Intent - StansAssets/com.stansassets.android-native GitHub Wiki

An intent is an abstract description of an operation to be performed. It can be used with startActivity to launch an Activity

An Intent provides a facility for performing late runtime binding between the code in different applications. Its most significant use is in the launching of activities, where it can be thought of as the glue between activities. It is basically a passive data structure holding an abstract description of an action to be performed.

Intent Structure

The primary pieces of information in an intent are:

• action -- The general action to be performed, such as ACTION_VIEW, ACTION_EDIT, ACTION_MAIN, etc.

• data -- The data to operate on, such as a person record in the contacts database, expressed as a Uri.

Some examples of action/data pairs are:

• ACTION_VIEW content://contacts/people/1 -- Display information about the person whose identifier is "1".

• ACTION_DIAL content://contacts/people/1 -- Display the phone dialer with the person filled in.

• ACTION_VIEW tel:123 -- Display the phone dialer with the given number filled in. Note how the VIEW action does what is considered the most reasonable thing for a particular URI.

• ACTION_DIAL tel:123 -- Display the phone dialer with the given number filled in.

• ACTION_EDIT content://contacts/people/1 -- Edit information about the person whose identifier is "1".

• ACTION_VIEW content://contacts/people/ -- Display a list of people, which the user can browse through. This example is a typical top-level entry into the Contacts application, showing you the list of people. Selecting a particular person to view would result in a new intent { ACTION_VIEW content://contacts/people/N } being used to start an activity to display that person.

In addition to these primary attributes, there are a number of secondary attributes that you can also include with an intent:

• category -- Gives additional information about the action to execute. For example, CATEGORY_LAUNCHER means it should appear in the Launcher as a top-level application, while CATEGORY_ALTERNATIVE means it should be included in a list of alternative actions the user can perform on a piece of data.

• type -- Specifies an explicit type (a MIME type) of the intent data. Normally the type is inferred from the data itself. By setting this attribute, you disable that evaluation and force an explicit type.

• component -- Specifies an explicit name of a component class to use for the intent. Normally this is determined by looking at the other information in the intent (the action, data/type, and categories) and matching that with a component that can handle it. If this attribute is set then none of the evaluation is performed, and this component is used exactly as is. By specifying this attribute, all of the other Intent attributes become optional.

• extras -- This is a Bundle of any additional information. This can be used to provide extended information to the component. For example, if we have a action to send an e-mail message, we could also include extra pieces of data here to supply a subject, body, etc.

Here are some examples of other operations you can specify as intents using these additional parameters:

• ACTION_MAIN with category CATEGORY_HOME -- Launch the home screen.

• ACTION_GET_CONTENT with MIME type vnd.android.cursor.item/phone -- Display the list of people's phone numbers, allowing the user to browse through them and pick one and return it to the parent activity.

• ACTION_GET_CONTENT with MIME type / and category CATEGORY_OPENABLE -- Display all pickers for data that can be opened with ContentResolver.openInputStream(), allowing the user to pick one of them and then some data inside of it and returning the resulting URI to the caller. This can be used, for example, in an e-mail application to allow the user to pick some data to include as an attachment.

There are a variety of standard Intent action and category constants defined in the Intent class, but applications can also define their own. These strings use Java-style scoping, to ensure they are unique -- for example, the standard ACTION_VIEW is called "android.intent.action.VIEW".

Put together, the set of actions, data types, categories, and extra data defines a language for the system allowing for the expression of phrases such as "call john smith's cell". As applications are added to the system, they can extend this language by adding new actions, types, and categories, or they can modify the behavior of existing phrases by supplying their own activities that handle them.

The AN_Intent class is base on Google Intent object. Let us know if you need more API related to Intent. Feel free to contact us at https://stansassets.com/