I'd like to be able to loop through a list of xml layout files instead of having to specify a particular one in the setContentView argument.
Obviously the types are incorrect, but something like:
ArrayList<String> pages = new ArrayList<String>();
//(Where each of the xml pages are stored like R.layout.page1, R.layout.page2, etc)
setContentView(pages.get(0));
Is this possible somehow?
You should use the ViewFlipper widget instead. Here is an example.
It is cleaner to manage the content views and their children widgets this way.
Anyway, the resource IDs can be obtained from names using the Resources.getIdentifier method.
Yes. it's possible. But two notes:
The ids are ints, not Strings.
You need to manage the views inside them properly.
In an application I have created I use the following code to set the image button to a particular resource:
imgBtnCard.setImageResource(this.getResources()
.getIdentifier("com.twp.cptshitface:drawable/" +
cardType + cardDetails[1] , null, null));
I would say that this is what you are looking for:
int resLayoutId = this.getResources().
getIdentifier("your.package.namespace:layout/" +
pages.get(0), null, null);
setContentView(resLayoutId);
// where pages.get(0) returns a string such as "main2"
I've quickly tested this code in the onCreateMethod.
remember to clean your project if you add more layouts and/or resources so the id's are updated!
Related
I want to give ids to multiple views created programmatically and each id to be a specific integer based on my own logic. Consider the following example:
I have M colors defined in a sequential way, e.g. using enum, or using an array to put M color values. (Which implementation/structure to use is part of the puzzle and suggestions need to be provided for this as well, in order to achieve the final goal described below.)
Create N instances of a custom Class and store them in a sequential way too (e.g. an array of N elements). This custom Class will just have a member mColor where a color for the specific instance will be stored.
Create (programmatically always) N RadioGroups with M RadioButtons for each RadioGroup.
The goal is when user clicks the j-th RadioButton of the i-th RadioGroup, then the i-th instance will use as background color the j-th color.
So, I would like to do something like this when OnCheckedChanged event occurs for a RadioGroup:
public void onCheckedChanged(RadioGroup group, int checkedId) {
int i = group.getId();
/*j variable is not actually needed here, but is used for concistency
with the description above.*/
int j = checkedId;
/*assume for simplicity that an array of N elements is used to store
the N CustomCLass instances and an array of M elements is used for
colors*/
customClassArray[i].setmColor(colorsArray[j]);
}
From the above, I think it is necessary that specific ids for the programmatically created RadioGroups and RadioButtons need to be set. If there is a way for this to be done, then code will be clear, optimized and no switch statements will be needed for N RadioGroups and M RadioButtons (for which, in any case, I have no clue about how it could be implemented too).
Which is the best way to achieve this, firstly with efficiency in mind and secondly, with clear code in mind?
Thank you in advance for any suggestions.
Edit: For clarification, I have read about setting my own ids by using View.setId(), but there are many resources on the web which are against this hardcoded approach (and I also vote against this if there is another way) and many of them suggest using xml resource to put your ids. However, as I said earlier, I think this is not what I want in order to achieve my goal.
Example links suggesting this approach: https://code.google.com/p/android/issues/detail?id=75081 or also How to set Id of dynamic created layout?.
Also, this approach is the suggested one in the android developer documentation: http://developer.android.com/guide/topics/resources/more-resources.html#Id
Lastly, I have also read this: What is the main purpose of setTag() getTag() methods of View? which explains the purpose of Tags and the use of setTag()/getTag() methods. This may be the best approach I've found so far for what I need. However, it surely introduces more complicated, unsupportable code. In any case, the right way, I think, has to be connected with ids, whose purpose is to uniquely identify views, rather than tags.
As you are creating RadioGroups and RadioButtons from java, I suggest to create a map and use radiobutton reference as key and instance-color combination as value. assign a single checkChangedListener to all your radioButtons and process the event as follows
#Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
colorInstanceCombo = map.get(buttonView);
//use colorInstanceCombo to do your work
}
assigning ids dynamically can cause problems as id is an integer and your assigned ids may cause conflict with system assigned ids to other components.
