I want to make an application which embeds an activity in a tabbed UI from a number of applications. As far as I know it's officially disabled due to the security matter but probably some hacks exist!
I have heard of two ways:
converting the activity to a type of Fragment
using LocalActivityManager class which is currently deprecated.
I already tried both of them and failed due to lack of my ability. If there is something I missed or another approach, let me know!
Note that I can modify those because I have a source code of them.
I want to make an application which embeds an activity in a tabbed UI from a number of applications.
That is not possible.
As far as I know it's officially disabled due to the security matter but probably some hacks exist!
I doubt it.
I have heard of two ways
Neither of them are related to your problem as originally stated.
Note that I can modify those because I have a source code of them.
Then combine them into one application, creating one APK file. At that point, then you can start exploring converting UIs into fragments or otherwise combining things into a tabbed UI.
Related
Given the fact that I don't have very extensive experience when it comes to Android apps, I have a questions regarding the architecture of an application :
Are there any problems I can run into if I decide to create an application that has only one activity and I 'load' all the other content using fragments only ?
Thanks
No, this approach is absolutely all right. More than that, Fragments are more lightweight then Activities, so you can gain performance by using this approach. However, keep in mind, that Activity is designed to behave as a single user screen that serves for a concrete purpose, and Fragments are the parts of this screen. So your approach works well if the whole application should contain a single user screen according to the design, thus serving for a single concrete and properly defined purpose.
I have a full-fledged app which is NOT developed using Fragments. My confusion is that should I change it to have Fragments instead of Activities. The thing that I would like to tell is that I'm using only portrait orientation in my application and it is built, keeping in mind only phones, not tablets. So my question is, will it do any good if I change the whole structure of app and use Fragments.
As far as I know, Fragments should be used only If we want to reuse something. Any suggestion is appreciated.
Fragments can be used to create a dynamic and multi-pane user interface, and as such are ideally suited for tablets which have a lot more screen real estate to use up. Of course, on a phone the situation is a little different, you have a much smaller space to play with and sometimes it can be a struggle just to get one Activity fitting onto the screen without worrying about including multiple Fragments.
Fragments are very good for dynamic interfaces, and for helping with compatibility between Tablet and Phone. They are also able to communicate with each other much better than Activities can, so there are certainly advantages to using them even on a phone-only setup. (See FragmentsManager for some functionality they can be used for)
One example of use is illustrated in the diagram below (taken from Android Developer site)
This illustrates the flexibility of the Fragments, which on tablet can occupy the same screen, switching to a more Activity-like format on a phone. It is this kind of power that gives the Fragment such an advantage over an Activity.
So clearly there are advantages to switching to a Fragment orientated solution in terms of flexibility, but your original question states that you are targeting phones only, and only in portrait orientation.
Having an application that is already in existence with Activities, providing that it is a solution that you are happy with, and has good usability I would say there was no reason to switch to Fragments (unless you are looking for a challenge or have some spare time and fancy a tinker). While advantages exist, a drastic change such as adding Fragments could introduce bugs into your application and impact the user experience (at least for the short term).
Long term, if you are ever considering bringing tablet support into the fold or would like to use the landscape orientation, then it might be a good idea to start looking at what you can do with Fragments to improve the experience, and integrate this with the current flow of your phone application.
Otherwise, the current solution you have created will more than suffice, and as long as it is well received by your customer base I see no reason to change.
Of course, there is no harm familiarising yourself with the Fragment APIs for future projects, or in the event that it is time for a refresh of your current project's UI.
It is worth pointing out that Fragments are only supported natively from Android 3.0 (API level 11), and to support earlier devices you will require the Android Support package found in your installation. As such, if your current application targets 2.x devices, I would stick with an Activity based approach, for simplicity and .apk size, unless moving to a native API Level (like Android 3.0+). This is personal preference though and ultimately the answer to your original question will boil down to your personal preference.
Think of fragments as a way to modularize your code into manageable pieces. Each fragment represents a small piece of functionality and UI. This allows your to easily adjust your code to fit different scenarios.
Sure you don't plan on supporting tablets now (regardless of how you feel tablet users will install the app), think of larger size 5-6" devices and the potential of extending your app over to them. It is best to provide your app to as many devices as possible and the best apps will tailor the experience to the device.
The transition to Fragments doesn't have to be difficult. Take a small piece of functionality and move it over to a Fragment. Then you will see how easy and flexible the new pattern is. You don't need to rewrite the entire application as Activities and Fragments can work together.
