The method filter (predict ) in Java – stream type is not applicable to parameters ((E) – > {})

How to set the value in Java 8 in the filter? I want to set emailid to null, where firstname is Raj How can I do this in Java 8?

public class EmployeeDemo {
    public static void main(String[] args) {
        Employee e1 = new Employee("John","Kerr","john.kerr@gmail.com");
        Employee e2 = new Employee("Parag","Rane","john.kerr@gmail.com");
        Employee e3 = new Employee("Raj","Kumar","john.kerr@gmail.com");
        Employee e4 = new Employee("Nancy","Parate","john.kerr@gmail.com");

        List<Employee> employees = new ArrayList<>();
        employees.add(e1);
        employees.add(e2);
        employees.add(e3);
        employees.add(e4);

        employees.stream().filter(e -> {
            if(e.getFirstName().equals("Raj")) {
                e.setEmail(null);
            }
        }).
    }
}

Solution

The filter method should return Boolean. I don't think there should be any side effects In your case, a simple loop will do the job:

for(Employee employee: employees) {
    if(e.getFirstName().equals("Raj")) {
        e.setEmail(null);
    }
}

But if you really want to use streaming:

employees.stream() //get stream
    .filter(e -> e.getFirstName().equals("Raj")) //filter entries with first name Raj
    .forEach(e -> e.setEmail(null)); //for each of them set email to null

Or (if you want to process the entire list and all the items returned change:

employees.stream() //get stream
    .map(e -> {
        if(e.getFirstName().equals("Raj")) {
            e.setEmail(null);
        }
        return e;
    })
    .collect(Collectors.toList());