Develop Reference

How to add your code to Android application?

I have an application that I want to modify by adding my own little code.
In many sites, I looked through the methods of decompilation, editing, recompilation, but I still could not find the answer to my question.
How can I add my Java code to a compiled Android application?

WDYM? Android apps are often obfuscated before compiling which makes it very hard to understand the code.
Your question doesn't make sense to me. If you decompiled it, just open the files with any IDE and edit them?! You said you read about editing and recompilation... Well then, why cant you edit?
Note: What are you trying to do? If it isnt an offline game, then it's illegal (probably the terms of service of the app state that) and if you are trying to increase your coins or something there are simpler ways to do that. Learn about app development first and then try something more diffictult like this.

Java and HID Communication

I'm looking to write a Linux/Windows/Mac Java HID controller for a simple wireless HID interface device. I've tinkered around with the USB4Java LibUsb library to no avail, and I've been steered in the direction of the JavaHIDAPI.
Unfortunately for me, I really have no idea what I'm doing beyond a pretty decent higher level programming skill set (C#/VB.Net), and switching over to this is killing me.
The directions that I found said that I would first need to compile the HIDAPI library found here. It said it would build something called hidapi-jni.dll (which it didn't).
Anyway, I think this is where I need to go since the HID does nothing but simply sends and receives signals to and from a wireless control (and responds to signals received).
Is there any step-by-step tutorial for using the JavaHIDAPI for this? Or is there a better library? (I noticed that this is a bit... dated).
I tried myself with the following:
static{ System.loadLibrary("hidapi"); }
.
.
.
public static void main(string[] Args) throws . . . {
ClassPathLibraryLoader.loadNativeHIDLibrary();
HIDDevice dev = HIDManager.getInstance().openById(VEND_ID, PROD_ID, null);
.
.
.
}
The issue into which I am running is that (besides the fact that the HIDAPI doesnt seem to be building into HIDAPI-jni.dll) is that the HIDManager.openById(. . .) always returns null. Also, I moved the hidapi.dll that was built into the C:...\Java...\bin directory... or something, I'm sure it's right because there wasn't any unsatisfied link error. It's really frustrating because there doesn't seem to be any newbies guide to Java and HID anywhere.
What am I doing wrong here?

I'm a bit late to answer this question, but I've written a library called hid4java that might solve your problem.
It's based on Java Native Access (JNA) which is a lot simpler than faffing about with complex JNI incantations.
I had to write it because javahidapi is out of date and the underlying signal11/hidapi code has moved on considerably. The older versions of the hidapi library had problems on OS X with attach/detach events which have now been fixed so an upgrade is necessary.
Also I found it impossible to claim a USB HID device through usb4java on OS X so I ended up writing this library to solve that problem.
Hope it helps.

So the issue, I discovered, was with native libraries.
I was able to get the application to work by copying the .dll from the .jar file and referencing it, but more important, I'm going to rebuild the .java class file responsible for loading the library and add the
System.loadLibrary();
call. When the JavaHidApi ClassPathLibraryLoader.loadNativeHIDLibrary(); method is called it doesn't load the library upon successfully writing it out to the temp file which is mildly annoying. Doing this will eliminate the necessity for manually loading the library from a static location...
Thank you for pointing me in the correct direction.

This element neither has attached source nor attached Javadoc and hence no Javadoc could be found (for Google Maps)

I've quite searched in stackoverflow and google but I couldn't find a solution. Everytime I hover over an object which comes from the google play services library it gives me the message I have as a title. I mean that I don't have such a problem problem when hovering over "Activity" or "super.onCreate" etc. for exapmle. I have imported the google play services into my project and added the library. I've tried a lot of solutions proposed in here but none helped. Plz be as much specific and thorough as you can be cause I'm still a newbie in android.

Javadocs are those comment blocks you see above code in libraries; they're parsed in a special way such that they can be used, for example, to provide information about a class or method on hover.
The Javadocs for Activity and other Android SDK code are provided. But external libraries don't necessarily come with them, or may be provided in a separate jar. Depending on the IDE you're using, the instructions for adding them are different. You can see some instructions for Eclipse by another user, here: https://stackoverflow.com/a/17601734/2203712

Hover the object Type and the object's method would give you more information you want.
Hovering to the object itself, will never tell much

Transitioning from VS2010 to Eclipse IDE for Android/Java dev

I wonder if someone can help me... I've been developing VB.Net for years and C++/VB before that. I've also got some PHP experience. I'm now moving to Java to write an app for my Android mobile. I'm trying to use MOTODev Studio (Which extends eclipse)
I've not developed in Java before so it's a bit of a learning curve anyway. I'm fairly confident I'll be able to work out the important bits but I'm in a new IDE in a new language developing for a new platform.
As I'm new to Java, I was hoping to be able to rely on auto-code generation, intellisense, etc. I'm starting to think this was either very optimistic or I'm using eclipse very poorly.
For example, I know I need to override the OnClickListener() event but am unsure of the exact syntax. In VS, I'd just start typing Override in a class and up would pop intellisense with everything I can override and the appropriate signature, however, in eclipse none of the intellisense options seem to apply when I type public voidor #Override. Is this because I'm doing something wrong/is eclipse intellisense incomplete not very good?
In VS there's a bar at the top of the code page which lists objects in the file on the left and methods of the current object on the right. Does eclipse have an equivalent? If so, where?
I've managed to use the IDE to the extent that I've got a "Hello World" installed on my mob so it's more code generation techniques than windows/dialogues/etc.
I suppose what I really need is for someone to recommend some good resources to help me transition. I'd also appreciate any comments or advice from others that have done similar
Thanks in advance

