CWAC SackOfViewsAdapter: Just the Views, Only the Views
ListView in Android supports header and footer views -- views that do not belong to the underlying adapter but otherwise show up in the list and scroll along with the contents. However, they only work if you have not yet set your own adapter and are therefore not terribly flexible.
The SackOfViewsAdapter is another way of approaching this. Here, you provide the Views that make up the rows, and the adapter feeds them to Android as if they were newly created.
The SackOfViewsAdapter is designed to be subclassed, mostly to determine how isEnabled() behaves, so you can control which of those views are selectable and which simply scroll with the list.
While standalone, this is not terribly useful, in conjunction with other adapters, perhaps other ones in the CWAC collection, it has greater benefit.
This Android library project is available as a JAR or as an artifact for use with Gradle. To use that, add the following blocks to your build.gradle file:
repositories {
maven {
url "https://s3.amazonaws.com/repo.commonsware.com"
}
}
dependencies {
compile 'com.commonsware.cwac:sacklist:1.0.3'
}
Or, if you cannot use SSL, use http://repo.commonsware.com for the repository URL.
NOTE: The JAR name, as of v1.0.1, has a cwac- prefix, to help distinguish it from other JARs.
Usage
You can use SackOfViewsAdapter directly or subclass it. The latter is needed to support on-demand row creation or controlling which rows are/are not enabled.
Constructors
SackOfViewsAdapter either takes a count or a List of View objects as parameters. In the first case, the count indicates how many total rows there will be. If you choose to pass in a List, and you want to add to it later on, make sure it is a mutable list (e.g., created by new ArrayList<View>()).
Defining Views at Runtime
If you pass in just a count of rows in the constructor, you need to extend SackOfViewsAdapter and override newView(), to return a row View given a position and the ViewGroup that is the row's parent (e.g., a ListView). SackOfViewsAdapter will then hang onto that row and return it to Android whenever that position is requested.
If you pass in a List of View objects in the constructor, some of those positions in the list can be null. In that case, you again have to extend SackOfViewsAdapter and override newView(), but you will only be called for those rows initially defined as null.
Other Methods to Override
You are welcome to override other methods as well, since this is just an Adapter. In particular, if all rows are not enabled for selection, you will want to override isEnabled() and return true or false as needed to indicate which rows are selectable and which are not (e.g., header rows).
Miscellany
You can call hasView() on a SackOfViewsAdapter to determine if it contains a certain View or not.
JavaDocs
JavaDocs are available for your JavaDocing pleasure.
Dependencies
None at present.
This project should work on API Level 4 and higher, except for any portions that may be noted otherwise in this document. Please report bugs if you find features that do not work on API Level 4 and are not noted as requiring a higher version.
Version
This is version v1.0.3 of this module.
Demo
In the demo/ sub-project you will find a sample activity that demonstrates the use of SackOfViewsAdapter.
License
The code in this project is licensed under the Apache Software License 2.0, per the terms of the included LICENSE file.
Questions
If you have questions regarding the use of this code, please post a question on Stack Overflow tagged with commonsware-cwac and android after searching to see if there already is an answer. Be sure to indicate what CWAC module you are having issues with, and be sure to include source code and stack traces if you are encountering crashes.
If you have encountered what is clearly a bug, please post an issue. Be certain to include complete steps for reproducing the issue. The contribution guidelines provide some suggestions for how to create a bug report that will get the problem fixed the fastest.
You are also welcome to join the CommonsWare Community and post questions and ideas to the CWAC category.
Do not ask for help via social media.
Release Notes
- v1.0.3: reorganized project into Android Studio-standard structure
- v1.0.2: updated Gradle files for Android Studio 1.0 and new publishing system
- v1.0.1: updated Gradle files and manifest for compatibility, added
cwac-prefix to JAR - v1.0.0: migrated to Gradle and published AAR
- v0.4.0: added
hasView() - v0.3.1: fixed copy-and-paste error in build.xml
- v0.3.0: converted to Android library project