Module de.cuioss.java.tools
Package de.cuioss.tools.string

Class Joiner

java.lang.Object
de.cuioss.tools.string.Joiner
public final class Joiner extends Object
Inspired by Googles Joiner.

It uses internally the String.join(CharSequence, Iterable) implementation of java and provides a guava like wrapper. It focuses on the simplified Joining and omits the Map based variants.

Usage

 assertEquals("key=value", Joiner.on('=').join("key", "value"));
 assertEquals("key=no value", Joiner.on('=').useForNull("no value").join("key", null));
 assertEquals("key", Joiner.on('=').skipNulls().join("key", null));
 assertEquals("key", Joiner.on('=').skipEmptyStrings().join("key", ""));
 assertEquals("key", Joiner.on('=').skipBlankStrings().join("key", " "));

Migrating from Guava

In order to migrate for most case you only need to replace the package name on the import.

Changes to Guavas-Joiner

In case of content to be joined containing null-values and not set to skip nulls, skipNulls() it does not throw an NullPointerException but writes "null" for each null element. You can define a different String by calling useForNull(String)

In addition to skipEmptyStrings() it provides a variant skipBlankStrings()

Author:
Oliver Wolff

  • Constructor Details

  • Method Details

    • on

      public static Joiner on(String separator)
      Returns a Joiner that uses the given fixed string as a separator. For example, Joiner.on("-").join("foo", "bar") returns a String "foo-bar"
      Parameters:
      separator - the literal, nonempty string to recognize as a separator
      Returns:
      a Joiner, with default settings, that uses that separator

    • on

      public static Joiner on(char separator)
      Returns a Joiner that uses the given fixed string as a separator. For example, Joiner.on('-').join("foo", "bar") returns a String "foo-bar"
      Parameters:
      separator - the literal, nonempty string to recognize as a separator
      Returns:
      a Joiner, with default settings, that uses that separator

    • useForNull

      public Joiner useForNull(String nullText)
      Parameters:
      nullText - to be used as substitution for null elements
      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 one, except automatically skipping null-values

    • skipEmptyStrings

      public Joiner skipEmptyStrings()
      Returns:
      a joiner with the same behavior as this one, except automatically skipping String-values that evaluate to an empty String

    • skipBlankStrings

      public Joiner skipBlankStrings()
      Returns:
      a joiner with the same behavior as this one, except automatically skipping String-values that evaluate to a blank String as defined within MoreStrings.isBlank(CharSequence)

    • join

      public String join(Iterable<?> parts)
      Parameters:
      parts - to be joined
      Returns:
      a string containing the string representation of each of parts, using the previously configured separator between each.

    • join

      public String join(Iterator<?> parts)
      Parameters:
      parts - to be joined
      Returns:
      a string containing the string representation of each of parts, using the previously configured separator between each.

    • join

      public String join(Object... parts)
      Parameters:
      parts - to be joined
      Returns:
      a string containing the string representation of each of parts, using the previously configured separator between each.