HSLU PLAB assessment brain dump

A non comprehensive mixed list of questions and answers from the PLAB assessment. Some question might be missing because I forgot them. May this help you, as the description provided for which topics are questioned isn’t the clearest.

Do not treat this as a complete and definitive list, topics and questions might and probably change everytime.

General programming

Write the 2 methods divideBySeven and maxMinusMin, they calculate from the given numbers list how many are dividable by seven and the difference between the largest and smallest number.

public int divideBySeven(List numbers)
public int maxMinusMin(List numbers)

Nothing difficult just some basic for each and if conditions. maxMinusMin might also be solved using the Math library, but im unsure if that is graded worse or better.

for, while, recursion

Countdown from 9 with the 3 different methods.

Also not difficult if you have ever programmed.

Java inheritance and typing

Person

Employee Student

Prof

Choice between Complie, Runtime or no Error

Person p = new Student
----
Prof p = new Student
----
Person p = new Student
Employee e = (Employee) p
----
Employee e = new Prof
Person p = (Person) e

Forgotten most of the questions, but something in that direction

Questions about how inheritance works

If Prof is multiple inheritance Subtype If a Student object can be assigned into a Person variable.

Forgotten most of the questions, but something in that direction

Refactoring and UML Class Diagram

Given class public class TemperatureDisplayAndCalculation Which principle a given class was violating

• SRP
• Hidding
• etc..

public class Temperature {
	private int temp;
	private static final OFFSET

	public Temperature(int temp)
	public getCelcius()
	public getFahrenheit()
	public getKelvin
}

Fill in Class Diagram with missing methods and attributes

I didnt know how to represent static and final, maybe look that up. The above code is just my Interpretation, the class structure wasn’t strictly defined and had to be interpreted form the pre-refactor code.

JUnit

Write assert Why many test with few asserts or few tests with many asserts

No clue about junit so i forgot most questions, as I fluked this part

Write a class

• class name Student
• private attributes name and number
• getters (without setter) for name and number
• constructor with parameter name
• constructor sets number and increase number everytime new Student is called

Follow up question: How to create a Student object within the Student class with different constructors and not accessible/ callable outside of Student class. Example: new Student("name", -1)

Generally not difficult, but with no java knowledge I don’t know how to set number and increase it for every instance.

General Java questions

Hazy memory with this section, there were atleast 14 or so questions in total. But mostly just specific java knowledge.

what are and is the difference between checked and unchecked exceptions

how try-catch-finally works & what does finally “guarantee”

Java 8 Why were lambda and Stream API implemented

Class Hierarchy

Maybe has something to do with https://staff.fnwi.uva.nl/a.j.p.heck/Courses/JAVAcourse/ch3/s1.html but I really don’t know.

Overloaded function, why it doesnt work

private void process(ArrayList<int> param)
private void process(ArrayList<String> param)

Overriden Object.hashMap problematic with hashSet