I believe by skipping out on Fragments you are really making your development tasks much more difficult in the long run.
If you don't plan to support tablets in the future than leave it as it is. You won't gain anything when you convert your app to fragments.
The situation is different if you start a new application. I would use fragments from the beginning in order to be more flexible should the need arise to support other form factors in the future. Note that the functionality is available in the support library so you can use it also on older devices.
It is easier to set interaction between fragments than between activities.
In case of activities:
You need to use startActivityForResult()/onActivityResult();
Your custom types must implement Parcelable interface in order to be passed between activities;
You have to free all resources when your activity is paused/stopped.
In case of fragments:
Passing data is as easy as getting an instance of fragment from FragmentManager and calling a method on it;
No need to implement Parcelable;
You can hold references to "heavy" resources in activity which contains all of your fragments and initialise/release them only once (no need for initialisation/release for each fragment).
Also, an instance of Fragment is more lightweight than instance of Activity and takes less time and resources to be initialised/resumed.
In general, interaction between the components of your UI is cleaner, more elegant, easier to implement when you use fragments.
As far as your application or any of the application is concerned , it's better to use fragments and it causes no harm to your application and it also ease your burden while further extending your application for tablets also.So, better to start with the use of fragments in your application.
I've just finished converting my application to use fragments, because:
Wanted a tablet version
Wanted to use ViewPageIndicator and ViewPager with advanced views
Those are the most compelling reasons to use fragments.
It might be a little more work, but with significantly more tablets appearing on the market and fast adoption rate, perhaps it's worth considering supporting tablets with a nicer UI?
If you really don't want to do this and have no requirement for view paging using advanced views then there is no point over-engineering your project to make it use fragments for using fragments sake. You could argue you might learn about them, but when you come to use them in your next project, you can learn then (that is what I did and it worked out fine).
I’m not an Android pro though I’ve developed an app consisting of more than 50 activities which makes the app really large. After 8 weeks of developing, now there are problems which caused the app difficult to maintain and upgrade.
Major ones I’m dealing with are
I cannot pass object reference to activities’ constructors. In fact I found the mechanisms of startActivityForResult – Intent – onActivityResult really limiting and results in dirty code of many constants for actions per activity and a lot of switch case that is really hard to follow the flow of app.
Another problem is that I do not know how to manage the life cycle of the whole app as each activity has its own life cycle.
I had some successful experience with LWUIT and J2ME – polish which ignore J2ME MIDlets (similar to android activity) and implement their own architecture and windowing system with just one MIDlet as entry to the app. I’ve come up with the same idea for android.
To clarify, I’m thinking of an app with just one main Activity and other activities implemented as objects which extend View object and these views can be dynamically added to main activity FrameLayout and stack on each other. Activities’ logic can be implemented in such classes and I've even found a way to implement dialogs in this way.
Business and state objects can be passed to their constructor and it sounds good ignoring its side effect of writing a little more code. This way listeners can also be passed to views’ constructors which makes app UI switch and flow management easier.
But the questions are:
Is it a good practice?
Wouldn't it lead me to performance or memory issues?
I'm also aware of
Android: What is better - multiple activities or switching views manually?
Don't Overload a Single Activity Screen
Pattern one activity, multiple views. Advantages and disadvantages
None of these clearly address the issues regarding performance or practice with reasonable evidence or documented reference
Please someone help me with this
There are popular apps in market with only one or a few activities. They use fragments and switch them. I would prefer fragments over your approach. Although I think fragments are too complex for many purposes, for your use case it would be a good solution. Your UI behavior should be in fragments, and your activity is the controller part transferring data between your fragments. Fragments also have an own life cycle.
I don't like startActivityForResult either. If I have a set of activities - all providing data - and I don't know in which order they will be called, I prefer to use a singleton class then using intents for data transmission between activities. But you have to analyze your problem to get a good solution.
There is already an MVC framework built, PureMVC library.
I was wondering if instead of having to create a new class for each activity is it possible to create mulitiple activities within one class?
So define various layout xml for various activities within one class, instead of having to create new classes for each activity.
Thanks
No, you should put each activity in seperate class. Take a look at this question. Someone is wondering just the same thing as you.
Ricky,
Yes, you may have multiple "Activities" defined inside a single class. But there are a lot of obstacles and issues with doing so. Before I answer this question, two things must be understood:
What you are asking goes against the Android guidelines for development, and those guidelines are enforced in as many ways as they can be during the compilation process, so nothing I say here is insured to work across any or all API versions of the Android SDK.