I have created controls in android pragmatically by reading an xml
For Example
CheckBox checkbox = new CheckBox(this);
checkbox.setText("Text");
I would like to get the values in the control at a later stage dynamically
View view = this.findViewById(resId);
bool checked = ((CheckBox)view).isChecked();
How do I "resId" for the control created pragmatically.
I tried to use checkbox.getId() but it is returning 0
You better keep reference to your control and use it to set values.
Map<String, CheckBox > checkBoxes = new HashMap<String, CheckBox >();
...
checkBoxes.put("checkBox1", new CheckBox(this));
...
CheckBox checkbox = checkBoxes.get("checkBox1");
But if you really want id you can set your custom id via setId method as #Merlevede suggested but let android generate the id to avoid conflicts. Create a xml resource item:
<item type="id" name="your_super_puper_id"/>
And then use it: xxx.setId(R.id.your_super_puper_id)
To find Views you can use tagging. Using setTag method you can attach any object to a view and then use that object to find view via findViewWithTag method.
String superPuperStringId = "checkBox1";
someView.setTag(superPuperStringId);
...
view = someViewGroup.findViewWithTag(superPuperStringId);
Also you can create your checkbox via xml and assign id there.
You can set a custom ID using checkbox.setID(25) (for example), you need to provide a unique ID. The problem that you may encounter is that there's and ID collision with some other control (if you're also using a layout XML), because the IDs are generated automatically.
I would suggest keeping your checkbox variable as a member of your class, so that yo can access it later on.
As the question states I simply want to add more than one tag to an XML View. For example, say I want to set an array of strings AND a separate string from my resources. I know how to do them individually but I want to know if there's a way of attaching more than one tag to a view directly within the XML code.
Edit:
My plan was to have a LinearLayout (l#1) that contained a dynamic amount of of a different LinearLayout (l#2) and within that View there would be a Spinner and an EditText. I need one tag for the hint of the EditText and the other for the array of strings to populate the Spinner. In the entire layout there are a multiple l#1 each using l#2 to populate it dynamically and each needing different hints and string arrays based on what they are used for.
My next idea was to add a integer as a tag to represent l#1 and and use a Switch/Case block in my code to populate the children of l#2 with the right hints and string arrays.
I don't think this is possible in XML, but in code what you could do is create a custom object which holds the strings you require and set that as the tag.
class CustomTagObject {
public List<Strings> strings;
public String myString;
}
Then later
CustomTagObject tagObj = new CustomTagObject();
tagObj.strings = new ArrayList<Strings>("String 1", "String 2");
tagObj.myString = "String from resources";
view.setTag(tagObj);
If you explain why you want to hold these items as the tag, I may be able to help you find an alternative approach?
Above solution works, but the usage is wrong(it will add extra overhead on your end to manage the key/value map).
The better way to achieve above is to use an overloaded method of setTag which allows you to specify id associated with the value.
Method signature:
public void setTag(int key, Object tag)
i would like to ask a lot of questions about how this whole id system works in android. I looked up the View documentation, but the description was too shallow for my taste.
Is there a pattern, how the IDE (Eclipse/Netbeans) generates the ids
when i use android:id="#+id/..."? Or is it completely random?
If i set ids programmatically, then will it be found by the Context
classes findViewById() function?
If the answer for the previous question is yes, then if i want to
create a large amount of Views, but i want them to have distinct ids
for later identification, then wich one is better to use? (To answer
this question, it would be really useful to know the answer for the
first two)
For example generating random ids in the largest possible range:
Random random = new Random();
for(int i=0; i<100; i++)
{
View view = new View(someContext);
view.setId(random.nextInt(Integer.MAX_VALUE));
}
Or setting the ids in some sort of order, for example:
final int addToId = 5670;
for(int i=0; i<100; i++)
{
View view = new View(someContext);
view.setId(i+addToId);
}
Also i would like to know, what happens, when you use a
LayoutInflater for example to populate a ListView using a
pre-defined xml layout for every item in the list. Then you get your
sub-views in the getView() function by the findViewById(). So i
assume, that all the identical Views across your listitems have the
same id. If so, then is it a good practice to use the tag
attribute to distinguish the items in an inflated layout?
Any clear explanation for these question would be highly appreciated!
