Package com.google.common.base
Class Strings
java.lang.Object
com.google.common.base.Strings
Static utility methods pertaining to
String
or CharSequence
instances.- Since:
- 3.0
-
Method Summary
Modifier and TypeMethodDescriptionstatic String
Returns the longest stringprefix
such thata.toString().startsWith(prefix) && b.toString().startsWith(prefix)
, taking care not to split surrogate pairs.static String
Returns the longest stringsuffix
such thata.toString().endsWith(suffix) && b.toString().endsWith(suffix)
, taking care not to split surrogate pairs.static String
emptyToNull
(String string) Returns the given string if it is nonempty;null
otherwise.static boolean
isNullOrEmpty
(String string) Returnstrue
if the given string is null or is the empty string.static String
nullToEmpty
(String string) Returns the given string if it is non-null; the empty string otherwise.static String
Returns a string, of length at leastminLength
, consisting ofstring
appended with as many copies ofpadChar
as are necessary to reach that length.static String
Returns a string, of length at leastminLength
, consisting ofstring
prepended with as many copies ofpadChar
as are necessary to reach that length.static String
Returns a string consisting of a specific number of concatenated copies of an input string.
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Method Details
-
nullToEmpty
Returns the given string if it is non-null; the empty string otherwise.- Parameters:
string
- the string to test and possibly return- Returns:
string
itself if it is non-null;""
if it is null
-
emptyToNull
Returns the given string if it is nonempty;null
otherwise.- Parameters:
string
- the string to test and possibly return- Returns:
string
itself if it is nonempty;null
if it is empty or null
-
isNullOrEmpty
Returnstrue
if the given string is null or is the empty string.Consider normalizing your string references with
nullToEmpty(java.lang.String)
. If you do, you can useString.isEmpty()
instead of this method, and you won't need special null-safe forms of methods likeString.toUpperCase(java.util.Locale)
either. Or, if you'd like to normalize "in the other direction," converting empty strings tonull
, you can useemptyToNull(java.lang.String)
.- Parameters:
string
- a string reference to check- Returns:
true
if the string is null or is the empty string
-
padStart
Returns a string, of length at leastminLength
, consisting ofstring
prepended with as many copies ofpadChar
as are necessary to reach that length. For example,padStart("7", 3, '0')
returns"007"
padStart("2010", 3, '0')
returns"2010"
See
Formatter
for a richer set of formatting capabilities.- Parameters:
string
- the string which should appear at the end of the resultminLength
- the minimum length the resulting string must have. Can be zero or negative, in which case the input string is always returned.padChar
- the character to insert at the beginning of the result until the minimum length is reached- Returns:
- the padded string
-
padEnd
Returns a string, of length at leastminLength
, consisting ofstring
appended with as many copies ofpadChar
as are necessary to reach that length. For example,padEnd("4.", 5, '0')
returns"4.000"
padEnd("2010", 3, '!')
returns"2010"
See
Formatter
for a richer set of formatting capabilities.- Parameters:
string
- the string which should appear at the beginning of the resultminLength
- the minimum length the resulting string must have. Can be zero or negative, in which case the input string is always returned.padChar
- the character to append to the end of the result until the minimum length is reached- Returns:
- the padded string
-
repeat
Returns a string consisting of a specific number of concatenated copies of an input string. For example,repeat("hey", 3)
returns the string"heyheyhey"
.- Parameters:
string
- any non-null stringcount
- the number of times to repeat it; a nonnegative integer- Returns:
- a string containing
string
repeatedcount
times (the empty string ifcount
is zero) - Throws:
IllegalArgumentException
- ifcount
is negative
-
commonPrefix
Returns the longest stringprefix
such thata.toString().startsWith(prefix) && b.toString().startsWith(prefix)
, taking care not to split surrogate pairs. Ifa
andb
have no common prefix, returns the empty string.- Since:
- 11.0
-
commonSuffix
Returns the longest stringsuffix
such thata.toString().endsWith(suffix) && b.toString().endsWith(suffix)
, taking care not to split surrogate pairs. Ifa
andb
have no common suffix, returns the empty string.- Since:
- 11.0
-