Java - Top 10 most viewed questions on Stack Overflow

This questions are covering essential parts of Java and because of that we all should know and understand them!
Rating: 4.6 out of 5 (14 ratings)
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🚀 References on objects, how Java handles them internally, NullPointerException
🚀 Comparison of objects via == and equals.
🚀 How to create and fill files with the help of streams
🚀 What does call by value and call by reference mean? And what does Java use?
🚀 Syntactical sugar like the for-each-loop
🚀 and many more


  • You should know the basics of Java.


In this course we are going to examine the top 10 most viewed Java question on Stack Overflow since creation of this platform (*state October 2019)

Stack Overflow itself has according to wikipedia over 10 million registered users and has exceeded over 16 million questions.

This is why I believe that every software developer should get in touch with them. They are covering the essential parts of the programming language and because of that we all should know about them.

I will explain everything what you will need to first understand the questions and then be able to answer them on your own.

What topics can you expect within this course?

* I will explain to you what references on objects are and how Java saves them internally. We take a closer look to the so called null reference that often results in NullPointerExceptions.

* We get to know several data structures, such as Maps, HashMaps, Sets and many more.

* How do I compare two strings, or more general two objects with each other? And what has Java's String pool to do with it?

* We become acquainted with syntactical abbreviations like the for-each-loop or try-with-resource statement.

* We answer the eternal question if Java is a call by reference or call by value language or maybe both?

* How can I create random numbers in general or within specific range? And what do I have to take account of, if I am developing multi-threaded applications?

* We learn what FileOutputStreams and PrintWriters are for and how to use them to create files and fill them with datas.

* And many more

Who this course is for:

  • This course could be interesting for all Java developers out there.

Course content

1 section13 lectures2h 25m total length
  • Download of slides and sources
  • Question 1: "How do I convert a String to an int in Java?"
  • Question 2: "How do I declare and initialize an array in Java?"
  • Question 3: "How do I generate random integers within a specific range in Java?"
  • Question 4: "How do I compare strings in Java?"
  • Question 5: "How to split a string in Java"
  • Question 6: "Iterate through a HashMap"
  • Question 7: "Initialization of an ArrayList in one line"
  • Question 8: "How do I create a file and write to it in Java?"
  • Question 9: "What is a NullPointerException, and how do I fix it?"
  • Question 10: "How does the Java ’for each’ loop work?"
  • Add- on Question: "Is Java “pass-by-reference” or “pass-by-value”?"
  • The End


Selbstständiger Informatiker
Armin Kerscher
  • 4.5 Instructor Rating
  • 55 Reviews
  • 7,452 Students
  • 4 Courses


ich heiße Armin Kerscher, bin stolzer Papa, Oracle zertifizierter Java-Entwickler und studierter Diplom-Informatiker.

Ich erlangte mein Wissen über die Softwareentwicklung, vor allem in Java, aber auch anderen IT-Themen während meines Studiums (Universität Würzburg) und konnte dies im Anschluss dessen in der freien Wirtschaft als Diplom-Informatiker weiter ausbauen.

Eines meiner Ziele ist es nun, anderen dadurch zu helfen, in dem ich mit ihnen mein Wissen teile und dadurch auch meine Faszination an Java und der ganzen Informatik weitergebe.



my name is Amin Kerscher. I am a proud father, an oracle certified Java developer and a studied computer scientist.

I gained my knowledge about Java and the whole computer science during my studies and expanded it afterwards in the free economy.

One of my goals is to help other people by transferring my knowledge and to share my fascination in Java and the whole computer science.