we worked for exam with our friends. I tried to explain manifest file, talking about how to do things. But I see that I did know why to register activities to androidManifest.xml. Still do not know :). Does anyone have an idea?
The manifest file is used by the system to know what kind of components do the application have. Without registering your Activities/Services/Receivers/Content Providers the system would have to scan and parse the whole apk every time someone wants to use a specific component to find it. This would be really slow, that's why there is the AndroidManifest.xml, which is a small file, and it can be parsed fast to find the required component.
Manifest file describes the following features...
Version Number and Version Code:
This is useful, when you are uploading the application in Google play or go for upgrade the existing published apk.
2.minSdk and targetSdk:
mentioned your min and max version number your application supports.
3.application tag:
used to set the first activity or home activity when you launch an application from laucher.
4.activity tag:
the list of all activities in the application declared as child tag in application tag for the easier navigation to activity manager.
When we switch one activity to another activity, the activity manager checks whether this activity is declared in manifest file or not. If not found throws exception.
Uses: Developer can have look at all the activities at a glance (By Manifest file)
5.Filter tags: By intent filters in activity tag, User can open any kind of application activity.
Uses permission and Uses features:
All application resources are declared here.
example: Internet connectivity is needed for your application, Uses WIFI in your application.
Related
Does the Android Manifest check for the available components to be used before an application starts running, or does the system check for the Android Manifest every time a new component is being instantiated? By components I mean activities, services, etc...
What is the process involved?
Also, can an application still go back and forth to check on the android manifest even after it is running to check on xml activity attributes such as the android:name, android:label, or even intent filters, for different purposes such as to see whether a component to be used has already been defined?
Well to say it in a simple way-
Manifest contains permission like- "SD card read/write permission". So, while installing an app if you don't have a SD card than your won't get installed.
Again manifest contains "minimum SDK version"- which checks what OS version you have in your mobile, if your mobile OS version is less than the minimum version defined in manifest than the app won't install in your mobile.
In the manifest you have a list of all the activities and services too. So, without adding these in the manifest- your activities/services wont work.
So, these sort of checking and permissions are in manifest - the information the system must have before it can run any of the app's code.
Hope i have been able to keep it short and simple :-D
The manifest is a part of the app - it gets packaged with the app in its installation APK.
The manifest tells the system what APIs the application will use. When the app is installed, the system tells the user what sets of potentially sensitive APIs the application will use (as listed int he manifest) and if the user allows the app to be installed the system then assumes that the use of those APIs is permitted.
The OS will not permit the app to use other sensitive APIs that the app did not declare in the manifest.
Android Manifest file contains important information like the Java package name of the application, permissions, descriptions about activities,services... The system must have these information before running the app code.By this reason, the system doesn´t check the Android Manifest in runtime.
More here:
Android Manifest - Android Developer
We specify current activity and start activity for an intent and we call it through the method startService(). So why do we need to mention that activity in manifest again?
Indexing (what can your app do?)
I can answer at least part of the why for Activities. The manifest is also where you declare your IntentFilter which is how the system understands what your application does. i.e. should your activity be an illegible choice when the user is trying to take a picture? choose a file? share a piece of text? In addition to that the IntentFilter also tells the Launcher application that you would like to have your activity included in the Applications drawer.
Configuring (what is your main activity?)
There are also several configuration options that you can set on Activities which have to be done in the manifest i.e. SingleTop. Without the declaration in the manifest there would be no place to declare these configurations.
Time Saving (where can the system find your service?)
The manifest file is used by the system to know what kind of components do the application have. Without registering your Activities/Services/Receivers/Content Providers the system would have to scan and parse the whole apk every time someone wants to use a specific component to find it. This would be really slow, that's why there is the AndroidManifest.xml, which is a small file, and it can be parsed fast to find the required component.
Sources: Why do Activities/Services need to be explicitly added to the Android manifest? why acitivies have to be registered in manifest file
Each android application you build will include a file called
AndroidManifest.xml which is placed in the root of the project
hierarchy. So why is it important? Because it lets you define the
structure and metadata of your android application and its components.
http://simpledeveloper.com/android-application-manifest-file/
if I have a Service or an Activity that I want to be started only by another Activity in my app, do I need to declare it in the manifest? I.e., I always launch a secondary activity from the primary activity of my app that directly points the secondary activity's class (no intent filter resolution), is still necessary to declare the secondary activity in the manifest?
And what if I don't want anyone outside my app to be able to launch my secondary activity?
1.YES
2.YES
3.set exported false in the manifest.
Read here for more information
What is Manifest?
Manifest file for an android application is a resource file which contains all the details needed by the android system about the application. It is a key file that works as a bridge between the android developer and the android platform. It helps the developer to pass on functionality and requirements of our application to Android. This is an xml file which must be named as AndroidManifest.xml and placed at application root. Every Android app must have AndroidManifest.xml file. AndroidManifest.xml allows us to define,
The packages, API, libraries needed for the application.
Basic building blocks of application like activities, services and etc.
Details about permissions.
Set of classes needed before launch.
Do I need to declare it in the manifest?
Yes
Is still necessary to declare the secondary activity in the manifest?
Yes
What if I don't want anyone outside my app to be able to launch my secondary activity?
android:exported="false"
We must declare in AndroidManifresh according to https://developer.android.com/guide/topics/manifest/activity-element.html
Declares an activity (an Activity subclass) that implements part of
the application's visual user interface. All activities must be
represented by elements in the manifest file. Any that are
not declared there will not be seen by the system and will never be
run.
I have been trying to figure this out on the web with no information whatsoever as to what this actually does. The Google Manifest information says:
Allows an application to set the maximum number of (not needed) application processes that can be running.
I am thinking this is not a third party app permission but I need to be sure, its for our embedded device.
My guess is that this limits the number of processes that one application can have open when calling android:process=".RemoteActivity" in the manifest.
Anyone? Thank you.
It's a development/debug intended permisson. And just do what it says. Remember that when you run an app, android creates a process for all it's activities. This is, if you start opening the different activities of your application, you use the same process. However, Android let's you choose if an activity uses the main process or another new one. That's why this permission exists.
Sources:
http://developer.android.com/guide/topics/fundamentals/processes-and-threads.html
http://developer.android.com/reference/android/Manifest.permission.html#SET_PROCESS_LIMIT
I am interested in activating another application's activity. I know from reading the Android SDK that it's probably better to do this with an implicit intent. However, this activity doesn't reside in an application I own, so I don't know the action and category and data flags on the intent-filter.
How can I examine an Android applications metadata like the activity classes and the intent-filters for those activities (if declared in the manifest)?
Thanks!
I would try this.
Check on openintents
Contact the developer.
Use android-apktool too see the app's manifest.
It might be illegal to use android-apktool. Use it under your own risk.
There is one more solution: you could run this app and look into logcat. All intents are logged, so you could see what is called up. You won't see extra data though.