Method useForNull

guava/src/com/google/common/base/Joiner.java:276–294

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

(String nullText)

   * nullText} for any provided null elements.
   */
  public Joiner useForNull(String nullText) {
    checkNotNull(nullText);
    return new Joiner(this) {
      @Override
      CharSequence toString(@Nullable Object part) {
        return (part == null) ? nullText : Joiner.this.toString(part);
      }

      @Override
      public Joiner useForNull(String nullText) {
        throw new UnsupportedOperationException("already specified useForNull");
      }

      @Override
      public Joiner skipNulls() {
        throw new UnsupportedOperationException("already specified useForNull");
      }
    };
  }

  /**
   * Returns a joiner with the same behavior as this joiner, except automatically skipping over any