I want to share streams of a socket connection between the activities of a tab view. In particular the tab activity creates the socket and gets the i/o streams,so i want that tabbed activities use these streams to retrieve informations without reconnect to the server each time i switch from a tab to another. I know i can use the application class to have a global state, but i don't know how.
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I have a Weather app with four Activities. The main/launcher activity is 'invisible' using...
android:theme="@android:style/Theme.Translucent.NoTitleBar"`
Aand is simply used to do a few checks (whether this is a new install, whether a network connection is available etc) before firing off one of the other Activities. The other Activities are UI-oriented - two simply display weather data pulled from a website and the third to provide a location 'picker' so the user can choose which area to show the weather for.
However, all four activities make use of a WeatherHelper object which basically does everything from checking for available SD card storage to maintaining preferences and pulling/formatting website pages.
So, my question(s)...what is the best way to have one instance of WeatherHelper which can be used by multiple activities and where/how are best to create it in my case?
I've been an OO programmer for a lot of years but I'm very new to Android and the design concepts - I've read a lot on the Android Developers site over the past weeks but I've stalled trying to decide on this.
I was playing a bit with adapters cursors and activities. Let's assume i have a cursor containing a query I've made (it doesn't matter if it's to DB or content provider). Now lets assume i bind some of the data (first two rows) to a list activity. Every click on one of those items should open a new list activity (i pass on the cursor index in the activity bundle). Now the question is, which sharing method will be most efficient and right from code point of view ?
1. I thought of trying to send the cursor object in the intent itself (hoping it implemented runnable) but I'm not so sure it's that efficient since the query may contain many rows which will need to be parceled, and i the other intents uses only a few (say 4-5 columns of each row) it's a real waste.
2. Thought of trying to create the array list for my other list screen adapter and serialize it to the intent (again use serialize and intent to pass on the data) but again i fear for efficiency penalty.
3. my last solution was to use static cursor member in my first activity, with package permission, it will work and be relatively efficient, but I'm not so sure regarding memory efficiency and code structure, i'm not fond of using static variables in any case.
Is there another sharing method that i don't know off, if two activities share the same process and application, then they also share memory space, then it should be easy to pass variables from one to another, the question is what's the easiest way without serializing ?
I did some digging, but couldn't find a clear answer. I have an application with TabActivity as the main activity. I have some computing and network communication that needs to be done when user clicks on the big red jolly "DO IT" button. One tab hosts the form with "DO IT" button, while the other tabs display the results from computing (each tab displays different part of results). The computing is done as AsyncTask as it's supposed to be (afaik).
Now the question is, what is the best way to share the results between the tabbed activities? It can be done with ContentProvider + database from what I have read, although that seems like a bit too much for my needs. I have also considered an option to save the results to some cache file activities could read in onCreate, onResume etc and display the data. Are there any other convenient ways to share the data? (To make it more clear, the data aren't simple, so doing it through preferences etc is impossible.)
I was looking out for ways to share data between various activities that one may need to create for his applications . Using "Parcel" and Bundle one can do data exchange , but looks like this is a bit cumbersome process specifically if you have to share large array objects with too many fields.
As android.app.Application maintains global state for the application , we can use this class to store global data and access it across activities. Is this a good way ? Are there any implications on allocating large objects in the your class which extends from android.app.Application ?
I have an app with two activities.
Both activities among other functions have to perform the same calculation on data, so each activity include the same code to perform the calculation.
Is it possible to only have the similar code in a separate activity and be accessed by the other two activities instead of duplicating the code twice?
I think the following scenario is common, but I can't figure the way to implement it:
We have three Activities, and one database. We ask the user for an input to search in the database. The query should get none, one or may results.
If you get none you simple inform the user.
If you get only one, you show it in a new activity with the right view.
If you get many you show them in a list to let the user to chose the right one and then you pass that to the activity which with show the data in the case of one result only.
The problem is that, in order to know the number of results, you need to do the query (and get the cursor) in the first activity. And in the case you get more than one result you need to send the data (pass the cursor?)to the list acitivty. Doing the query again in the list activity can't be right, right?
I'm aware that you can share cursors by using a content provider, but as the activities are from the same application and the data is private (useless outside), don't see the point of making it avaliable to anyone else.
I read here around that you can crate a parcelable cursor and send it in bundle, but I'm not sure if that is the right use.
I have an Android application composed by several Activities. Most of them need to check whether an active network is available or not:
public boolean isNetworkAvailable() {
ConnectivityManager cm = (ConnectivityManager)
getSystemService(Context.CONNECTIVITY_SERVICE);
TelephonyManager tm = (TelephonyManager)
getSystemService(Context.TELEPHONY_SERVICE);
...
