java.lang.Object

tech.tablesaw.util.StringUtils

public class StringUtils extends Object

Operations on String that are null safe.

StringUtils handles null input Strings quietly. That is to say that a null input will return null. Where a boolean or int is being returned details vary by method.

A side effect of the null handling is that a NullPointerException should be considered a bug in StringUtils.

Methods in this class give sample code to explain their operation. The symbol * is used to indicate any input including null.

#ThreadSafe#

Since:

1.0

See Also:

String

Method Summary

Modifier and Type

Method

Description

static String

abbreviate(String str, String abbrevMarker, int maxWidth)

Abbreviates a String using ellipses.

static String

capitalize(String str)

Capitalizes a String changing the first character to title case as per Character.toTitleCase(int).

static boolean

isAllLowerCase(String cs)

Checks if the CharSequence contains only lowercase characters.

static boolean

isAllUpperCase(String cs)

Checks if the CharSequence contains only uppercase characters.

static boolean

isAlpha(String cs)

Checks if the CharSequence contains only Unicode letters.

static boolean

isAlphanumeric(String cs)

Checks if the CharSequence contains only Unicode letters or digits.

static boolean

isNumeric(String cs)

Checks if the CharSequence contains only Unicode digits.

static String

join(Object[] array, char separator)

Joins the elements of the provided array into a single String containing the provided list of elements.

static int

length(CharSequence cs)

Gets a CharSequence length or 0 if the CharSequence is null.

static String

removeZeroDecimal(String str)

Removes all trailing zero decimals from the given String, assuming all decimals are zero and any zero decimals actually exist.

static String

repeat(String str, int repeat)

Repeat a String repeat times to form a new String.

static String[]

splitByCharacterTypeCamelCase(String str)

Splits a String by Character type as returned by java.lang.Character.getType(char).

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details
- splitByCharacterTypeCamelCase
  
  public static String[] splitByCharacterTypeCamelCase(String str)
  
  Splits a String by Character type as returned by java.lang.Character.getType(char). Groups of contiguous characters of the same type are returned as complete tokens, with the following exception: if camelCase is true, the character of type Character.UPPERCASE_LETTER, if any, immediately preceding a token of type Character.LOWERCASE_LETTER will belong to the following token rather than to the preceding, if any, Character.UPPERCASE_LETTER token.
  
  Parameters:
  
  str - the String to split, may be null
  
  Returns:
  
  an array of parsed Strings, null if null String input
  
  Since:
  
  2.4
- join
  
  public static String join(Object[] array, char separator)
  Joins the elements of the provided array into a single String containing the provided list of elements.
  No delimiter is added before or after the list. Null objects or empty strings within the array are represented by empty strings.
  StringUtils.join(null, *) = null StringUtils.join([], *) = "" StringUtils.join([null], *) = "" StringUtils.join(["a", "b", "c"], ';') = "a;b;c" StringUtils.join(["a", "b", "c"], null) = "abc" StringUtils.join([null, "", "a"], ';') = ";;a"
  Parameters:
  
  array - the array of values to join together, may be null
  
  separator - the separator character to use
  
  Returns:
  
  the joined String, null if null array input
  
  Since:
  
  2.0
- repeat
  
  public static String repeat(String str, int repeat)
  Repeat a String repeat times to form a new String.
  StringUtils.repeat(null, 2) = null StringUtils.repeat("", 0) = "" StringUtils.repeat("", 2) = "" StringUtils.repeat("a", 3) = "aaa" StringUtils.repeat("ab", 2) = "abab" StringUtils.repeat("a", -2) = ""
  Parameters:
  
  str - the String to repeat, may be null
  
  repeat - number of times to repeat str, negative treated as zero
  
  Returns:
  
  a new String consisting of the original String repeated, null if null String input
- length
  
  public static int length(CharSequence cs)
  
  Gets a CharSequence length or 0 if the CharSequence is null.
  
  Parameters:
  
  cs - a CharSequence or null
  
  Returns:
  
  CharSequence length or 0 if the CharSequence is null.
  
  Since:
  
  2.4, 3.0 Changed signature from length(String) to length(CharSequence)
- capitalize
  
  public static String capitalize(String str)
  Capitalizes a String changing the first character to title case as per Character.toTitleCase(int). No other characters are changed.
  A null input String returns null.
  StringUtils.capitalize(null) = null StringUtils.capitalize("") = "" StringUtils.capitalize("cat") = "Cat" StringUtils.capitalize("cAt") = "CAt" StringUtils.capitalize("'cat'") = "'cat'"
  Parameters:
  
  str - the String to capitalize, may be null
  
  Returns:
  
  the capitalized String, null if null String input
  
  Since:
  
  2.0
- isAlpha
  
  public static boolean isAlpha(String cs)
  Checks if the CharSequence contains only Unicode letters.
  null will return false. An empty CharSequence (length()=0) will return false.
  StringUtils.isAlpha(null) = false StringUtils.isAlpha("") = false StringUtils.isAlpha(" ") = false StringUtils.isAlpha("abc") = true StringUtils.isAlpha("ab2c") = false StringUtils.isAlpha("ab-c") = false
  Parameters:
  
  cs - the CharSequence to check, may be null
  
  Returns:
  
  true if only contains letters, and is non-null
  
  Since:
  
