mtumilowicz/java9-objects-new-methods

Java9: Overview of new methods in the Objects class.

java9-objects-new-methods

Java9: Overview of new methods in the Objects class.

preface

In Java 9, Objects class was extended with new static methods:

• T requireNonNullElse(T obj, T defaultObj) -
  • Returns the first argument if it is non-null and
  • otherwise returns the non-null second argument,
  • otherwise NPE.

  public static <T> T requireNonNullElse(T obj, T defaultObj) {
      return (obj != null) ? obj : requireNonNull(defaultObj, "defaultObj");
  }
  

• T requireNonNullElseGet(T obj, Supplier<? extends T> supplier) -
  • Returns the first argument if it is non-null
  • otherwise returns the non-null value of supplier.get(),
  • otherwise NPE.

  public static <T> T requireNonNullElseGet(T obj, Supplier<? extends T> supplier) {
      return (obj != null) ? obj
              : requireNonNull(requireNonNull(supplier, "supplier").get(), "supplier.get()");
  }
  

• int checkIndex(int index, int length) - Checks if index e [0; length).
  • returns index if it is within bounds of the range
• int checkFromToIndex(int fromIndex, int toIndex, int length) - Checks if [fromIndex; toIndex) c [0; length).
  • returns fromIndex if the sub-range within bounds of the range
• int checkFromIndexSize(int fromIndex, int size, int length) - Checks if [fromIndex; fromIndex + size) c [0; length).
  • returns fromIndex if the sub-range within bounds of the range

project description

We provide basics tests of above mentioned methods. Below we list the most interesting cases

• checkIndex
  • checkIndex(0, 0)

    @Test(expected = IndexOutOfBoundsException.class)
    public void checkIndex_index0_length0() {
        Objects.checkIndex(0, 0);
    }
    

  • checkIndex(3, 6)

    assertThat(Objects.checkIndex(3, 6), is(3));
    

• checkFromToIndex

  assertThat(Objects.checkFromToIndex(0, 3, 3), is(0));
  

• checkFromIndexSize

  @Test(expected = IndexOutOfBoundsException.class)
  public void checkFromIndexSize_size_lessThan0() {
      Objects.checkFromIndexSize(5, -3, 10);
  }