Module org.tentackle.common
Package org.tentackle.common

Class StringHelper

  • public final class StringHelper
extends Object
    Some handy methods for strings.
    Author:
    harald

    • Field Detail

      • stringNormalizer

        public static Function<String,​String> stringNormalizer
        The default normalizer used within the application. Defaults to DefaultStringNormalizer.

    • Method Detail

      • setMaxLogCollectionSize

        public static void setMaxLogCollectionSize​(int maxLogCollectionSize)
        Sets the size limit of collections to be logged.
        If an object is logged and it is a collection and the size exceeds maxLogCollectionSize, only the number of items is logged in objectToLoggableString(java.lang.Object) instead of each item.
        Parameters:
        maxLogCollectionSize - the limit

      • getMaxLogCollectionSize

        public static int getMaxLogCollectionSize()
        Gets the size limit of collections to be logged.
        Returns:
        the limit (default is 10)

      • equalsIgnoreCase

        public static boolean equalsIgnoreCase​(String a,
                                       String b)
        Null safe String.equalsIgnoreCase(String).
        Parameters:
        a - first string, may be null
        b - second string, may be null
        Returns:
        true if equal ignoring the case or both are null

      • toUpper

        public static String toUpper​(String str)
        Converts a string to uppercase allowing null values.
        Parameters:
        str - the string
        Returns:
        the uppercase string or null

      • toLower

        public static String toLower​(String str)
        Converts a string to lowercase allowing null values.
        Parameters:
        str - the string
        Returns:
        the lowercase string or null

      • firstToUpper

        public static String firstToUpper​(String str)
        Converts the first character of string to uppercase.
        Parameters:
        str - the string
        Returns:
        the converted string

      • firstToLower

        public static String firstToLower​(String str)
        Converts the first character of string to uppercase.
        Parameters:
        str - the string
        Returns:
        the converted string

      • getPlainClassName

        public static String getPlainClassName​(String className)
        Gets a classname without any optional generics.
        Parameters:
        className - the original classname
        Returns:
        classname without generics

      • getContinuedLine

        public static String getContinuedLine​(String line)
        Checks whether given string introduces a continuation line.

        This is the case if the last character is an unquoted backslash.

        Parameters:
        line - the source line
        Returns:
        null if line does not introduce a continuation line

      • indexAnyOf

        public static int indexAnyOf​(String str,
                             String anyOf)
        Returns the first index of any of the given characters.
        Parameters:
        str - the string
        anyOf - the characters
        Returns:
        the index to the first character found, -1 if no such character

      • toDoubleQuotes

        public static String toDoubleQuotes​(String str)
        Takes a string, surrounds it with double-quotes and escapes all double-quotes already in the string according to Unix rules. Example: 
         Length 5" --> "Length 5\""
        Parameters:
        str - the string
        Returns:
        the string in double quotes

      • parseString

        public static String parseString​(String str)
        Parses a string.
        The string may be enclosed in double- or single quotes which will be removed. Those special characters may be escaped by a backslash. The backslash itself can be written as a double backslash. Special escapes are:

        \n = new line \r = carriage return \t = tab \f = form feed

        Parameters:
        str - the source string
        Returns:
        a string, never null

      • toParsableString

        public static String toParsableString​(String str)
        Converts a string to a string parsable by parseString(java.lang.String).
        Parameters:
        str - the string
        Returns:
        the parsable string

      • split

        public static List<String> split​(String str,
                                 String delimiters)
        Splits a string keeping strings together.
        The strings may be enclosed in double- or single quotes which will not be removed. Those special characters may be escaped by a backslash. The backslash itself can be written as a double backslash. Special escapes are:

        \n = new line \r = carriage return \t = tab \f = form feed

        Parameters:
        str - the string
        delimiters - the delimiter characters
        Returns:
        the strings, never null

      • isFQCN

        public static boolean isFQCN​(String className)
        Checks whether given string is a fully qualified classname (FQCN).
        The class must belong to a package!
        Parameters:
        className - the classname
        Returns:
        true if FQCN

      • isValidJavaClassName

        public static boolean isValidJavaClassName​(String className)
        Checks that given string is a valid Java classname.
        Both classnames with a full classpath or without are validated.
        Parameters:
        className - the classname
        Returns:
        true if valid

