Package com.google.common.base

Class Joiner

java.lang.Object

com.google.common.base.Joiner

@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.

Since:

2.0

Author:

Kevin Bourrillion

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	Joiner.MapJoiner	An object that joins map entries in the same manner as Joiner joins iterables and arrays.

Method Summary

Modifier and Type	Method	Description
<A extends Appendable> A	appendTo(A appendable, @Nullable Object[] parts)	Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
<A extends Appendable> A	appendTo(A appendable, Iterable<? extends @Nullable Object> parts)	Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
<A extends Appendable> A	appendTo(A appendable, Object first, Object second, @Nullable Object... rest)	Appends to appendable the string representation of each of the remaining arguments.
<A extends Appendable> A	appendTo(A appendable, Iterator<? extends @Nullable Object> parts)	Appends the string representation of each of parts, using the previously configured separator between each, to appendable.
StringBuilder	appendTo(StringBuilder builder, @Nullable Object[] parts)	Appends the string representation of each of parts, using the previously configured separator between each, to builder.
StringBuilder	appendTo(StringBuilder builder, Iterable<? extends @Nullable 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, @Nullable Object... rest)	Appends to builder the string representation of each of the remaining arguments.
StringBuilder	appendTo(StringBuilder builder, Iterator<? extends @Nullable Object> parts)	Appends the string representation of each of parts, using the previously configured separator between each, to builder.
String	join(@Nullable Object[] parts)	Returns a string containing the string representation of each of parts, using the previously configured separator between each.
String	join(Iterable<? extends @Nullable 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, @Nullable Object... rest)	Returns a string containing the string representation of each argument, using the previously configured separator between each.
String	join(Iterator<? extends @Nullable Object> parts)	Returns a string containing the string representation of each of parts, 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(char keyValueSeparator)	Returns a MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise.
Joiner.MapJoiner	withKeyValueSeparator(String keyValueSeparator)	Returns a MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

on

public static Joiner on(String separator)

Returns a joiner which automatically places separator between consecutive elements.

on

public static Joiner on(char separator)

Returns a joiner which automatically places separator between consecutive elements.

appendTo

@CanIgnoreReturnValue
public <A extends Appendable> A appendTo(A appendable,
                                         Iterable<? extends @Nullable Object> parts)
                                  throws IOException

Appends the string representation of each of parts, using the previously configured separator between each, to appendable.

Throws:

IOException

appendTo

@CanIgnoreReturnValue
public <A extends Appendable> A appendTo(A appendable,
                                         Iterator<? extends @Nullable Object> parts)
                                  throws IOException

Appends the string representation of each of parts, using the previously configured separator between each, to appendable.

Throws:

IOException

Since:

11.0

appendTo

@CanIgnoreReturnValue
public final <A extends Appendable> A appendTo(A appendable,
                                               @Nullable Object[] parts)
                                        throws IOException

Appends the string representation of each of parts, using the previously configured separator between each, to appendable.

Throws:

IOException

appendTo

@CanIgnoreReturnValue
public final <A extends Appendable> A appendTo(A appendable,
                                               @CheckForNull
                                               Object first,
                                               @CheckForNull
                                               Object second,
                                               @Nullable Object... rest)
                                        throws IOException

Appends to appendable the string representation of each of the remaining arguments.

Throws:

IOException

appendTo

@CanIgnoreReturnValue
public final StringBuilder appendTo(StringBuilder builder,
                                    Iterable<? extends @Nullable 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.

appendTo

@CanIgnoreReturnValue
public final StringBuilder appendTo(StringBuilder builder,
                                    Iterator<? extends @Nullable 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.

Since:

11.0

appendTo

@CanIgnoreReturnValue
public final StringBuilder appendTo(StringBuilder builder,
                                    @Nullable 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.

appendTo

@CanIgnoreReturnValue
public final StringBuilder appendTo(StringBuilder builder,
                                    @CheckForNull
                                    Object first,
                                    @CheckForNull
                                    Object second,
                                    @Nullable 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.

join

public final String join(Iterable<? extends @Nullable Object> parts)

Returns a string containing the string representation of each of parts, using the previously configured separator between each.

join

public final String join(Iterator<? extends @Nullable Object> parts)

Returns a string containing the string representation of each of parts, using the previously configured separator between each.

Since:

11.0

join

public final String join(@Nullable Object[] parts)

Returns a string containing the string representation of each of parts, using the previously configured separator between each.

join

public final String join(@CheckForNull
                         Object first,
                         @CheckForNull
                         Object second,
                         @Nullable Object... rest)

Returns a string containing the string representation of each argument, using the previously configured separator between each.

useForNull

public Joiner useForNull(String nullText)

Returns a joiner with the same behavior as this one, except automatically substituting nullText for any provided null elements.

skipNulls

public Joiner skipNulls()

Returns a joiner with the same behavior as this joiner, except automatically skipping over any provided null elements.

withKeyValueSeparator

public Joiner.MapJoiner withKeyValueSeparator(char keyValueSeparator)

Returns a MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise.

Since:

20.0

withKeyValueSeparator

public Joiner.MapJoiner withKeyValueSeparator(String keyValueSeparator)

Returns a MapJoiner using the given key-value separator, and the same configuration as this Joiner otherwise.