  3.0 Changed signature from isAlpha(String) to isAlpha(CharSequence), 3.0 Changed "" to return false and not true
- isAlphanumeric
  
  public static boolean isAlphanumeric(String cs)
  Checks if the CharSequence contains only Unicode letters or digits.
  null will return false. An empty CharSequence (length()=0) will return false.
  StringUtils.isAlphanumeric(null) = false StringUtils.isAlphanumeric("") = false StringUtils.isAlphanumeric(" ") = false StringUtils.isAlphanumeric("abc") = true StringUtils.isAlphanumeric("ab c") = false StringUtils.isAlphanumeric("ab2c") = true StringUtils.isAlphanumeric("ab-c") = false
  Parameters:
  
  cs - the CharSequence to check, may be null
  
  Returns:
  
  true if only contains letters or digits, and is non-null
  
  Since:
  
  3.0 Changed signature from isAlphanumeric(String) to isAlphanumeric(CharSequence), 3.0 Changed "" to return false and not true
- isNumeric
  
  public static boolean isNumeric(String cs)
  Checks if the CharSequence contains only Unicode digits. A decimal point is not a Unicode digit and returns false.
  null will return false. An empty CharSequence (length()=0) will return false.
  Note that the method does not allow for a leading sign, either positive or negative. Also, if a String passes the numeric test, it may still generate a NumberFormatException when parsed by Integer.parseInt or Long.parseLong, e.g. if the value is outside the range for int or long respectively.
  StringUtils.isNumeric(null) = false StringUtils.isNumeric("") = false StringUtils.isNumeric(" ") = false StringUtils.isNumeric("123") = true StringUtils.isNumeric("१२३") = true StringUtils.isNumeric("12 3") = false StringUtils.isNumeric("ab2c") = false StringUtils.isNumeric("12-3") = false StringUtils.isNumeric("12.3") = false StringUtils.isNumeric("-123") = false StringUtils.isNumeric("+123") = false
  Parameters:
  
  cs - the CharSequence to check, may be null
  
  Returns:
  
  true if only contains digits, and is non-null
  
  Since:
  
  3.0 Changed signature from isNumeric(String) to isNumeric(CharSequence), 3.0 Changed "" to return false and not true
- isAllLowerCase
  
  public static boolean isAllLowerCase(String cs)
  Checks if the CharSequence contains only lowercase characters.
  null will return false. An empty CharSequence (length()=0) will return false.
  StringUtils.isAllLowerCase(null) = false StringUtils.isAllLowerCase("") = false StringUtils.isAllLowerCase(" ") = false StringUtils.isAllLowerCase("abc") = true StringUtils.isAllLowerCase("abC") = false StringUtils.isAllLowerCase("ab c") = false StringUtils.isAllLowerCase("ab1c") = false StringUtils.isAllLowerCase("ab/c") = false
  Parameters:
  
  cs - the CharSequence to check, may be null
  
  Returns:
  
  true if only contains lowercase characters, and is non-null
  
  Since:
  
  2.5, 3.0 Changed signature from isAllLowerCase(String) to isAllLowerCase(CharSequence)
- isAllUpperCase
  
  public static boolean isAllUpperCase(String cs)
  Checks if the CharSequence contains only uppercase characters.
  null will return false. An empty String (length()=0) will return false.
  StringUtils.isAllUpperCase(null) = false StringUtils.isAllUpperCase("") = false StringUtils.isAllUpperCase(" ") = false StringUtils.isAllUpperCase("ABC") = true StringUtils.isAllUpperCase("aBC") = false StringUtils.isAllUpperCase("A C") = false StringUtils.isAllUpperCase("A1C") = false StringUtils.isAllUpperCase("A/C") = false
  Parameters:
  
  cs - the CharSequence to check, may be null
  
  Returns:
  
  true if only contains uppercase characters, and is non-null
  
  Since:
  
  2.5, 3.0 Changed signature from isAllUpperCase(String) to isAllUpperCase(CharSequence)
- removeZeroDecimal
  
  public static String removeZeroDecimal(String str)
  
  Removes all trailing zero decimals from the given String, assuming all decimals are zero and any zero decimals actually exist.
  A null input String returns null.
  
  Parameters:
  
  str - the String to handle, may be null
  
  Returns:
  
  string without trailing zero decimals
- abbreviate
  
  public static String abbreviate(String str, String abbrevMarker, int maxWidth)
  Abbreviates a String using ellipses. This will turn "Now is the time for all good men" into "Now is the time for..."
  Specifically:
  
  If the number of characters in str is less than or equal to maxWidth, return str.
  Else abbreviate it to (substring(str, 0, max-3) + "...").
  If maxWidth is less than 4, throw an IllegalArgumentException.
  In no case will it return a String of length greater than maxWidth.
  
  StringUtils.abbreviate(null, *) = null StringUtils.abbreviate("", 4) = "" StringUtils.abbreviate("abcdefg", 6) = "abc..." StringUtils.abbreviate("abcdefg", 7) = "abcdefg" StringUtils.abbreviate("abcdefg", 8) = "abcdefg" StringUtils.abbreviate("abcdefg", 4) = "a..." StringUtils.abbreviate("abcdefg", 3) = IllegalArgumentException
  Parameters:
  
  str - the String to check, may be null
  
  abbrevMarker - the String indicate abbreviation
  
  maxWidth - maximum length of result String, must be at least 4
  
  Returns:
  
  abbreviated String, null if null String input
  
  Throws:
  
  IllegalArgumentException - if the width is too small
  
  Since:
  
  2.0

Class StringUtils

Method Summary

Methods inherited from class java.lang.Object

Method Details

splitByCharacterTypeCamelCase

join

repeat

length

capitalize

isAlpha

isAlphanumeric

isNumeric

isAllLowerCase

isAllUpperCase

removeZeroDecimal

abbreviate