Conditional Actions

How to handle success and failure scenarios

We'll now delve into a set of methods that allow you to take conditional actions based on the state of a result. They provide a cleaner and more expressive way to handle success and failure scenarios, eliminating the need for lengthy if/else blocks.

Handling Success

We can use Result::ifSuccess to specify an action that must be executed if the result represents a successful outcome. This method takes a consumer function that will be applied to the success value wrapped by the result.

@Test
void testIfSuccess() {
  // Given
  List<Object> list = new ArrayList<>();
  Result<Integer, String> result = success(100);
  // When
  result.ifSuccess(list::add);
  // Then
  assertEquals(100, list.getFirst());
}

In this example, ifSuccess ensures that the provided action (adding the success value to the list) is only executed if the parsing operation is successful.

Handling Failure

On the other hand, we can use Result::ifFailure method to define an action that must be taken when the result represents a failure. This method also takes a Consumer that will be applied to the failure value inside the result.

@Test
void testIfFailure() {
  // Given
  List<Object> list = new ArrayList<>();
  Result<Integer, String> result = failure("ERROR");
  // When
  result.ifFailure(list::add);
  // Then
  assertEquals("ERROR", list.getFirst());
}

Here, ifFailure ensures that the provided action (adding the failure value to the list) is only executed if the parsing operation fails.

Handling Both Scenarios

Finally, Result::ifSuccessOrElse allows you to specify two separate actions: one for when the operation succeeded and another for when it failed. This method takes two consumer functions: the first for handling the success case and the second for handling the failure case.

@Test
void testIfSuccessOrElse() {
  // Given
  List<Object> list1 = new ArrayList<>();
  List<Object> list2 = new ArrayList<>();
  Result<Long, String> result1 = success(100L);
  Result<Long, String> result2 = failure("ERROR");
  // When
  result1.ifSuccessOrElse(list1::add, list1::add);
  result2.ifSuccessOrElse(list2::add, list2::add);
  // Then
  assertEquals(100L, list1.getFirst());
  assertEquals("ERROR", list2.getFirst());
}

In this example, ifSuccessOrElse simplifies conditional logic by providing a single method to handle both success and failure scenarios, making the code more concise and readable.

Conclusion

We explained how to handle success and failure scenarios using these three methods. They provide a powerful way to perform conditional actions based on the state of a Result, streamlining your error handling and making your code more readable and maintainable.