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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.

Useful Links

1093 questions
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Converting to binary - getting IndexOutOfBoundsException

Below is some code I'm working on, I thought I'd make myself a binary calculator to make my life slightly easier. However, when I run it, I get an error telling me that there is a Java.lang.StringIndexOutofBoundsException. I don't really know how to…
arsb48
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Java - OR / AND characters (|| &&) illegal in if-statement

I am coding a simple program using a scanner and now want to make sure the user only types "yes" or "no" by comparing the input to these words. I'm using a normal if-statement with || (pipes): if (!input.equals("yes") || !input.equals("no")) { …
LinusGeffarth
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ArrayList Book Search

I've to create a library system in bluej and it has to be able to search for a book. However, I have a problem. When I try and search for a book the result is always no books available... How do I sort this so the result shows the book is…
Chris Campbell
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Sharing a java project (different IDEs)

Me and my team were wondering how we could share our java project easily. I was thinking about using something like Google drive but it is quite tedious to download the files everytime any member wants to modify them. I know there exits easier ways…
Corvinus
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How to delete a folder containing other folders in Java?

Here is a code I tried: import java.io.*; public class file03 { public static void main(String[] args) { File f1 = new File("C:/tempo1/tempo"); f1.mkdirs(); File f2 = new File("C:/test"); if(!f2.exists()) { …
user3177527
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how to create a unique sequence of letter and numbers in constructor

I have a field call details which holds different sequence of letter and numbers, what i am trying to do is a Constructor that have a unique sequence of letter and numbers of length 8.
Mohamed Ghassar
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Creating an even and odd array of specific parameters from an original array

Write a program to accept 15 random numbers into a 1D array. Sort the array using Bubble Sort. After sorting, transfer and store all the even numbers and odd numbers into separate arrays. Display the unsorted original array and the sorted even and…
Anuj Kulkarni
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Java - pdfbox cannot import jar?

Hi there Please can someone help me with this simple problem I believe... I've already asked over 8 experts on a java chat website yet no-one can seem to help me :(. I have downloaded the jar files from http://pdfbox.apache.org/download.html. I have…
help-me please
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Is there a program similar to BlueJ that works for C# instead of java

I find BlueJ a great tool for plotting a program before diving in and I was wondering if there is a similar tool for C#?
DeusImoral
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Adding items to an ArrayList only if a similar item isn't on the list

Here's the code for the separate class Product which the ArrayList is based on. The chapter has us learning ArrayList, Loops, and Iterator so anything more advanced than that has not been covered and is not meant to be used to complete the…
user9603005
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1 answer

BlueJ Error: "Incompatible types: int cannot be converted java.lang.String" AND "Incompatible types: java.lang.String cannot be converted to int"

I'm very new to coding and after trying multiple solutions I came up with, I still can't figure out why what I'm doing is wrong. This is my full code: public class Student { private String name; private String grade; private String gender; …
Ann
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1 answer

GUI not showing up, Java (BlueJ)

Creating a Tic Tac Toe game. As of right now, the buttons have no purpose, and the game shouldn't work at all. All I am trying to do is set up the GUI for the game, which shows up sometimes I run it, but most of the time never shows up. I'm quite…
Thomas Bryk
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1 answer

Display code auto-complete suggestions in BlueJ while typing

I have been using BlueJ for over 5 years now. But when it comes to Game Development, I do need the Code complete feature, since it becomes difficult. For this I have to Switch to Eclipse or Sublime. I also know that Ctrl+Space triggers the code…
The Arcadian Pandit
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1 answer

Actual and formal arguments lists differ in length error

The below is a binary calculator I have been making, but when I try to run it, I get a "actual and formal arguments lists differ in length" error, and I do not know how to fix it. I can't really be sure, but it looks like a problem with trying to…
arsb48
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project hierarchy Idea rather then BlueJ

In some Coursera course the expected IDE is BlueJ. Right from the start, I would like to learn how to manage projects with more advanced IDE, like IntelliJ Idea. The teacher staff provided their framework which they prebuilt in BlueJ.app env. So…
MiniBug
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