}
I would like to move that code to a helper class in order to avoid the need to write that code in every Activity, but calls to getSystemService are only allowed from an Activity. The other alternative is to move that code to a parent activity use inheritance but:
Every activity already extends from android.app.Activity
Some of my activities already extend from a common my.package.BaseActivity
(Activity <- BaseActivity <- XXXActivity)
What do you recommend in this case? Is there any other alternative?
I am working on a small android project where it is necessary to share some data amongst several activities and a service that runs in a separate process. I would just like to know what are my options in terms of sharing data? Application class? IPC? File-based? Broadcasts?
View 3 Replies View RelatedI'm in the middle of writing myself an app and have run into a problem concerning the use of the same SQLite database within multiple activities.
I have one activity that is used to input and store data and multiple activities that need to then read that data. Within the first activity, it has no problem inputting the data into the database, but when I go to have the other activity read the data, it tells me the database is empty. Obviously I'm doing something wrong in my handling of this shared database.
Right now, I have a DataHelper class that handles everything. In each activity, I create a DataHelper object which then calls the openOrCreateDatabase() method. I then close the database upon exiting the activity. Obviously this isn't the right way to do it.
So, my questions is, what is the correct way to set up an SQLite database in an Android application and then access it in multiple activities?
I have written my application logic in domain objects (to enable multiple user interfaces and porting to other platforms), and am now lookng at implementing Activities for the user interface.
Considering that each activity needs to serialise its state, what is the best way to ensure my domain objects are only serialised once?
I have two activities that both contain an identical context menu built programmatically using menu.add(int, int, int, CharSequence). They both use onCreateContextMenu and onContextItemSelected.
The first Activity contains a ListView, when the user long presses on an item the context menu appears for that item. The second Activity (a detail screen for each item in Activity 1) contains a button, when the user presses the button the context menu appears.
I'd like to share the code that creates the context menu between these activities. The only thing these activities share is the context menu, so it seems like a bit of overkill to create a superclass (e.g., ActivityOne extends ContextMenuActivity) that defines onCreateContextMenu and onContextItemSelected methods.
Is there a better way of sharing these methods between activities?
I need to be able to use one object in multiple activities within my app, and it needs to be the SAME object. What is the best way to do this?
I have tried making the object "public static" so it can be accessed by other activities but for some reason this just isn't cutting it. Are there any other ways of doing this?
I have an Object that I need to be able to pass between Activites. It implements Parcelable and I've written all the code related to that. The problem is that one of the properties of the Object is a Drawable - and really needs to be. Unfortunately, Drawable is neither Parcelable or Serializable. I don't understand how to pass it. The reason for having the Drawable is that I need to cache an Image that I've downloaded from the internet at runtime. I don't want to cache the images on the filesystem, since this would potentially end up using up a lot of space over time. I'm putting the image into a Drawable so that I can easily put it into an ImageView.
View 2 Replies View RelatedI currently have a service called ConnectionService. It instantiates a Connection object that gives me access to a controller of TCP.
I start the service from a splash screen activity, which sends and intent and starts my "main" activity once a connection has been established. In the "main" activity, I can access my Connection object and communicate with the controller. However, when I start a new activity from the "main" activity and bind to the service, I get a NullPointerException when I try to call methods in the ConnectionService.
I have been using SharedPreferences to share data between activities. But I would very much like to find a better way. I would simply like both Activity1 and Activity2 to share Object1. Activity1 will create Object1 and then start Activity2. What is the smartest way to give Activity2 a pointer to Object1?
To summarize: Activities don't have constructors! How do I send data to them from their parent activity?
I'm sharing some variables accross activities by using a class like this :
CODE:..........
Then I'm using these variables anywhere across my multiple activites with ...if (Globals.hint2_stockview_valuation == false) {....}
Pretty basic and it was working fine untill ...
I introduced some webview stuff like this:
CODE:...........
And here's the News_Webview.class:
CODE:............
The problem now is that, when it "comes back" from this Activity, it looks like my Globals variables have disappeared ?
if (Globals.hint2_stockview_valuation == false) {
fires an error :
06-23 12:14:03.443:
ERROR/AndroidRuntime(2611): Caused by:
java.lang.NullPointerException
2 Questions then:
Should I use something else than this "Global" class to share variables across activities ? Is it just bad practice to do this ?? I know that I can use the preferences but I thought it was quicker to do it this way (no need to "read" the preferences everytime I start a new activity ...Should I "get back" my savedInstanceState in some way when my activity returns from the News_Webview.class ?
I'm working on an application that requires non-serializable objects to be passed between Activities. The following page suggests using a HashMap of WeakReferences to accomplish this:
http://developer.android.com/guide/appendix/faq/framework.html
Is this solution safe? I know Activities are completely destroyed and recreated when the screen orientation changes. Couldn't those weakly referenced objects get GCed in the split second when the screen is rotated, since they wouldn't be referenced elsewhere at that point?
