@GwtCompatible public class Joiner extends Object
An object which joins pieces of text (specified as an array, Iterable, varargs or even a Map) with a separator. It either appends the results to an Appendable or returns them as a String. Example:
Joiner joiner = Joiner.on("; ").skipNulls();
. . .
return joiner.join("Harry", null, "Ron", "Hermione");
This returns the string "Harry; Ron; Hermione". Note that all input elements are converted to strings using Object.toString() before being appended.
If neither skipNulls() nor useForNull(String) is specified, the joining methods will throw NullPointerException if any given element is null.
Warning: joiner instances are always immutable; a configuration method such as useForNull has no effect on the instance it is invoked on! You must store and use the new joiner instance returned by the method. This makes joiners thread-safe, and safe to store as static final constants.
// Bad! Do not do this!
Joiner joiner = Joiner.on(',');
joiner.skipNulls(); // does nothing!
return joiner.join("wrong", null, "wrong");
See the Guava User Guide article on Joiner.
| Modifier and Type | Class and Description |
|---|---|
static class |
Joiner.MapJoiner
An object that joins map entries in the same manner as
Joiner joins iterables and arrays. |
| Modifier and Type | Method and Description |
|---|---|
<A extends Appendable> |
appendTo(A appendable,
Iterable<?> parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to appendable. |
<A extends Appendable> |
appendTo(A appendable,
Iterator<?> parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to appendable. |
<A extends Appendable> |
appendTo(A appendable,
Object[] parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to appendable. |
<A extends Appendable> |
appendTo(A appendable,
Object first,
Object second,
Object... rest)
Appends to
appendable the string representation of each of the remaining arguments. |
StringBuilder |
appendTo(StringBuilder builder,
Iterable<?> parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to builder. |
StringBuilder |
appendTo(StringBuilder builder,
Iterator<?> parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to builder. |
StringBuilder |
appendTo(StringBuilder builder,
Object[] parts)
Appends the string representation of each of
parts, using the previously configured separator between each, to builder. |
StringBuilder |
appendTo(StringBuilder builder,
Object first,
Object second,
Object... rest)
Appends to
builder the string representation of each of the remaining arguments. |
String |
join(Iterable<?> parts)
Returns a string containing the string representation of each of
parts, using the previously configured separator between each. |
String |
join(Iterator<?> parts)
Returns a string containing the string representation of each of
parts, using the previously configured separator between each. |
String |
join(Object[] parts)
Returns a string containing the string representation of each of
parts, using the previously configured separator between each. |
String |
join(Object first,
Object second,
Object... rest)
Returns a string containing the string representation of each argument, using the previously configured separator between each.
|
static Joiner |
on(char separator)
Returns a joiner which automatically places
separator between consecutive elements. |
static Joiner |
on(String separator)
Returns a joiner which automatically places
separator between consecutive elements. |
Joiner |
skipNulls()
Returns a joiner with the same behavior as this joiner, except automatically skipping over any provided null elements.
|
Joiner |
useForNull(String nullText)
Returns a joiner with the same behavior as this one, except automatically substituting
nullText for any provided null elements. |
Joiner.MapJoiner |
withKeyValueSeparator(String keyValueSeparator)
Returns a
MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise. |
@CheckReturnValue public static Joiner on(String separator)
Returns a joiner which automatically places separator between consecutive elements.
@CheckReturnValue public static Joiner on(char separator)
Returns a joiner which automatically places separator between consecutive elements.
public <A extends Appendable> A appendTo(A appendable, Iterable<?> parts) throws IOException
Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
IOExceptionpublic <A extends Appendable> A appendTo(A appendable, Iterator<?> parts) throws IOException
Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
IOExceptionpublic final <A extends Appendable> A appendTo(A appendable, Object[] parts) throws IOException
Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
IOExceptionpublic final <A extends Appendable> A appendTo(A appendable, @Nullable Object first, @Nullable Object second, Object... rest) throws IOException
Appends to appendable the string representation of each of the remaining arguments.
IOExceptionpublic final StringBuilder appendTo(StringBuilder builder, Iterable<?> parts)
Appends the string representation of each of parts, using the previously configured separator between each, to builder. Identical to appendTo(Appendable,
Iterable), except that it does not throw IOException.
public final StringBuilder appendTo(StringBuilder builder, Iterator<?> parts)
Appends the string representation of each of parts, using the previously configured separator between each, to builder. Identical to appendTo(Appendable,
Iterable), except that it does not throw IOException.
public final StringBuilder appendTo(StringBuilder builder, Object[] parts)
Appends the string representation of each of parts, using the previously configured separator between each, to builder. Identical to appendTo(Appendable,
Iterable), except that it does not throw IOException.
public final StringBuilder appendTo(StringBuilder builder, @Nullable Object first, @Nullable Object second, Object... rest)
Appends to builder the string representation of each of the remaining arguments. Identical to appendTo(Appendable, Object, Object, Object...), except that it does not throw IOException.
@CheckReturnValue public final String join(Iterable<?> parts)
Returns a string containing the string representation of each of parts, using the previously configured separator between each.
@CheckReturnValue public final String join(Iterator<?> parts)
Returns a string containing the string representation of each of parts, using the previously configured separator between each.
@CheckReturnValue public final String join(Object[] parts)
Returns a string containing the string representation of each of parts, using the previously configured separator between each.
@CheckReturnValue public final String join(@Nullable Object first, @Nullable Object second, Object... rest)
Returns a string containing the string representation of each argument, using the previously configured separator between each.
@CheckReturnValue public Joiner useForNull(String nullText)
Returns a joiner with the same behavior as this one, except automatically substituting nullText for any provided null elements.
@CheckReturnValue public Joiner skipNulls()
Returns a joiner with the same behavior as this joiner, except automatically skipping over any provided null elements.
@CheckReturnValue public Joiner.MapJoiner withKeyValueSeparator(String keyValueSeparator)
Returns a MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise.