According to this topic: Collectors.mapping vs conventional Stream.map
I decided to conduct my own provisional test cases to find out an approximate performance difference between Collectors.mapping and Stream.map operations. In connection with the above, I created two helper methods that will supply stab data to my fake container.
private List<Employee> dataStab() {
List<Employee> employees = new ArrayList<>();
for (int i = 0; i < 10000000; i++) {
Employee employee = randomizeEmployeeParam();
employees.add(employee);
}
return employees;
}
private Employee randomizeEmployeeParam() {
return
new
Employee(
"Employee" + rand.nextInt(3000),
rand.nextInt(50),
1000 + (10000 - 1000) * rand.nextDouble());
}
I created two tests which are conducting accordingly Collectors.mapping and Stream.map operations.
@RepeatedTest(10)
void collectorsMapping() {
Instant start = Instant.now();
List<String> strings = employeeService.collectorsMapping(dataStab());
Instant finish = Instant.now();
long timeElapsed = Duration.between(start, finish).toMillis();
System.out.println(timeElapsed);
assertEquals(10000000, strings.size());
}
@RepeatedTest(10)
void streamMapAndCollect() {
Instant start = Instant.now();
List<String> mapAndCollect = employeeService.streamMapAndCollect(dataStab());
Instant finish = Instant.now();
long timeElapsed = Duration.between(start, finish).toMillis();
System.out.println(timeElapsed);
assertEquals(10000000, mapAndCollect.size());
}
Tests work so far but now I suppose to manually calculate an average time of these tests basing on the result in the run window in IntelliJ. Moreover In the long term if I will increase @RepeatedTest param to calculate the closest result this will be a little bit tedious. I want to know if it is possible to handle the duration param timeElapsed and calculate the average value for n repeated tests.