So you learning three items at once
Language (Java)
Platform (Android)
Tool (Eclipse)
Here are my two cents for each of them:
Java - besides annotations guide already mentioned by Falmarri all java tutorials on oracle site are worth seeing you can find them here
Android - From my point of view very good entering points into android development are Android Developer Dev guide and API Demos project which demonstrates many android aspects ( You can add this project into your workspace in Eclipse via ->New Android Project-> Select from sample ->Choose target version -> Click OK , Voila you have new project in your workspace with a lot of useful android related code, describing many advanced and not so advanced topics). BTW Android developers blog is worth reading but
it usually covers more advanced topics
Eclipse - Falmarri already pointed and pretty good tutorial about Eclipse, I from my side would suggest to start from Help-> Help Contents -> Java Development User Guide
It covers all basic tasks and concepts. For your particular problem with overriding ( actually implementing) an interface method you've to first indicate that your class implements View.OnClickListener via class MyClass implements OnClickListener at this point eclipse will notice that you claiming to implement interface but didn't actually implemented some of it methods ( in this situation onClick(View v)) and will mark class declaration with error marker. Go to your class declaration and press Ctrl + 1 ( also known as "quick fix") and you will get some options to fix broken code. At the other hand if you really want to override parent class method you can press Ctrl + Space in a class body ( e.g not inside the method) and you will get option to override avalible methods.
Hope it helps

http://download.oracle.com/javase/tutorial/java/javaOO/annotations.html
yes, it's the default java perspective. Have you even installed the IDE yet?
http://www.vogella.de/articles/Eclipse/article.html

I'm not entirely sure I fully understand your questions, but if I'm in a Java class in Eclipse that implements some Interface and I want to implement methods I either select the quick fix (Ctrl+1) for the compiler error telling me I'm not implementing the Interface or I trigger content assist (Ctrl+Space) in the class body to get a list of methods to override. And with the bar you mention, do you mean something like the breadcrumb navigation (Alt+Shift+B)?

Converting equations to java for android?

I am a cameraman and I want to make an app for my Moto Droid that will
calculate my depth of field given four inputs.
I am literally brand
new to javascript and this programming stuff, so I was wondering if
anyone could help me out.
I have a very basic GUI set up using Droiddraw which allows me to
input my 4 variables, which are:
Focus (#+id/focust)
Focal Length (#+id/flt)
Aperture (#+id/apt)
Circle of Confusion (#+id/coct)
Equations for this calculation are located here
for example...
to get hyperfocal distance I need to get: ((f^2)/(N*c))+f
all of these variables will be drawn from inputs in the GUI, but I don't know how to call them, how to write the actual math, and how to address the results so I can make them appear in the "results area" on the bottom of the screen.
I've never done java before and I only want to make this app because the existing ones don't fit my needs.
Can someone help?
Thanks!

If I'm not mistaken, DroidDraw is a tool for building the XML user interface description used by the Java API. If you want to program for Android in JavaScript, something like PhoneGap might be a better choice. It lets you build real Android application using HTML and JavaScript.
On the other hand, if you want to use the XML and Java APIs, then you should probably run through the Android tutorials. The first one is Hello, World.
Since you're just getting started with programming, I can't stress tutorials enough. It's true that your idea shouldn't be too hard to implement, but you need to understand the basics first.
I don't mean to give the impression that one style (PhoneGap vs. Java and XML) is better. For your purposes, either should be fine. It's more a question of what you prefer. Java/XML is the paradigm supported by Google, and provides access to more functionality. On the other hand, if you already know HTML or JavaScript (or are interested in learning them), PhoneGap will certainly provide everything you need. I think PhoneGap is also intended to make it easier for beginners, though I haven't used it, so I don't know how successful they have been.
The XML file that is generated by DroidDraw can't be used within PhoneGap. If you do choose to use PhoneGap, then you will need to build the interface in HTML. You might be able to use something like DreamWeaver or FrontPage or one of any number of HTML editors to help you with this step.
The XML file is just a description of an interface. When you start your application, the Android platform uses this description to build the user interface that you see. Once that has happened, you can move data from the interface to Java, or from Java to the interface, without any hassle. You certainly won't be limited by the XML interface description - it's pretty flexible.
If you've been going through the Android tutorials, then it might be best to forget that I even mentioned PhoneGap. It's a wildly different alternative that is the right choice for some people and some applications. But the Android tutorials won't help you to understand it. I only brought it up because you mentioned JavaScript in your original post.