Lesson Plan: Unit - 01
Subject: P15A2AAD - Android Application Development
Topic of Study: Intent and It's Types
Grade/Level: Master of Computer Applications
Objective: To understand the parameters of Intent & it's types with demonstration
Time Allotment: 55 Minutes
- Intent
- An intent is an abstract description of an operation to be performed.
- An Intent provides a facility for performing late run time 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.
- Intents are the standard messaging mechanism in Android that expresses the user’s intention to perform some work.
- They allow you to interact with other components defined by you or by the Android operating system.
- Example:
- Broadcast a message
- Start the camera
- Start a service
- Launch an activity
- Display a web page or a list of contacts
- Dial a phone number or answer a phone call
- An Intent object is a bundle of information which is used by the component that receives the intent.
- They are used in both ways
- 1) by you to call a component
- 2)by the system to notify you of some event.
- Where Intent can be used?
- Context.startActivity()
- The Intent object is passed to this method to launch a new activity or get an existing activity to do something new.
- Context.startService()
- The Intent object is passed to this method to initiate a service or deliver new instructions to an ongoing service.
- Context.sendBroadcast()
- The Intent object is passed to this method to deliver the message to all interested broadcast receivers.
- The logical workflow of creating an intent is usually as follows:
- a. Create the Intent
- b. Add Intent options-> Ex. what type of intent we are sending to the OS or any attributes associated with that intent, such as a text string or something being passed along with the intent.
- c. RUN the Intent
- Intent Structure
- The primary pieces of information in an intent are:
- action
- It is mandatory part of the Intent object.
- The general action to be performed, such as ACTION_VIEW, ACTION_EDIT, ACTION_MAIN, etc.
- Exa.
- ACTION_VIEW content://contacts/people/1 -- Display information about the person whose identifier is "1".
- ACTION_EDIT content://contacts/people/1 -- Edit information about the person whose identifier is "1".
- ACTION_VIEW tel:123 -- Display the phone dialer with the given number filled in
- data
- It is adds a data specification to an intent filter.
- The data to operate on, such as a person record in the contacts database, expressed as a Uri.
- There are a number of secondary attributes that you can also include with an intent:
- category
- It is an optional part of Intent object.
- Gives additional information about the action to execute.
- For example, CATEGORY_LAUNCHER means it should appear in the Launcher as a top-level application.
- type
- Specifies an explicit type (a MIME type) of the intent data.
- Normally the type is inferred from the data itself.
- component
- It is name of optional field representing either Activity, Service or Broadcast Receiver.
- 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.
- extras
- It is in key-value pairs for additional information.
- 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.
- Intent Types or Intent Resolution
- There are two primary forms of intents you will use.
- Explicit Intents
- Explicit intent going to be connected internal world of application.
- Exa. To connect one activity to another activity.
- It have specified a component (via setComponent(ComponentName) or setClass(Context, Class)), which provides the exact class to be run.
- Often these will not include any other information, simply being a way for an application to launch various internal activities it has as the user interacts with the application.
- Implicit Intents
- These intents do not name a target and the field for the component name is left blank.
- Implicit intents are often used to activate components in other applications.
- have not specified a component;
- instead, they must include enough information for the system to determine which of the available components is best to run for that intent.
- Exa.
- Pending Intents
- ?
- Sticky Intents
- ?