I like to know how can i clone a view object which is already there in the view hierarchy, so that it can be added to the same view hierarchy again.
View 1 Replies View RelatedCan two or more Android Activities open an sqlite3 database for write?
I have two Activities that need to insert data into the same sqlite database. When the second Activity calls SQLiteOpenHelper.getWriteableDatabase() an IllegalStateException is thrown with the message "SQLiteDatabase created and never closed".
I've been able to avoid the Exception by making my database object a singleton but I'm thinking there must be a better way.
I'm coding a very basic FTP client on top of my application and I have 2 activities. The first one is the file explorer and the second one is the image viewer. Once I click on the image filename on the explorer, I want to pass the connection to the other activity to handle extra stuff. Basically, I want to keep the same org.apache.commons.net.ftp.FTPClient object (which handles the connection) alive in-between the 2 activities. I know I can't pass an object inside an intent so I don't know what my best bets are.
View 1 Replies View RelatedThis is a followup to this post: http://stackoverflow.com/questions/3897176/findviewbyid-in-a-subclassed-surfaceview-throwing-runtimeexception Based on Romain Guy's feedback (which I'll accept shortly as it is a solution), I'd like to obtain the calling Activity from within the View, so that I can use it to obtain the desired Text View resource. I don't see any methods in View that return Activity. What is the proper way to do this? Or is there a better alternative for working with TextViews from within another View context. Basically, I am calling setContentView(R.layout.xxx) in onCreate() (as usual), so I don't really have a way to pass in references to additional TextViews unless I awkwardly retrieve the View after setContentView and then make calls on it.
View 1 Replies View RelatedWe see API for saying which is the next focusable view.. however during the event handling we want to set the focus to xyz view object pro grammatically . Is that possible.
View 3 Replies View RelatedIn the Tab2 of TabActivity in the APIDemo example, it has this method to create a View object for each tab. code...
Can you please tell me how can I create a View for each tab from an xml layout file? For example code...
I have a very simple requirement. I have a View object, lets say an ImageView object. I want to move this ImageView object in a circle.
More specifically, I want to move it along an arc, which is not a complete circle. I found in Android Documentation that comes with SDK that we can create a path from an arc but it does not mention how to use this path to make an animation that goes along that path.
Please note that I dont want to rotate the image. I have to move it in a circular path.
I am working on developing several individual android applications. We had created common UI Layout View XMLs, classes and resources. I would like to share these common layout xml, classes and resources across all of my android applications. I dont want to duplicate them in my applications. Is there any easy way to do this?
View 5 Replies View RelatedI have a Adapter View derived class (say GridLayout) in which I arrange views in a grid. When items in the grid exceed the height of the GridLayout( or screen) I want a scrollbar to appear. I have handled scrolling in onTouchEvent. But the problem is the scrollbars don't appear. I have set the vertical scrollbar to be enabled, but no use. The docs say the scrollbar appears every time the scrollTo or scrollBy methods are called.
View 2 Replies View RelatedI think this is a pretty simple question but I'm having trouble finding the answer out there.I'm developing an android application (currently developing against v1.5 API) and one of the activities use a ListView. I want to be able to set the properties of each List Item based on the state of an in memory object rather than the state of the view or list item.Here is a simple example....say I have a Person class who's public members are defined as follows. Code...
View 1 Replies View RelatedThis subject originates here: http://groups.google.com/group/android-beginners/browse_thread/thread...
To sum up:
When I click on an item in the ListView, the background color that gets changed is not that of the clicked item but instead of the other item in the opposite side relative to the middle item:
1 <-- I click here 2 3 <-- Acts as a mirror 4 5 <-- This is the one that gets changed
1 2 <-- This is the one that gets changed 3 <-- Acts as a mirror 4 <-- I click here 5
This problem persists even when I use CheckedTextView like what is suggested in the post.
I use the latest stable SDK.
This problem occurs when the target platform is Android 1.6, 2.0 or 2.0.1.
The problem does not occur when the target platform is Android 1.1 or 1.5.
However, the problem will also occur when the program is compiled for 1.5 and run in 2.0.1.
The simple problematic code can be found here: [url]
There I also put the screenshots showing the problem: demo01.png: I click an item. demo02.png: the clicked item doesn't get changed but the reflective item does.
Is this a bug in newer Android platforms?
If it is intended, what is the reason and could you please show me how I should fix my code?
I want to get the current focus view in my Service to check the view is a EditText and append some texts in it (for all EditTexts, not only in my application).
I found some methods to do this, like Activity.getCurrentFocus() and Windows.getCurrentFocus(). But these methods are used in a Activity.
How can I use these methods in a Service? Or is there another way to do?