Develop Reference

Best way to store Resource id in Database on Android

In my app i want to be able to store resource id of some icons in database. I suppose it is not save to do, cause in the later stages (application upgrades) i may want to add new icons to the app, so all id's may change? What is the best practice to store resource in case i do not want to store icons as blobs?
As an example, let's say i have a game 1.0, where i let user to choose an avatar for his character from a list of avatars. I want to store this avatars id in DB and be sure that if i add more avatars in game 1.1 - user will still see his choice.

The best way (in my opinion) is to store the resource entry name.
String iconName = getResources().getResourceEntryName(R.drawable.your_icon);
So your SQLite database column where you want to store the icon will have type TEXT. You're right that storing resource IDs is a bad practice because they're recreated when you compile the app, so you can't rely on them not changing (I learned this the hard way, all my app's icons got messed up).
To get the resource ID from the String when you need it, call
int resID = getResources().getIdentifier(iconName, "drawable", getPackageName());
Note that both getResources() and getPackageName() are methods from Context, so you need to have reference to your application/activity Context to be able to call these methods.

Android: image ID in layout directory

I have 100 images in my application of different cities and I want to divide these pictures in different groups, lets say in evening, morning, sunny, raining etc…
We know that when we call an image from layout folder by calling R.layout.image_1, android generates integer number for each image
For example:
R.layout.image_1 (223344), R.layout.image_2 (556677),
R.layout.image_3 (778899),
I can create one table having evening, morning fields and I can assign group of pictures to each of them with integer IDs which are (223344,556677) and I can call evening or morning group and i can display all images related to these group.
My question is: Does Android generate same number every time. Are these numbers are fixed? When ever the application runs.
If its true then upper idea will work for me. If this idea is incorrect then kindly guide me what is the decent approach to handle hundreds of PNGs in application.

Those numbers are not fixed. R will be regenerated and can have completely different numbers if you change something. That is why when comparing ids, you compare by the name instead.
Eg instead of
if (i == 223344)
do
if (i == R.layout.image_1)
Since R.layout.image_1 references the integer id, the name won't change (unless you change the layout xml name.
If you want to get a resource id dynamically (by a string representing the name), you should have a look at this method - Resources#getIdentifier().

First of all we generally put images in the drawable folder.
Does Android generate same number every time?
No.
Are these numbers fixed whenever the application runs?
Yes.
In fact, once your project is built, the ids will remain the same for that same build.
In other words for a certain generated APK file, the ids won't change.
So how can you take advantage of that to group your resources?
You could have a static int array that holds the ids:
public static final int[] IMAGES_MORNING = {R.drawable.morning0, R.drawable.morning1, etc};
public static final int[] IMAGES_EVENING = {R.drawable.evening0, R.drawable.evening1, etc};
Although a more structured method would be to store them in a database on your app's first launch.
Or you could use what A--C suggests:
For example to get all the ids of morning images
for(int i = 0; i < numberOfMorningImages ; i++){
int id = getResources().getIdentifier("morning" + i, "drawable", getPackageName());
// do something with the id
}

No, there's no guarantee that integers will be the same every time, so the solution you've described won't work. Unfortunately, there's no proper way to group drawables inside the res/drawable folder. As a workaround, you can store them inside the assets folder, where you can group them as you like. However, Android won't be able to handle different resolutions this way. The choice is up to you. Hope this helps.

Android - assign and retrieve ID's dynamically

I know how to assing ID's dynamically by invoking setID(). For the ID's to be unique, I used to utilize ids.xml and pass to setID() ID's from the pre-generated pool of ID's.
Question 1: Is there any way to assign ID's without utilizing the ids.xml since I cannot anticipate how many ID's I will need in runtime?
I tried to bypass the first issue presented in Question 1 by dynamically assigning each of which an id based on its label's hash (each label is unique), but there is no way to gaurantee that ID's won't be colliding with ID's auto generated in R.java.
Question 1.1: How the ID naming collision can be resolved?
Question 2: Assume I have the ID value of which I assign and generate dynamically. Since the aformentioned ID does not appear in R.id, findViewById() won't be applicable for retrieving the view. Hence, how can the view be retrieved when the ID is known?
Answer 2: You'd be able to retrieve the view by its corresponding ID only after onCreate() has returned control (terminated).

From API level 17 you can get a new id by calling
View.generateViewId()
Details here.

Is there any way to assign ID's without utilizing the ids.xml since I
cannot anticipate how many ID's I will need in runtime?
This guarantees that every view has a unique ID
for(int i =0 ; i < yourIDcount ; i++){
yourView.setId(i);
}
how can the view be retrieved when the ID is known?
View.findViewById(yourView.getId());
can be used to get your view's id, since every view has a unique Id you can get back the view you wanted..
The word dynamic means which is created at runtime, since you assign id in onCreate it is assigned as the views id, since onCreate is called only once an activity is created, you can make sure that the id you assigned stays intact...

Playing raw file based on String

I have a simple program where I generate random numbers, and use these to return an element from an array. Based on this array element, I want to play a sound file. For example: The random element that was returned was "Am". I now want to play the file "am.ogg". But you cant just throw a string in for the resourceId. Any ideas?

This seems to be duplicate of this thread (which by the way is also duplicate). Except for using this method you can also use reflection on the R class (second also not good option). The best option is the one in which the list of ids you will be interested in can be determined in the code. Basically you define map mapping every string to the corresponding R.id variable (int). However, I am not quite sure this will be your case.

Using text field with AdapterView

Is it possible to use AdapterView with text fields in android?
My query returns a set of values and for each I want to place that within a textfield, so that the user may edit the value.
Also, I want to click a button to create a new empty field, so that I may insert a new entry.
If you know of good example, then please let me know!
EDIT 1
I would prefer to use XML to define ui and I found this informations:
"In this case we create a new id called text1. The + after the # in the id string indicates that the id should be automatically created as a resource if it does not already exist, so we are defining text1 on the fly and then using it." Source http://developer.android.com/resources/tutorials/notepad/notepad-ex1.html
Will this + allow me to autocreate as many fields as needed? Is there a way I can generically specify the layout in XML and then create fields adhoc based on db response?
Many thanks,
Mith

Is it possible to use AdapterView with
text fields in android?
Yes. It will be complex for you (and possibly also for the user), so I would not recommend it unless you have a few months' Android programming experience, but it should work.
Also, I want to click a button to
create a new empty field, so that I
may insert a new entry.
That will get a little complicated.
Will this + allow me to autocreate as
many fields as needed?
No, that is not how you use ListAdapters for ListView rows.
Is there a way I can generically
specify the layout in XML and then
create fields adhoc based on db
response?
Use a CursorAdapter.
Here is a free excerpt from one of my books that describes creating custom adapter classes. Here is a sample project that shows creating a custom CursorAdapter to display the results of a database query.