The component name is set by setComponent setClass or setClass Name and read by getComponent Action

A string naming the action to be performed — or, in the case of broadcast intents, the action that took place and is being reported. The Intent class defines a number of action constants, including these:

Data

The URI of the data to be acted on and the MIME type of that data. Different actions are paired with different kinds of data specifications. For example, if the action field is ACTION EDIT, the data field would contain the URI of the document to be displayed for editing. If the action is ACTION_CALL, the data field would be a tel: URI with the number to call. Similarly, if the action is ACTION_VIEW and the data field is an http: URI, the receiving activity would be called upon to download and display whatever data the URI refers to.

When matching an intent to a component that is capable of handling the data, it's often important to know the type of data (its MIME type) in addition to its URI. For example, a component able to display image data should not be called upon to play an audio file.

®In many cases, the data type can be inferred from the URI — particularly content: URIs, which indicate that the data is located on the device and controlled by a content provider (see the separate discussion on content providers). But the type can also be explicitly set in the Intent object. The setData() method specifies data only as a URI, setType() specifies it only as a MIME type, and setDataAndType() specifies it as both a URI and a MIME type. The URI is read by getData( ) and the type by getType() .

Category

A string containing additional information about the kind of component that should handle the intent. Any number of category descriptions can be placed in an Intent object. As it does for actions, the Intent class defines several category constants, including these:

Constant

Meaning

CATEGORY BROWSABLE

The target activity can be safely invoked by the browser to display data referenced by a link — for example, an image or an e-mail message.

CATEGORY GADGET

The activity can be embedded inside of another activity that hosts gadgets.

CATEGORY HOME

The activity displays the home screen, the first screen the user sees when the device is turned on or when the HOME key is pressed.

CATEGORY LAUNCHER

The activity can be the initial activity of a task and is listed in the top-level application launcher.

CATEGORY PREFERENCE

The target activity is a preference panel.

See the Intent class description for the full list of categories.

The addCategory() method places a category in an Intent object, removeCategory() deletes a category previously added, and getCategories() gets the set of all categories currently in the object.

Extras

Key-value pairs for additional information that should be delivered to the component handling the intent. Just as some actions are paired with particular kinds of data URIs, some are paired with particular extras. For example, an ACTION TIMEZONE CHANGED intent has a "time-zone" extra that identifies the new time zone, and ACTION HEADSET PLUG has a "state" extra indicating whether the headset is now plugged in or unplugged, as well as a "name" extra for the type of headset. If you were to invent a SHOW COLOR action, the color value would be set in an extra key-value pair.

The Intent object has a series of put...() methods for inserting various types of extra data and a similar set of get...() methods for reading the data. These methods parallel those for Bundle objects. In fact, the extras can be installed and read as a Bundle using the

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  • melissa thomson
    How to receive a broadcast using the setclassname?
    6 years ago

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