1 | initial version |
Kotlin Flow does not have a built-in feature to discard a previous value of the same type when it appears again in the flow. However, you can use operators such as distinctUntilChanged
to achieve this.
The distinctUntilChanged
operator filters out consecutive elements in the flow that are equal to the previous element. Here's an example:
val flow = flowOf(1, 2, 3, 3, 4, 4, 5)
flow
.distinctUntilChanged()
.collect { println(it) } // prints 1, 2, 3, 4, 5
In this example, the distinctUntilChanged
operator filters out the second occurrence of the value 3
and the second occurrence of the value 4
.
You can also provide a custom comparison function to the distinctUntilChanged
operator if you need to compare objects by a specific property or criteria.
data class Person(val name: String, val age: Int)
val flow = flowOf(
Person("Alice", 23),
Person("Bob", 25),
Person("Charlie", 23),
Person("Dave", 25),
Person("Eve", 23)
)
flow
.distinctUntilChanged { prev, next -> prev.age == next.age }
.collect { println(it) }
// prints:
// Person(name=Alice, age=23)
// Person(name=Bob, age=25)
// Person(name=Alice, age=23)
// Person(name=Bob, age=25)
// Person(name=Alice, age=23)
In this example, the distinctUntilChanged
operator compares Person
objects based on their age
property, which allows the operator to filter out consecutive elements with the same age.