Java Streams - Change field of an element

Question

I've been googling for a while, but I couldn't find the answer I am looking for.

I have a stream of products, and each one of those contains these fields:

private String ID;
private float price;
private int quantity;

I need to change the quantity field of a specific product without consuming the rest of the stream. Is it possible?

How can I search for this element (by product ID) and then change the value of quantity field?

I was thinking I could use .peek(), but I couldn't figure out how to achieve this.

rgettman · Accepted Answer · 2015-06-29 23:42:16Z

5

Assuming that you have a setter method for the quantity, you can use peek to change the value. Test for the product ID you want, then call the setter, all in a lambda expression (a Consumer).

stream.peek( p -> {
    if ("YourID".equals(p.getID()))
    {
         p.setQuantity(newQuantity);
    }
});

edited Jun 29, 2015 at 23:42

answered Jun 29, 2015 at 23:32

rgettman

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2 Comments

mohsenmadi Over a year ago

Is it safe to modify a peek element? Aren't peek elements presumably read-only and thread-safe?

Artem Over a year ago

just verified that you can modify elements like that using peek. I think when you peek you just ignore return value of the lambda function, but can use setters of the stream element for example

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