You have already accepted and answer and this is a bit of a side-note but I have never been really happy with the streams API in Java. The design is very OO-centric and (ironically) somewhat procedural which can lead to very ugly (and unreadable) code IMO. It unfortunate since the features around function references that were introduced at the same time can avoid a lot of that noise. For that same reason, it's pretty easy to create reusable functions that clean things up. Here's how the first example looks once you introduce this:

public int inactiveSalaryTotal(List<Employee> employees) {
  return sum(map(filter(employees, Employee::isActive), Employee::getSalary);
}

This gives you something that is a bit more like how things are done in a true functional language. It's more concise and, I think, understandable. There are various ways these can be defined depending on your needs. I can provide some examples implementations if needed.

You have already accepted and answer and this is a bit of a side-note but I have never been really happy with the streams API in Java. The design is very OO-centric and (ironically) somewhat procedural which can lead to very ugly (and unreadable) code IMO. It's unfortunate since the features around function references that were introduced at the same time can avoid a lot of that noise. For that same reason, it's pretty easy to create reusable functions that clean things up. Here's how the first example looks once you introduce this:

public int inactiveSalaryTotal(List<Employee> employees) {
  return sum(map(filter(employees, Employee::isActive), Employee::getSalary);
}

This gives you something that is a bit more like how things are done in a true functional language. It's more concise and, I think, understandable. There are various ways these can be defined depending on your needs. I can provide some example implementations if needed.

You have already accepted and answer and this is a bit of a side-note but I have never been really happy with the streams API in Java. The design is very OO-centric which can lead to very ugly (and unreadable) code IMO. It unfortunate since the features around function references that were introduced at the same time can avoid a lot of that noise. For that same reason, it's pretty easy to create reusable functions that clean things up. Here's how the first example looks once you introduce this:

public int inactiveSalaryTotal(List<Employee> employees) {
  return sum(map(filter(employees, Employee::isActive), Employee::getSalary);
}

This gives you something that is a bit more like how things are done in a true functional language. It's more concise and, I think, understandable. There are various ways these can be defined depending on your needs. I can provide some examples implementations if needed.

You have already accepted and answer and this is a bit of a side-note but I have never been really happy with the streams API in Java. The design is very OO-centric and (ironically) somewhat procedural which can lead to very ugly (and unreadable) code IMO. It unfortunate since the features around function references that were introduced at the same time can avoid a lot of that noise. For that same reason, it's pretty easy to create reusable functions that clean things up. Here's how the first example looks once you introduce this:

public int inactiveSalaryTotal(List<Employee> employees) {
  return sum(map(filter(employees, Employee::isActive), Employee::getSalary);
}

This gives you something that is a bit more like how things are done in a true functional language. It's more concise and, I think, understandable. There are various ways these can be defined depending on your needs. I can provide some examples implementations if needed.