      • isValidJavaPackageName

        public static boolean isValidJavaPackageName​(String packageName)
        Checks that given string is a valid Java packagename.
        This is very restrictive verification. Packagenames must be all lowercase alphabetic or digits and must contain only dots and underscores.
        Parameters:
        packageName - the packagename
        Returns:
        true if valid

      • isValidJavaIdentifier

        public static boolean isValidJavaIdentifier​(String str)
        Returns whether the given string is a valid java identifier.
        Parameters:
        str - the string
        Returns:
        true if valid, false if not

      • readTextFromResource

        public static String readTextFromResource​(Class<?> caller,
                                          String resourceName)
                                   throws IOException
        Reads a textfile from a resource.

        Example: 

           String model = StringHelper.readTextFromResource("/org/tentackle/model/TestModel.txt");
        Parameters:
        caller - the caller class, null to determine via Stackwalker
        resourceName - the name of the resource
        Returns:
        the loaded text
        Throws:
        IOException - if loading failed
        FileNotFoundException - if no such resource found

      • isAllWhitespace

        public static boolean isAllWhitespace​(String str)
        Checks if string contains only whitespaces.
        Parameters:
        str - the string to check
        Returns:
        true if null, empty or all whitespace, false if at least one non-whitespace-character found

      • isReservedWord

        public static boolean isReservedWord​(String word)
        Returns whether given string is a reserved java keyword.
        Parameters:
        word - the string to test
        Returns:
        true if java reserved word

      • digitToString

        public static String digitToString​(Character digit)
        Gets the word-string for a digit.
        Example: 
         '0' --> "zero"
        Parameters:
        digit - the digit character
        Returns:
        the word-string

      • unDiacrit

        public static String unDiacrit​(String str,
                               boolean keepLength)
        Converts special unicode characters (so-called diacrits) to standard ascii.
        Supports also special german and northern european "umlauts".
        Parameters:
        str - the string to be converted
        keepLength - true if the length should be kept, i.e. no Ä to AE, but to A
        Returns:
        the converted string

      • normalize

        public static String normalize​(String str,
                               Function<String,​String> normalizer)
        Normalizes a string (phonetically) for use as PDO.normText.
        Parameters:
        str - the string to be normalized
        normalizer - the normalizer to use, null = global default
        Returns:
        the normalized string

      • normalize

        public static String normalize​(String str)
        Normalizes a string (phonetically) for use as PDO.normText using stringNormalizer.
        Parameters:
        str - the string to be normalized
        Returns:
        the normalized string

      • stripEnclosingDoubleQuotes

        public static String stripEnclosingDoubleQuotes​(String str)
        Strips enclosing double quotes.
        Parameters:
        str - the original string
        Returns:
        the string with its double quotes removed

      • toFixedLength

        public static String toFixedLength​(String str,
                                   int length,
                                   char filler)
        Takes a string and returns one with a given length, cutting or filling up with fillchars, whatever appropriate.
        Parameters:
        str - the string
        length - the length of the returned string
        filler - the character to fill up if str is too short
        Returns:
        the string with the desired length

      • toFixedLength

        public static String toFixedLength​(String str,
                                   int length)
        Takes a string and returns one with a given length, cutting or filling up with spaces, whatever appropriate.
        Parameters:
        str - the string
        length - the length of the returned string
        Returns:
        the string with the desired length

      • toFixedLengthLeftFill

        public static String toFixedLengthLeftFill​(String str,
                                           int length,
                                           char filler)
        Takes a string and returns one with a given length, cutting or filling up with fillchars from the left, whatever appropriate.
        Parameters:
        str - the string
        length - the length of the returned string
        filler - the character to fill up if str is too short
        Returns:
        the string with the desired length

      • toFixedLengthLeftFill

        public static String toFixedLengthLeftFill​(String str,
                                           int length)
        Takes a string and returns one with a given length, cutting or filling up with spaces from the left, whatever appropriate.
        Parameters:
        str - the string
        length - the length of the returned string
        Returns:
        the string with the desired length

      • toDTA

        public static String toDTA​(String str)
        Filters illegal chars for DTA-Files (German "DATENAUSTAUSCH" banking format).
        Parameters:
        str - the string
        Returns:
        the DTA conform string

      • toVarName

        public static String toVarName​(String str)
        Filters illegal chars for Java variable names.
        Parameters:
        str - the string
        Returns:
        the java conform string

      • toCamelCase

        public static String toCamelCase​(String str)
        Converts a dotted path to camelCase.
        Example:
        "alpha.beta.gamma" is converted to "alphaBetaGamma".
        Parameters:
        str - the dotted path
        Returns:
        the camel case path

      • camelCaseToDelimited

        public static String camelCaseToDelimited​(String str,
                                          String delimiter)
        Converts a camelCase string to strings with delimiters.

