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Questions tagged [bluej]

BlueJ is a popular Java IDE aimed at teaching the principles of object oriented programming.

BlueJ is an open source platform written in Java that's especially aimed at beginner developers. It presents items to the user in a much more easy and intuitive format than more comprehensive IDEs such as Netbeans or Eclipse, helping people get started quickly and easily whilst also understanding what's going on.

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The latest version of BlueJ is available from the download page, here.

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1065 questions
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"int cannot be dereferenced" in Java

I'm fairly new to Java and I'm using BlueJ. I keep getting this "Int cannot be dereferenced" error when trying to compile and I'm not sure what the problem is. The error is specifically happening in my if statement at the bottom, where it says…
BBladem83
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Eclipse IDE Scope Highlighting?

When I first learned Java, I was using an IDE called "BlueJ." It had this feature called "Scope Highlighting" which made it very easy to read blocks of code. Now I've moved on from BlueJ and began using Eclipse. I'm currently in the process of…
David Meyer
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Can Eclipse dynamically evaluate expressions?

In some Java IDEs (BlueJ and DrJava, for example), the user can open an interaction window where Java expressions and statements can be typed in. The IDE quickly compiles and runs the code, displaying the returned value if necessary. In BlueJ, it's…
Barry Brown
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How to call a method function from another class?

I'm writing a java project that has three different classes. This is what i have have so far. I'm just stuck on how do you call a method function from another class to another class. I have written 2 classes already. I got the "Date" class and…
Chase
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Why can't BlueJ take into account my Java Home whereas Eclipse can

I want to install BlueJ manually for portability reason. I have set Java_Home and add Java bin directory to path environment variable. I'm using a symlink on c:\java which points to d:\java on sd card. Why BlueJ does not take them into account still…
user310291
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How to recompile with -Xlint:unchecked?

I keep getting this message in BlueJ/Java. http://cache.gyazo.com/19c325e77bbc120892d1035dcfda5377.png I know there are several other questions like this already on StackOverflow, but none of the answers were specific enough for me, a Java noob. For…
viggom555
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Iterating through a Java collection to make these balls bounce, any hints?

Apologies if the question isn't clear but I couldn't think of another way to phrase it. This is for a class assignment which I've been working at in BlueJ all weekend. I have to change a method (bounce) to let a user choose how many balls should be…
daveyboy
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JAVADOC for private methods (BlueJ)

I'm using BlueJ and I would like to generate the Javadoc of my whole project. I would like to show private methods on the Javadoc, is there any way to do it? BlueJ has a tool which makes the Javadoc, but BlueJ ignore private methods. Is just a…
Thorba
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IntelliJ: run a single Method, like BlueJ does

So I currently use IntelliJ (2017-3 if that matters), but on my current project I need to test single Methods with specific inputs (mostly text-Manipualtion), so I remembered BlueJ back from School, where you can create Objects and run single…
Hobbamok
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Why Am I Getting An NPE That Only Appears Occasionally When The Program is Run?

I'm writing a test class for my GiftSelector class using JUnit in BlueJ. When I run the testGetCountForAllPresents() method, I get a NullPointerException on the line: assertEquals(true, santasSelector.getCountsForAllPresents().get(banana) ==…
JC2188
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How to write a test class to test my code?

I want a test class to test this class but i dont know how to write it and i tried to see online but i still couldnt figure it out.I wrote the code on BlueJ, i'm trying to create the set game. import java.util.*; public class Deck { …
user2022871
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Call / Test Sorting Methods in Main Class

For reference I am programming Java in BlueJ. I am fairly new to the language and I am having trouble with sorting. I am trying to call / test all of the 5 sorting methods in the main class. I figured out how to call / test…
BBladem83
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6 answers

Removing Strings of given length from an ArrayList?

We are given a list of words in the form of an ArrayList as follows: public ArrayList getListOfStrings(){ ArrayList list = new ArrayList(); list.add("This"); list.add("is"); list.add("an"); …
user2895102
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How do I enter parameters for an ArrayList in BlueJ?

In BlueJ, if I write a method that takes an array as a parameter, then when I want to test that method with a method call I have to enter the elements with curly braces, so: {1,2,3} How do I do a method call for an ArrayList? Here is my code: import…
user1894469
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Accesing a method in the last object in a LinkedHashMap

I've got a LinkedHashMap that contains an object at key and one at value. I've used the code yourShots.keySet().toArray()[yourShots.size()-1] to return the last object of the keys. However, I am unable to access a method that the object has. I've…
Brian
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