BlueJ Developer Hiring Guide

Hiring Guide for BlueJ Engineers

Ask the right questions to secure the right BlueJ talent among an increasingly shrinking pool of talent.

BlueJ is an integrated development environment (IDE) specifically designed for teaching Java and object-oriented programming. Developed in the late 1990s by Michael Kölling and John Rosenberg at Monash University, Australia, it was later maintained by the University of Kent, UK. The software simplifies the learning process with its visual interface and interactive capabilities. It has been adopted by many educational institutions worldwide to introduce students to Java programming. The software is open-source and freely available for use, making it a popular choice among educators and students alike.

First 20 minutes

General BlueJ knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you debug a program in BlueJ?

You would use the 'Debug' menu to set breakpoints, step into methods, step over methods, and continue execution. You can also inspect the state of objects and variables.

What is the purpose of the 'Object Bench' in BlueJ?

The 'Object Bench' is used to create and interact with objects. You can invoke methods on these objects and inspect their state.

How would you compile a program in BlueJ?

You would right-click on the class that contains the main method and select 'Compile'. If there are no syntax errors, the class will be compiled successfully.

What are the main components of the BlueJ interface?

The main components of the BlueJ interface are the 'Project' window, the 'Editor' window, the 'Object Bench', and the 'Terminal' window.

How would you create a new project in BlueJ?

To create a new project in BlueJ, you would go to 'Project' in the menu bar and select 'New Project'. You would then specify the project name and location.

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What youre looking for early-on

Does the candidate show a willingness to learn and adapt?

The tech industry is always evolving, so it's important for a candidate to show that they are willing to learn new things and adapt to changes.

Is the candidate able to work within a team?

Software development often involves working in teams. The candidate should be able to demonstrate their ability to work well with others.

How well does the candidate communicate?

Communication skills are important in any role, but especially in development where the candidate may need to explain complex concepts to non-technical team members.

Do they have experience with Java?

BlueJ is specifically designed for Java programming. Therefore, a candidate should have a solid background in Java to be successful in this role.

Can they demonstrate problem-solving abilities?

Problem-solving is a crucial skill in any programming or development role. The candidate should be able to demonstrate this through their responses to technical questions or hypothetical scenarios.

Does the candidate have a solid understanding of BlueJ?

BlueJ is a development environment that is often used in introductory programming classes. A candidate should have a firm understanding of how to use it and its functionalities.

Next 20 minutes

Specific BlueJ development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

How would you use the 'Code Pad' in BlueJ?

The 'Code Pad' is used to execute Java expressions and statements. You would type the code in the 'Code Pad' and press Enter to execute it.

What is the purpose of the 'Inspector' in BlueJ?

The 'Inspector' is used to inspect the state of an object. It displays the values of the object's fields.

How would you create a new class in BlueJ?

You would right-click in the 'Project' window and select 'New Class'. You would then specify the class name and type.

What are the benefits of using BlueJ for beginners in Java programming?

BlueJ simplifies the learning process by providing a clean and simple interface, visualizing the class structure, and allowing interaction with objects. It also has built-in tools for testing and debugging.

Describe the difference between 'step into', 'step over', and 'step out' in BlueJ's debugger.

'Step into' executes the next line of code and if it's a method call, it goes inside the method. 'Step over' executes the next line of code but doesn't go inside method calls. 'Step out' completes the execution of the current method and goes back to the caller method.

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The ideal back-end app developer

What you’re looking to see on the BlueJ engineer at this point.

At this point, the candidate should display proficiency in Java, as BlueJ is a Java development environment. They should also show strong problem-solving skills and a deep understanding of object-oriented programming concepts. Red flags include lack of hands-on experience or difficulty explaining complex concepts clearly.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with BlueJ.

What does this simple BlueJ code do?

public class HelloWorld {
 public static void main(String[] args) {
 System.out.println("Hello, World!");
 }
}

This code prints 'Hello, World!' to the console.

What does this BlueJ code do?

public class Test {
 public static void main(String[] args) {
 int x = 5;
 int y = ++x;
 System.out.println(y);
 }
}

This code increments the value of 'x' before assigning it to 'y'. So, 'y' will be 6.

What will be the output of this BlueJ code?

public class ArrayTest {
 public static void main(String[] args) {
 int[] arr = {1, 2, 3, 4, 5};
 for(int i: arr) {
 System.out.print(i + " ");
 }
 }
}

This code will print the elements of the array 'arr' in a single line with a space between each element. So, the output will be '1 2 3 4 5 '.

What does this BlueJ code do?

public class ThreadTest extends Thread {
 public void run() {
 System.out.println("Thread is running.");
 }
 public static void main(String args[]) {
 ThreadTest t1=new ThreadTest();
 t1.start();
 }
}

This code creates a new thread and starts it. The new thread then prints 'Thread is running.' to the console.

What does this BlueJ code do?

public class Student {
 private String name;
 public Student(String name) {
 this.name = name;
 }
 public String getName() {
 return name;
 }
}

This code defines a 'Student' class with a private 'name' field. It also provides a constructor to initialize the 'name' and a getter method to retrieve the 'name'.

What will be the output of this BlueJ code?

public class Test {
 public static void main(String[] args) {
 try {
 int x = 0;
 int y = 5 / x;
 } catch (ArithmeticException e) {
 System.out.println("Arithmetic Exception");
 } catch (Exception e) {
 System.out.println("Exception");
 }
 }
}

This code will print 'Arithmetic Exception' because it tries to divide a number by zero, which is not allowed and throws an ArithmeticException.

Wrap-up questions

Final candidate for BlueJ role questions

The final few interview questions for a BlueJ candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

How would you use BlueJ in a collaborative development environment?

BlueJ has built-in support for Git and SVN, which are version control systems that allow multiple developers to work on the same project. You can commit changes, update the project, and resolve conflicts directly in BlueJ.

What are the features of BlueJ that support test-driven development?

BlueJ supports test-driven development with its 'Unit Test' tool, which allows you to write and run tests for your classes. It also has a 'Test Results' window that displays the results of the tests.

How would you handle exceptions in BlueJ?

You would use try-catch blocks to handle exceptions. The code that might throw an exception is placed in the try block, and the code to handle the exception is placed in the catch block.

What are the steps to execute a method in BlueJ?

You would first create an object of the class that contains the method. You would then right-click on the object in the 'Object Bench' and select the method. If the method requires parameters, you would enter them in the dialog box.

Describe the difference between creating an object and creating a class in BlueJ.

Creating a class is defining a new type with its own methods and fields. Creating an object is instantiating a class, which means creating an instance of the class with its own state.

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BlueJ application related

Product Perfect's BlueJ development capabilities

Beyond hiring for your BlueJ engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in BlueJ projects, and can engage in multiple capacities.