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
.
Public Constructor Summary
StringJoiner(CharSequence delimiter)
Constructs a
StringJoiner with no characters in it, with no
prefix or suffix , and a copy of the supplied
delimiter . |
|
StringJoiner(CharSequence delimiter, CharSequence prefix, CharSequence suffix)
Constructs a
StringJoiner with no characters in it using copies
of the supplied prefix , delimiter and suffix . |
Public Method Summary
StringJoiner |
add(CharSequence newElement)
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 other)
Adds the contents of the given
StringJoiner without prefix and
suffix as the next element if it is non-empty. |
StringJoiner |
setEmptyValue(CharSequence emptyValue)
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 |
Inherited Method Summary
Public Constructors
public StringJoiner (CharSequence delimiter)
Constructs a 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.
Parameters
delimiter | the sequence of characters to be used between each
element added to the StringJoiner value |
---|
Throws
NullPointerException | if delimiter is null
|
---|
public StringJoiner (CharSequence delimiter, CharSequence prefix, CharSequence suffix)
Constructs a 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.
Parameters
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 |
Throws
NullPointerException | if prefix , delimiter , or
suffix is null
|
---|
Public Methods
public StringJoiner add (CharSequence newElement)
Adds a copy of the given CharSequence
value as the next
element of the StringJoiner
value. If newElement
is
null
, then "null"
is added.
Parameters
newElement | The element to add |
---|
Returns
- a reference to this
StringJoiner
public int length ()
Returns the length of the 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()
.
Returns
- the length of the current value of
StringJoiner
public StringJoiner merge (StringJoiner other)
Adds the contents of the given 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.
Parameters
other | The StringJoiner whose contents should be merged
into this one |
---|
Returns
- This
StringJoiner
Throws
NullPointerException | if the other StringJoiner is null |
---|
public StringJoiner setEmptyValue (CharSequence emptyValue)
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. 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
.
Parameters
emptyValue | the characters to return as the value of an empty
StringJoiner |
---|
Returns
- this
StringJoiner
itself so the calls may be chained
Throws
NullPointerException | when the emptyValue parameter is
null
|
---|
public 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
Returns
- the string representation of this
StringJoiner