        Example:
        "alphaBetaGamma" is converted to "alpha.beta.gamma", with delimiter ".".

        Parameters:
        str - the camelcase string
        delimiter - the delimter to insert between parts, null or empty if none
        Returns:
        the converted string

      • isAllDigits

        public static boolean isAllDigits​(String str,
                                  boolean whitespaceAllowed)
        Checks if a string contains only digits or whitespaces, i.e. no illegal char in a number string.
        Parameters:
        str - the string to check
        whitespaceAllowed - true if whitespaces are allowed
        Returns:
        true if no illegal char detected, false otherwise

      • isAllDigits

        public static boolean isAllDigits​(String str)
        checks if a string contains only digits, i.e. no non-number char in string, even no whitespace.
        Parameters:
        str - the string to check
        Returns:
        true if no illegal char detected, false otherwise

      • trim

        public static String trim​(String s,
                          int max)
        Trims a string. The method is nullpointer safe.
        Parameters:
        s - the string, may be null
        max - the maximum number of characters, 0 = minimum length
        Returns:
        the trimmed string, null if s == null

      • trim

        public static String trim​(String s)
        Trims a string. The method is nullpointer safe.
        Parameters:
        s - the string, may be null
        Returns:
        the trimmed string, null if s == null
        See Also:
        trim(java.lang.String, int)

      • trimRight

        public static String trimRight​(String str,
                               char filler)
        Cuts trailing characters.

        Removes all trailing characters of given value from the string. If the string consists of those characters only, the returned string will empty.

        Parameters:
        str - the string
        filler - the filler to remove
        Returns:
        the trimmed string, never null

      • trimLeft

        public static String trimLeft​(String str,
                              char filler)
        Cuts leading characters.

        Removes all leading characters of given value from the string. If the string consists of those characters only, the returned string will be empty.

        Parameters:
        str - the string
        filler - the filler to remove
        Returns:
        the trimmed string, never null

      • fillLeft

        public static String fillLeft​(String str,
                              int length,
                              char filler)
        Fills up a string from the left with a filler character to match a given length.
        If the string is already longer, nothing happens.
        Parameters:
        str - the string
        length - the desired length
        filler - the filler character
        Returns:
        the filled string, never null

      • fillRight

        public static String fillRight​(String str,
                               int length,
                               char filler)
        Fills up a string to the right with a filler character to match a given length.
        If the string is already longer, nothing happens.
        Parameters:
        str - the string
        length - the desired length
        filler - the filler character
        Returns:
        the filled string, never null

      • firstBefore

        public static String firstBefore​(String str,
                                 char delimiter)
        Gets the part of a string before a given delimiter.
        Parameters:
        str - the string
        delimiter - the delimiter
        Returns:
        the first part up to but excluding delimiter or the string if no delimiter at all

      • lastAfter

        public static String lastAfter​(String str,
                               char delimiter)
        Gets the part of a string after a given delimiter.
        Parameters:
        str - the string
        delimiter - the delimiter
        Returns:
        the last part following delimiter or the string if no delimiter at all

      • firstLine

        public static String firstLine​(String str)
        Gets the first line from a multi-line string. Nice in tables.
        Parameters:
        str - the multiline string
        Returns:
        the first line, null if str == null

      • toHexString

        public static String toHexString​(byte[] binaryData)
        Creates a human-readable hex-String out of a byte-array (e.g. from MessageDigest MD5sum).
        Parameters:
        binaryData - the data, may be null
        Returns:
        the formatted hex string , null if data was null

      • toBytes

        public static byte[] toBytes​(char c)
        Converts a single (unicode) char to a byte-array.
        Parameters:
        c - the character
        Returns:
        the byte[2] array

      • toBytes

        public static byte[] toBytes​(char[] chars)
        Converts a char-array to a byte-array.
        Parameters:
        chars - the character array
        Returns:
        the byte array, empty if chars is null

