Call "Optional#isPresent()" before accessing the value

Question

As i am getting Call "Optional#isPresent()" before accessing the value in Sonar issues for the below Code Snippet , please help me to resolve this issue.

List <Department> deptList =new ArrayList();

List<Student> studList=new ArrayList();

Department dept= studList.stream().min(comparator.comparing(Department::getDepartmentNo)).get();

Call "Optional#isPresent()" before accessing the value.

If you run this code, you'll get an exception. That's what it's warning you about. — shmosel, Oct 31 '17 at 18:20

score 10 · Answer 1 · answered Oct 31 '17 at 18:23

Optional#get() throws an exception if there is nothing inside Optional. Sonar wants you to check the optional before getting the value like in the snippet below, but I won't recommend it as the whole idea of Optional class is to prevent null pointer exceptions

Optional<Department> deptOpt= studList.stream().min(comparator.comparing(Department::getDepartmentNo));

Department department = null;
if(deptOpt.isPresent())
    department = deptOpt.get();
}

A better way of doing things is the fololowing:

Department department = deptOpt.orElse(Department::new);

In this case, deptOpt returns a default Department object in case Optional doesn't contain any value (is empty).

Anyway - whatever approach you choose should fix your problem with Sonar.

What if I already know that the value is present since I already checked it? — Christian Vincenzo Traina, Aug 31 '23 at 07:42

score 8 · Accepted Answer · answered Oct 31 '17 at 18:20

For your code working, use at least one of the safe options from Option (ha, redundancy in words allowed here)

Department dept= studList.stream().min(comparator.comparing(Department::getDepartmentNo)).orElse(null);

Where "null" should be one value for the case of the empty list, I don't know the context, that's why I put null, please, don't use null!, select a correct value

Call "Optional#isPresent()" before accessing the value

2 Answers2