().length if for some reason you were dealing with the array-of-bytes encoding returned by