@GwtCompatible public final class Strings extends java.lang.Object
String
or CharSequence
instances.Modifier | Constructor and Description |
---|---|
private |
Strings() |
Modifier and Type | Method and Description |
---|---|
static java.lang.String |
commonPrefix(java.lang.CharSequence a,
java.lang.CharSequence b)
Returns the longest string
prefix such that
a.toString().startsWith(prefix) && b.toString().startsWith(prefix) , taking care not to
split surrogate pairs. |
static java.lang.String |
commonSuffix(java.lang.CharSequence a,
java.lang.CharSequence b)
Returns the longest string
suffix such that
a.toString().endsWith(suffix) && b.toString().endsWith(suffix) , taking care not to
split surrogate pairs. |
static java.lang.String |
emptyToNull(java.lang.String string)
Returns the given string if it is nonempty;
null otherwise. |
static boolean |
isNullOrEmpty(java.lang.String string)
Returns
true if the given string is null or is the empty string. |
static java.lang.String |
nullToEmpty(java.lang.String string)
Returns the given string if it is non-null; the empty string otherwise.
|
static java.lang.String |
padEnd(java.lang.String string,
int minLength,
char padChar)
Returns a string, of length at least
minLength , consisting of string appended
with as many copies of padChar as are necessary to reach that length. |
static java.lang.String |
padStart(java.lang.String string,
int minLength,
char padChar)
Returns a string, of length at least
minLength , consisting of string prepended
with as many copies of padChar as are necessary to reach that length. |
static java.lang.String |
repeat(java.lang.String string,
int count)
Returns a string consisting of a specific number of concatenated copies of an input string.
|
(package private) static boolean |
validSurrogatePairAt(java.lang.CharSequence string,
int index)
True when a valid surrogate pair starts at the given
index in the given string . |
public static java.lang.String nullToEmpty(@Nullable java.lang.String string)
string
- the string to test and possibly returnstring
itself if it is non-null; ""
if it is null@Nullable public static java.lang.String emptyToNull(@Nullable java.lang.String string)
null
otherwise.string
- the string to test and possibly returnstring
itself if it is nonempty; null
if it is empty or nullpublic static boolean isNullOrEmpty(@Nullable java.lang.String string)
true
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
use String.isEmpty()
instead of this method, and you won't need special null-safe forms
of methods like String.toUpperCase(java.util.Locale)
either. Or, if you'd like to normalize "in the other
direction," converting empty strings to null
, you can use emptyToNull(java.lang.String)
.
string
- a string reference to checktrue
if the string is null or is the empty stringpublic static java.lang.String padStart(java.lang.String string, int minLength, char padChar)
minLength
, consisting of string
prepended
with as many copies of padChar
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.
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 reachedpublic static java.lang.String padEnd(java.lang.String string, int minLength, char padChar)
minLength
, consisting of string
appended
with as many copies of padChar
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.
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
reachedpublic static java.lang.String repeat(java.lang.String string, int count)
repeat("hey", 3)
returns the string "heyheyhey"
.string
- any non-null stringcount
- the number of times to repeat it; a nonnegative integerstring
repeated count
times (the empty string if
count
is zero)java.lang.IllegalArgumentException
- if count
is negativepublic static java.lang.String commonPrefix(java.lang.CharSequence a, java.lang.CharSequence b)
prefix
such that
a.toString().startsWith(prefix) && b.toString().startsWith(prefix)
, taking care not to
split surrogate pairs. If a
and b
have no common prefix, returns the empty
string.public static java.lang.String commonSuffix(java.lang.CharSequence a, java.lang.CharSequence b)
suffix
such that
a.toString().endsWith(suffix) && b.toString().endsWith(suffix)
, taking care not to
split surrogate pairs. If a
and b
have no common suffix, returns the empty
string.static boolean validSurrogatePairAt(java.lang.CharSequence string, int index)
index
in the given string
.
Out-of-range indexes return false.