public final class StringJoiner extends Object
StringJoiner
is used to construct a sequence of characters separated by a delimiter and optionally starting with a supplied prefix and ending with a supplied suffix.
Prior to adding something to the StringJoiner
, its sj.toString()
method will, by default, return prefix + suffix
. However, if the setEmptyValue
method is called, the emptyValue
supplied will be returned instead. This can be used, for example, when creating a string using set notation to indicate an empty set, i.e. "{}"
, where the prefix
is "{"
, the suffix
is "}"
and nothing has been added to the StringJoiner
.
Collectors.joining(CharSequence)
,
Collectors.joining(CharSequence, CharSequence, CharSequence)
Constructor and Description |
---|
StringJoiner(CharSequence
Constructs a
StringJoiner with no characters in it, with no
prefix or
suffix , and a copy of the supplied
delimiter .
|
StringJoiner(CharSequence
Constructs a
StringJoiner with no characters in it using copies of the supplied
prefix ,
delimiter and
suffix .
|
Modifier and Type | Method and Description |
---|---|
StringJoiner |
add(CharSequence
Adds a copy of the given
CharSequence value as the next element of the
StringJoiner value.
|
int |
length()
Returns the length of the
String representation of this
StringJoiner .
|
StringJoiner |
merge(StringJoiner
Adds the contents of the given
StringJoiner without prefix and suffix as the next element if it is non-empty.
|
StringJoiner |
setEmptyValue(CharSequence
Sets the sequence of characters to be used when determining the string representation of this
StringJoiner and no elements have been added yet, that is, when it is empty.
|
String |
toString()
Returns the current value, consisting of the
prefix , the values added so far separated by the
delimiter , and the
suffix , unless no elements have been added in which case, the
prefix + suffix or the
emptyValue characters are returned
|
public StringJoiner(CharSequencedelimiter)
StringJoiner
with no characters in it, with no
prefix
or
suffix
, and a copy of the supplied
delimiter
. If no characters are added to the
StringJoiner
and methods accessing the value of it are invoked, it will not return a
prefix
or
suffix
(or properties thereof) in the result, unless
setEmptyValue
has first been called.
delimiter
- the sequence of characters to be used between each element added to the
StringJoiner
value
NullPointerException
- if
delimiter
is
null
public StringJoiner(CharSequencedelimiter, CharSequence prefix, CharSequence suffix)
StringJoiner
with no characters in it using copies of the supplied
prefix
,
delimiter
and
suffix
. If no characters are added to the
StringJoiner
and methods accessing the string value of it are invoked, it will return the
prefix + suffix
(or properties thereof) in the result, unless
setEmptyValue
has first been called.
delimiter
- the sequence of characters to be used between each element added to the
StringJoiner
prefix
- the sequence of characters to be used at the beginning
suffix
- the sequence of characters to be used at the end
NullPointerException
- if
prefix
,
delimiter
, or
suffix
is
null
public StringJoinersetEmptyValue(CharSequence emptyValue)
StringJoiner
and no elements have been added yet, that is, when it is empty. A copy of the
emptyValue
parameter is made for this purpose. Note that once an add method has been called, the
StringJoiner
is no longer considered empty, even if the element(s) added correspond to the empty
String
.
emptyValue
- the characters to return as the value of an empty
StringJoiner
StringJoiner
itself so the calls may be chained
NullPointerException
- when the
emptyValue
parameter is
null
public StringtoString()
prefix
, the values added so far separated by the
delimiter
, and the
suffix
, unless no elements have been added in which case, the
prefix + suffix
or the
emptyValue
characters are returned
public StringJoineradd(CharSequence newElement)
CharSequence
value as the next element of the
StringJoiner
value. If
newElement
is
null
, then
"null"
is added.
newElement
- The element to add
StringJoiner
public StringJoinermerge(StringJoiner other)
StringJoiner
without prefix and suffix as the next element if it is non-empty. If the given
StringJoiner
is empty, the call has no effect.
A StringJoiner
is empty if add()
has never been called, and if merge()
has never been called with a non-empty StringJoiner
argument.
If the other StringJoiner
is using a different delimiter, then elements from the other StringJoiner
are concatenated with that delimiter and the result is appended to this StringJoiner
as a single element.
other
- The
StringJoiner
whose contents should be merged into this one
StringJoiner
NullPointerException
- if the other
StringJoiner
is null
public int length()
String
representation of this
StringJoiner
. Note that if no add methods have been called, then the length of the
String
representation (either
prefix + suffix
or
emptyValue
) will be returned. The value should be equivalent to
toString().length()
.
StringJoiner