Modify property value of the objects in list using Java 8 streams

Question

I have a list of Fruit objects in ArrayList and I want to modify fruitName to its plural name.

Refer the example:

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Answer 1

just for modifying certain property from object collection you could directly use forEach with a collection as follows

collection.forEach(c -> c.setXyz(c.getXyz + "a"))

Answer 2

If you wanna create new list, use Stream.map method:

List<Fruit> newList = fruits.stream()
    .map(f -> new Fruit(f.getId(), f.getName() + "s", f.getCountry()))
    .collect(Collectors.toList())

If you wanna modify current list, use Collection.forEach:

fruits.forEach(f -> f.setName(f.getName() + "s"))

Answer 3

You can use just forEach. No stream at all:

fruits.forEach(fruit -> fruit.setName(fruit.getName() + "s"));

Answer 4

You can do it using streams map function like below, get result in new stream for further processing.

Stream<Fruit> newFruits = fruits.stream().map(fruit -> {fruit.name+="s"; return fruit;});
        newFruits.forEach(fruit->{
            System.out.println(fruit.name);
        });

Answer 5

You can use peek to do that.

List<Fruit> newList = fruits.stream()
    .peek(f -> f.setName(f.getName() + "s"))
    .collect(Collectors.toList());