#+id/.... creates an id value that lives within the applications namespace. Contrast this with #android:id/.... which lives in the android namespace.
When you set the id in code and add the view element to the layout it will then become available to access through the code. You won't be able to reference it from the xml
Not sure you want to be using random to generate your ids? think sequential would be better but even then what is the point of a random id? How do you know which view you are referring to?
Definitely use the tag option and look to use the ViewHolder pattern for smoother list scrolling. You could add the id to the view holder class if you need access to it but it would be available anyway through the data set being used to populate the list. A quick search will give you plenty of examples for this.
On subclasses of View there is a getTag() method, which returns the android:tag attribute's value from .xml.
I would like the same for a MenuItem... is it okay to just cast it to a View?
Because item elements also allow a tag attribute in .xml...
Update: My goal with this is setting a tag in .xml, i.e. "notranslate", and querying it at runtime (we localize by hand at runtime, don't ask...)
It is always alright to cast, however, casting any Interface cannot be checked at compile time, only runtime. This is normally the reason many do not recommend casting an Interface that you have no control over. Having the proper error checking code is the best way to insure that such a cast does not break your code.
For the casting, it doesn't really matter whether the MenuItem is an Interface or a View, but the object it references must be one of View's subclasses, if not a View itself. If you are going to cast it, try the cast and catch a ClassCastException just in case as this is the error that will be thrown in runtime.
Another option is that since the MenuItem is simply an interface, you can easily just create a View subclass that utilizes MenuItem allowing you to do the cast. If you are doing a custom ContextMenu as many launchers do, then chances are your answer is nearly complete.
Hope this helps,
FuzzicalLogic
MenuItem is an interface. Any class can implement this interface and so it will not always be safe to cast the MenuItem to a View. You can use the "instanceOf" operator to test to see if the object that implements the MenuItem interface is indeed a View or not.
I understand that you want to define a flag in the XML definition of the menu and then at run time interrogate that flag to make a programmatic decision.
The Menu Resource Documentation records what attributes can be set in the XML. You can consider using (abusing) one of those settings such as the "android:alphabeticShortcut" to encode the flag and use the MenuItem::getAlphabeticShortcut() method to get the value. This does not require casting - it just uses the existing fields in the MenuItem XML construct/class for your own purposes.
Perhaps a less hacky way to do this is to keep a simple table in a separate assets file that lists the menu item identifiers and the special behavior associated with that identifier such as to translate or not to translate.
Alternatively create a simple class that has a table with this configuration information hard coded using the logical "#[+][package:]id/resource_name" resource identifier as the keys to the table. While this doesn't keep it all in one place (in the XML) it does it in a manner that is not encoding information in unused attributes, or relying on the ids not changing. The "table" could be implemented as a static method with an embedded switch statement allowing code such as "if (TranslationTable.shouldTranslate(menuItem.getItemId())) { do translation }"
I had a similar problem in that I wanted to associate some arbitrary data with each menu item so that I could handle menu items in a generic way without having to use hardcoded checks for individual item ids in code.
What I did was for a particular menu item (e.g. #+id/foo) There was an a TypedArray that was defined using the same name as the menu item ID. You could do this with other types of resources as well.
So to do the association, you get the resouce entry name (foo in my example) and then use that to look up the id of the other resource of a different type (#array/foo in my example).
In my handler for menu I had code like this:
Resources resources = getResources();
String name = resources.getResourceEntryName(item.getItemId());
int id = resources.getIdentifier(name, "array", "com.example");
if(id != 0)
{
TypedArray data = resources.obtainTypedArray(id);
// Use the typed array to get associated data
}
EDIT:
Actually it is even easier than that. There is nothing special about the ids on menu items other than you don't want multiple menu items with the same id. The id does not have to be of the form #+id/foo. It can actually also refer to other resources. So in my example above, instead of having the menu have an id of #+id/foo and using the resource manager to use that to find #array/foo, I changed to actually have the menu item have the id of #array/foo.
Now in my onOptionsItemSelected I have this:
Resources resources = getResources();
if("array".equals(resources.getResourceTypeName(item.getItemId())))
{
TypedArray data = resources.obtainTypedArray(item.getItemId());
// Use the typed array
}