#Jedit edite jar files code#

You can use the Scanner class to interact with the user, even without a fancy user interface!

#Jedit edite jar files code#

Then the code uses the Scanner class to read what the user typed. This program prompts the user for their name, which they can enter by typing into the command prompt and pressing enter. Now we can compile and run this code, and it works! Hooray! You donвЂ™t want to use a fancy word processor like Microsoft Word though, because that kind of editor adds formatting and stuff that we donвЂ™t want in our code. I use jEdit, but you can use Notepad or whatever came with your computer. Eventually weвЂ™ll use a fancier editor, but for now letвЂ™s stick with doing things the вЂњmanualвЂќ way. To better understand whatвЂ™s going on behind the scenes, weвЂ™re going to create our files using a basic text editor, and weвЂ™re going to compile and run our files using the command prompt. The Processing editor makes that easy, but it hid a lot of the details from us. In Processing, we used the Processing editor to write and run our sketches. This tutorial assumes that youвЂ™ve already been through the Processing tutorials and understand what code is, and what objects and classes are. Replacing the period with another single-byte character is easy enough: just overwrite the 2E with another byte (for example, 7E for '~').Now that you installed Java, itвЂ™s time to write some code! To verify that this was part of the constant pool, I inspected the preceding 3 bytes: 01 00 01, that is, this 2E is a string ( 01) of one byte ( 00 01). To quickly find the constant pool, I searched for another string that was easier to find: ' lines]' from line 1196 in the source. However, since the period weвЂ™re looking for is represented by the single byte 2E in UTF-8, it was actually relatively straightforward. Since most hex editors (including mine) display non-printing bytes as periods, it seems like locating the string in the constant pool was like finding a particular piece of hay in a haystack.

I then navigated to org/gjt/sp/jedit/textarea and opened the file TextAreaPainter$PaintText.class with a hex editor. This is particularly handy, since changing the period to another character only requires changing the one literal in the constant pool.ДЇirst, I unzipped the jedit.jar from my jEdit installation into a directory. Since the period is represented in the source as a string literal, the compiler will add the literal to the constant pool in the class file. That line happens to be part of the PaintText private class. Looking at the source code for TextAreaPainter, I found the line of code that draws the period (line 1207 in jEdit 4.3.2). For strings, the type is 01 followed by 2 bytes that represent the number of bytes in the string (high order byte first), and then the string bytes encoded as (slightly modified) UTF-8.Д«rowsing through the jEdit JavaDocs, I noticed that. has some methods pertaining to EOL markers (namely getEOLMarkersPainted() and getEOLMarkerColor()), so that seemed like the natural starting point. Each constant in the pool is prefixed with one byte representing the type. The constant pool consists of an array of any literal data that appeared in the source code.

A class file is a binary file with a particular structure that includes, among other things, the constant pool and the bytecode itself. jar extension, inside of which is a hierarchy of class files. ThatвЂ™s exactly what I did.ДЇirst, some background on JAR and class files. The next best option (in my mind, anyway) is to fire up the good olвЂ™ hex editor and change the bytecode.

However, even if I had the JDK installed, I donвЂ™t feel like waiting for jEdit to compile. Unfortunately, thereвЂ™s no setting in jEdit that allows me to change the character used for the EOL marker, but that doesnвЂ™t mean itвЂ™s unchangeable! Since jEdit is open-source, one option is to modify the source code and recompile the application. Some programming languages also feature periods as a part of their syntax, which can also lead to confusion. Mostly, displaying periods in comments often leads to me thinking that IвЂ™m at the end of a sentence when IвЂ™m not. But one thing that has always bothered me about jEditвЂ™s end-of-line (EOL) markers is that theyвЂ™re displayed as periods. One feature that I make extensive use of is the вЂњEnd of line markersвЂќ which allow me to easily see if there are any extraneous spaces at the ends of lines. It has all the features youвЂ™d expect from a modern text editor and, being written in Java, itвЂ™s highly portable. Changing the end-of-line marker in jEdit without recompiling 14 January 2011