检查字符串是否为合法的Java标识符的程序

class JavaIdentifierTest {

    public static boolean isValidJavaIdentifier( String candidate ) {
        if ( candidate.length( ) == 0 ||
             ! Character.isJavaIdentifierStart( candidate.charAt( 0 ) ) )
            return false;

        String tail = candidate.substring( 1 );
        for ( int i = 0; i < tail.length( ); i++ )
            if ( ! Character.isJavaIdentifierPart( tail.charAt( i ) ) )
                return false;

        return true;
    }