Package org.apache.logging.log4j.util

Class Strings

java.lang.Object
org.apache.logging.log4j.util.Strings
@InternalApi public final class Strings extends Object
Consider this class private.
See Also:

  • Field Details

    • EMPTY

      public static final String EMPTY
      The empty string.
      See Also:

    • EMPTY_ARRAY

      public static final String[] EMPTY_ARRAY
      The empty array.

    • LINE_SEPARATOR

      public static final String LINE_SEPARATOR
      OS-dependent line separator, defaults to "\n" if the system property ""line.separator" cannot be read.

  • Method Details

    • dquote

      public static String dquote(String str)
      Returns a double quoted string.
      Parameters:
      str - a String
      Returns:
      "str"

    • isBlank

      public static boolean isBlank(String s)
      Checks if a String is blank. A blank string is one that is either null, empty, or all characters are Character.isWhitespace(char).
      Parameters:
      s - the String to check, may be null
      Returns:
      true if the String is null, empty, or all characters are Character.isWhitespace(char)

    • isEmpty

      public static boolean isEmpty(CharSequence cs)

      Checks if a CharSequence is empty ("") or null. 

       Strings.isEmpty(null)      = true
 Strings.isEmpty("")        = true
 Strings.isEmpty(" ")       = false
 Strings.isEmpty("bob")     = false
 Strings.isEmpty("  bob  ") = false

      NOTE: This method changed in Lang version 2.0. It no longer trims the CharSequence. That functionality is available in isBlank().

      Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isEmpty(CharSequence)

      Parameters:
      cs - the CharSequence to check, may be null
      Returns:
      true if the CharSequence is empty or null

    • isNotBlank

      public static boolean isNotBlank(String s)
      Checks if a String is not blank. The opposite of isBlank(String).
      Parameters:
      s - the String to check, may be null
      Returns:
      true if the String is non-null and has content after being trimmed.

    • isNotEmpty

      public static boolean isNotEmpty(CharSequence cs)

      Checks if a CharSequence is not empty ("") and not null. 

       Strings.isNotEmpty(null)      = false
 Strings.isNotEmpty("")        = false
 Strings.isNotEmpty(" ")       = true
 Strings.isNotEmpty("bob")     = true
 Strings.isNotEmpty("  bob  ") = true

      Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.isNotEmpty(CharSequence)

      Parameters:
      cs - the CharSequence to check, may be null
      Returns:
      true if the CharSequence is not empty and not null

    • join

      public static String join(Iterable<?> iterable, char separator)

      Joins the elements of the provided Iterable into a single String containing the provided elements.

      No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

      Parameters:
      iterable - the Iterable providing the values to join together, may be null
      separator - the separator character to use
      Returns:
      the joined String, null if null iterator input

    • join

      public static String join(Iterator<?> iterator, char separator)

      Joins the elements of the provided Iterator into a single String containing the provided elements.

      No delimiter is added before or after the list. Null objects or empty strings within the iteration are represented by empty strings.

      Parameters:
      iterator - the Iterator of values to join together, may be null
      separator - the separator character to use
      Returns:
      the joined String, null if null iterator input

    • splitList

      public static String[] splitList(String string)

    • left

      public static String left(String str, int len)

      Gets the leftmost len characters of a String.

      If len characters are not available, or the String is null, the String will be returned without an exception. An empty String is returned if len is negative.

       StringUtils.left(null, *)    = null
 StringUtils.left(*, -ve)     = ""
 StringUtils.left("", *)      = ""
 StringUtils.left("abc", 0)   = ""
 StringUtils.left("abc", 2)   = "ab"
 StringUtils.left("abc", 4)   = "abc"

      Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.

      Parameters:
      str - the String to get the leftmost characters from, may be null
      len - the length of the required String
      Returns:
      the leftmost characters, null if null String input

    • quote

      public static String quote(String str)
      Returns a quoted string.
      Parameters:
      str - a String
      Returns:
      'str'

    • trimToNull

      public static String trimToNull(String str)

      Removes control characters (char <= 32) from both ends of this String returning null if the String is empty ("") after the trim or if it is null.

      The String is trimmed using String.trim(). Trim removes start and end characters <= 32. 

       Strings.trimToNull(null)          = null
 Strings.trimToNull("")            = null
 Strings.trimToNull("     ")       = null
 Strings.trimToNull("abc")         = "abc"
 Strings.trimToNull("    abc    ") = "abc"

      Copied from Apache Commons Lang org.apache.commons.lang3.StringUtils.trimToNull(String)

      Parameters:
      str - the String to be trimmed, may be null
      Returns:
      the trimmed String, null if only chars <= 32, empty or null String input

    • toRootLowerCase

      public static String toRootLowerCase(String str)
      Shorthand for str.toLowerCase(Locale.ROOT);
      Parameters:
      str - The string to upper case.
      Returns:
      a new string
      See Also:

    • toRootUpperCase

      public static String toRootUpperCase(String str)
      Shorthand for str.toUpperCase(Locale.ROOT);
      Parameters:
      str - The string to lower case.
      Returns:
      a new string
      See Also:

    • concat

      public static String concat(String str1, String str2)
      Concatenates 2 Strings without allocation.
      Parameters:
      str1 - the first string.
      str2 - the second string.
      Returns:
      the concatenated String.

    • repeat

      public static String repeat(String str, int count)
      Creates a new string repeating given str count times.
      Parameters:
      str - input string
      count - the repetition count
      Returns:
      the new string
      Throws:
      IllegalArgumentException - if either str is null or count is negative