      • hash

        public static String hash​(String algorithm,
                          char[] salt,
                          char[] input)
        Builds a hash from an array of chars.
        Note that this method converts the characters to bytes via toBytes(char[]) before applying the hash.
        Parameters:
        algorithm - the hashing algorithm (MD5, SHA-1, SHA-256 are supported by all java runtimes, at least)
        salt - the "salt", null if plain hash
        input - is the input array of chars
        Returns:
        the hash as a string, null if input == null

      • objectToLoggableString

        public static String objectToLoggableString​(Object object)
        Converts a value to a loggable string.
        Parameters:
        object - the object
        Returns:
        the string

      • countOccurrences

        public static int countOccurrences​(String str,
                                   char c)
        Counts the number of occurrences of a given character in a string.
        Parameters:
        str - the string to test
        c - the character to check for
        Returns:
        the number of times c is part of str

      • objectArrayToString

        public static String objectArrayToString​(Object[] objArray,
                                         String separator)
        Creates a string from an object array.
        Parameters:
        objArray - the array of objects
        separator - the string between two objects
        Returns:
        the string

      • toCharArray

        public static char[] toCharArray​(String str)
        Null-safe string to a char-array conversion.
        Parameters:
        str - the string, may be null
        Returns:
        the character array, null if str was null
        See Also:
        String.toCharArray()

      • fill

        public static void fill​(char[] buf,
                        char val)
        Null-safe char array filler.
        Parameters:
        buf - the char buffer, may be null
        val - the value to fill
        See Also:
        Arrays.fill(char[], char)

      • blank

        public static void blank​(char[] buf)
        Null-safe char array filler.
        Fills with blanks.
        Parameters:
        buf - the char buff, may be null
        See Also:
        fill(char[], char)

      • toHTML

        public static String toHTML​(String text)
        Converts a multiline string to an HTML-string that can be displayed in a label. Useful to print multiline labels.
        Parameters:
        text - the input string
        Returns:
        the HTML string

      • removeTrailingText

        public static String removeTrailingText​(String str,
                                        String... trail)
        Removes a trailing text from a string.
        Stops when the first trailing string is found.
        Parameters:
        str - the original string
        trail - the trailing string(s) to remove
        Returns:
        the shortened text, str if nothing removed

      • toAsciiLetterOrDigit

        public static String toAsciiLetterOrDigit​(String str)
        Converts to string containing only the letters A-z or digits.
        All other characters will be converted to an underscore. All diacrits will be converted first (see unDiacrit(java.lang.String, boolean). The resulting string will not contain more than one underscore in a row.

        Nice to create filenames.

        Parameters:
        str - the string
        Returns:
        the filename

      • getPlatform

        public static String getPlatform()
        Gets the name of the operating system from the system properties.
        Returns:
        the normalized platform name

      • getArchitecture

        public static String getArchitecture()
        Gets the name of the architecture from the system properties.
        Returns:
        the normalized architecture name

      • filterUpperCase

        public static String filterUpperCase​(String str)
        Gets the uppercase letters only.
        Useful to get the camel case letters of a string.
        Parameters:
        str - the string
        Returns:
        the upper case letters

      • evaluate

        public static String evaluate​(String str,
                              Function<String,​String> variableProvider)
        Evaluates a string replacing variables.
        The semantics are very much the same as known from the maven resources plugin, but with the extension of optional default values and that @ turns off nested variable processing.

        Syntax: $|@{name[?|!default]}, where name is the variable name and default is the default value to be used if there is no such variable (!) or variable is empty (@{link isAllWhitespace(String)}) or doesn't exist (?).

        Characters can be quoted with a backslash. A double backslash is treated as a single backslash.

        Examples: 

            @{user.home}/somedir
    @{user.home?/tmp}/somedir
    @{user.home!/tmp}/somedir
        Notice that ${...} may lead to unexpected results, if the variable's value contains backslashes, as with windows pathnames, for example.
        Parameters:
        str - the string
        variableProvider - the variables as properties
        Returns:
        the processed string

      • levenshteinDistance

        public static int levenshteinDistance​(String s1,
                                      String s2)
        Determines the Levenshtein distance of two strings.
        Notice that for s1 and s2 null values are treated as empty strings.
        Parameters:
        s1 - the first string
        s2 - the second string
        Returns:
        the distance