How to modify a field in each element of list in java 8 using stream

Question

I have the following classes:

class Employee 
{
    private String name;
    private List<Address> addresses;

    //...
    //Getters and setters for all fields
}

public class Address
{
    private String city;
    private Timestamp startDate;
    private Timestamp endDate;
    private String typeOfResidence;
    private String businessCode;
    private String businessType;


    //...
    //Getters and setters for all the fields
}

Now I have an employee object which has list of addresses. Based on businessCode, I need to populate businessType.

The businessCode is already populated.

I have a function

public String public getBusinessType(String businessCode){
...

business logic...

return businessType;
}

Now please help to update businessType field in each address element.

I am trying using

List<Address> l = employee.getAddress();

IntStream.range(0, l.size).forEach();

But not sure how to call getBusinessType for each address element and update the field in each address element.

employee.getAddress().forEach(a->a.setBusinessType(...));

Eran
– Eran

2018-04-25 07:29:19 +00:00
Commented Apr 25, 2018 at 7:29 — Eran
– Eran, Commented Apr 25, 2018 at 7:29

Eugene · Accepted Answer · 2018-04-25 07:32:36Z

3

You could do it in place without the need to stream:

yourList.forEach(x -> {
   x.setBusinessType(YourClass.getBusinessType(x.getBusinessCode())) 
})

answered Apr 25, 2018 at 7:32

Eugene

122k17 gold badges219 silver badges335 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Andreas Over a year ago

You don't need to make it a block. A void method is a valid lambda expression for forEach().

Eugene Over a year ago

@Andreas yup, I know that. I sometimes do that for clarity

jub0bs · Accepted Answer · 2018-04-25 08:40:21Z

2

The classic way using a for-each loop would be :

for(Address a :  employee.getAddress()){
    a.setBusinessType(getBusinessType(a.getBusinessCode()));
}

Using Streams it would be :

employee.getAddress().stream().forEach(a-> a.setBusinessType(getBusinessType(a.getBusinessCode())));

But (a good IDE would tell you that) the stream() is superfluous here; List.forEach() is sufficient:

employee.getAddress().forEach(a-> a.setBusinessType(getBusinessType(a.getBusinessCode())));

edited Apr 25, 2018 at 8:40

jub0bs

67.2k27 gold badges198 silver badges200 bronze badges

answered Apr 25, 2018 at 7:32

azro

54.2k9 gold badges39 silver badges75 bronze badges

Comments

Gagan Chouhan · Accepted Answer · 2018-04-25 07:34:58Z

-2

Refer below line.

    employee.getAddresses().forEach(employee-> employee.setCity("My City"))

answered Apr 25, 2018 at 7:34

Gagan Chouhan

3521 silver badge6 bronze badges

Comments

Hadi · Accepted Answer · 2018-04-25 08:39:41Z

-2

Should be like this

employee.getAddress().stream().map(address->address.setBusinessType(getBusinessType(address.getBusinessCode())))
         .collect(Colletors.toList());

also you can use replaceAll method.

To readability create UnaryOperator<T> and then use this function in replaceAll method.

 UnaryOperator<Address> updateBusinessType = address -> {
        address.setBusinessType(...);
        return address;
    };

employee.getAddress().replaceAll(updateBusinessType);

It can also be improved by defining a method in the Address class that update businessType property.

edited Apr 25, 2018 at 8:39

answered Apr 25, 2018 at 7:31

Hadi

17.3k4 gold badges41 silver badges63 bronze badges

2 Comments

Andreas Over a year ago

replaceAll() requires a UnaryOperator<Address>, but setBusinessType does not return a modified Address object.

Andreas Over a year ago

Sorry, I don't see the point of replacing all values in the list with the values that are already there. Using forEach() is much better. Using replaceAll() is just confusing, because we'd then sit there and try to figure out what you're replacing, and that's a waste of time, since you're not actually replacing the Address objects in the list. Or is that an exercise in code obfuscation. A bad one if so.

Collectives™ on Stack Overflow

How to modify a field in each element of list in java 8 using stream

4 Answers 4

2 Comments

Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

2 Comments

Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related