CODEWITHSUNDEEP
functionjava-8
Dewey Banks
Dewey Banks

Reputation: 323

Java Function chaining

I'm trying to work out why the following code fails to compile:

Function<Employee, String> getLastName = (Employee employee) -> {
    return employee.getName().substring(employee.getName().indexOf(" ") + 1);
};

Function<Employee, String> getFirstName = (Employee employee) -> {
    return employee.getName().substring(0, employee.getName().indexOf(" "));
};

Function chained = getFirstName.apply(employees.get(2).andThen(getFirstName.apply(employees.get(2))));

Can't all Functions be cahined in java 8?

Upvotes: 2

Views: 8152

Answers (1)

Eugene
Eugene

Reputation: 121048

Exactly, andThen is applied to the result from that Function, for example:

Function<Employee, String> chained = getFirstName.andThen(x -> x.toUpperCase());

x -> x.toUpperCase() (or this can be replaced with a method reference String::toUpperCase) is applied to the String result from getFirstName Function.

How do you imagine chaining them? One Function returns String, so that makes it impossible to chain. But you can return both those fields via a single Function:

 Function<Employee, String[]> bothFunction = (Employee employee) -> {
        String[] both = new String[2];
        both[0] = employee.getName().substring(employee.getName().indexOf(" ") + 1);
        both[1] = employee.getName().substring(0, employee.getName().indexOf(" "));
        return both;
    };

Upvotes: 6

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