Different development environments do their own checks and compile in slightly different ways. I will be speaking from the Eclipse side of development.
Techniques listed here are for education, but introduce a lot of issues. For self education and theory, it is a wonderful practice to explore. However, the goal of this answer is to educate you as to why the guideline should be followed rather than sidestepped.
Requirements for an Activity
The first thing to understand is that Android has specific points that must be met for an Activity to be run. It must: a) be declared in the manifest; b) have an intent-filter describing how it is to be used; c) be a public class; d) be a top-level class.
Multiple Activities, Same Parent Class
This means that you may create an Activity inside of another class (an inner Activity, so to speak), but it must be declared static and public. This limits your Activity in a huge number of ways. Calls to methods or members that are instance-related (not static) to the parent class are not possible. So you lose a lot of time and code hacking around this.
Second, it affects your Android XML declaration for your Activity. This is where the real trouble comes in, because while it can be done, it is very specific and there is not any supporting documentation to make that happen. But that's okay, you wanted to know if you could make ONE class for your Activities.
Multiple Activities, Same Class
Well, Android determines which Activity to run based on its Intent. You could declare the same class multiple times, but with different Names and Intent-filters. If this is the case, then you would have to determine what to do based on the Intent and the extras included. This would be done in your onCreate() method.
Doing things in this manner would mean that you would have to code for two Activities in every place that you would normally deal with one. This would make it much harder to track down bugs to support your product. It would also make every routine operation take longer as you would have to decide which method to perform. For instance, if you overrode onDraw(), you would have to know which Activity you were drawing. Its ultimately just a big schmorgasborg (sp? does anyone know how to spell that word?) of "what do I do?!"
The Real Question
Why would you want to do this anyway?
1. If the answer is to save yourself time navigating your own project, believe me... That won't really happen. Your code will be harder to read, interpret and debug.
If the answer is that you want to save file space, I would reconsider your project's priorities.
If the answer is that you want to share functionality, consider extending Activity and then extending your new sub class. How do you think they made the ListActivity or TabActivity to begin with?
If you want to save state, you can place state in SharedPreferences or your Application object (if you have extended it).
As you can see, no matter your needs, there are many other ways to go about it in a way that doesn't cause you or anyone else a hassle.
Hope this helps,
FuzzicalLogic
I just got done writing an Android Activity that allows other Activities to call it for some result (it's not intended to be a stand-alone Activity). I'm now working on the equivalent iOS application and can't find any resources for how I would enable similar functionality on iOS.
The situation: The tool I'm producing is intended to be used by other applications, rather than as a standalone application. The thing is, the GUI that needs to be presented to the user is rather involved so I'd like to be able to provide the developer with a "all-in-one" package that they can simply launch and get results from. Doing this in Android was very straight forward. I simply wrote an Activity and instructed the developer to launch this Activity for result. I've looked around and can't find a similar functionality to allow an iOS developer to do the same. What would be the best way to go about doing this?
I think part of the problem I'm having in finding resources is that I'm not entirely sure what what I'm making is called. A library? extension? plug-in? I would think a library doesn't have a GUI and it seems extensions and plug-ins are made for an extensible application (that is, one in which the user can install the extension/plug-in).
Your API could be à single call that would pop up a modal view. A target and selector can be specified to receive an answer. Supplying it to other developers means packing it into a "framework". I'm not sure if you can include resources.
There isn't really any equivalent. The closest you can come is having the second application call UIApplication's openURL with a custom scheme that is listened to by your app, and then when your app is done it would do the same with a custom scheme that is listened to by the calling app.
In practice, the iOS app would usually include the entire activity-equivalent as some sort of library, which at the high level would take the form of a UIViewController subclass that is presented modally and then calls a delegate method or completion selector of some sort on completion.
iPhone development is a different design than Android development, so you may need to rethink what it is you are trying to do.
Most likely you will want to look at just including the code in each program, initially, just so you can get it testable, but that may not be the best solution.
But, without knowing more details about what you are trying to do it is hard to give some suggestions as to better solutions.
For example, you may find LocalNotifications as one solution (http://useyourloaf.com/blog/2010/7/31/adding-local-notifications-with-ios-4.html), but again, it depends on what your needs are.
I found that using local notifications to call a REST service, then to process it and decide if I need to inform the user was helpful, as a replacement for how I used Intents in the Android application.