Strings (Apache Log4j API 2.17.1 API)

java.lang.Object
- org.apache.logging.log4j.util.Strings

```
public final class Strings
extends Object
```
Consider this class private.

See Also:

Apache Commons Lang

Field Summary

Fields
Modifier and Type	Field and Description
`static String`	`EMPTY` The empty string.
`static String[]`	`EMPTY_ARRAY` The empty array.
`static String`	`LINE_SEPARATOR` OS-dependent line separator, defaults to `"\n"` if the system property `""line.separator"` cannot be read.

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static String`	`concat(String str1, String str2)` Concatenates 2 Strings without allocation.
`static String`	`dquote(String str)` Returns a double quoted string.
`static boolean`	`isBlank(String s)` Checks if a String is blank.
`static boolean`	`isEmpty(CharSequence cs)` Checks if a CharSequence is empty ("") or null.
`static boolean`	`isNotBlank(String s)` Checks if a String is not blank.
`static boolean`	`isNotEmpty(CharSequence cs)` Checks if a CharSequence is not empty ("") and not null.
`static String`	`join(Iterable<?> iterable, char separator)` Joins the elements of the provided `Iterable` into a single String containing the provided elements.
`static String`	`join(Iterator<?> iterator, char separator)` Joins the elements of the provided `Iterator` into a single String containing the provided elements.
`static String`	`left(String str, int len)` Gets the leftmost `len` characters of a String.
`static String`	`quote(String str)` Returns a quoted string.
`static String`	`repeat(String str, int count)` Creates a new string repeating given `str` `count` times.
`static String`	`toRootUpperCase(String str)` Shorthand for `str.toUpperCase(Locale.ROOT);`
`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`.

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

- Field Detail
  - EMPTY
```
public static final String EMPTY
```
    The empty string.
    
    See Also:
    
    Constant Field Values
  - 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 Detail
  - 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 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
  - 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
  - toRootUpperCase
```
public static String toRootUpperCase(String str)
```
    Shorthand for str.toUpperCase(Locale.ROOT);
    
    Parameters:
    
    str - The string to upper case.
    
    Returns:
    
    a new string
    
    See Also:
    
    String.toLowerCase(Locale)
  - 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

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Class Strings

Field Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

EMPTY

EMPTY_ARRAY

LINE_SEPARATOR

Method Detail

dquote

isBlank

isEmpty

isNotBlank

isNotEmpty

join

join

left

quote

trimToNull

toRootUpperCase

concat

repeat