By Android startActivityForResult() method, we can get result from another activity.
By the help of android startActivityForResult() method, we can send information from one activity to another and vice-versa. The android startActivityForResult method, requires a result from the second activity (activity to be invoked).
In such case, we need to override the onActivityResult method that is invoked automatically when second activity returns result.
Method Signature
There are two variants of startActivityForResult() method.
public void startActivityForResult (Intent intent, int requestCode)
public void startActivityForResult (Intent intent, int requestCode, Bundle options)
Example:
An Image capture from existing Camera Apps
A quick way to enable taking pictures or videos in your application without a lot of extra code is to use an Intent to invoke an existing Android camera application. A camera intent makes a request to capture a picture or video clip through an existing camera app and then returns control back to your application. This section shows you how to capture an image or video using this technique.The procedure for invoking a camera intent follows these general steps:
Compose a Camera Intent - Create an Intent that requests an image or video, using one of these intent types:
MediaStore.ACTION_IMAGE_CAPTURE - Intent action type for requesting an image from an existing camera application.
Start the Camera Intent - Use the startActivityForResult() method to execute the camera intent. After you start the intent, the Camera application user interface appears on the device screen and the user can take a picture or video.
Receive the Intent Result - Set up an onActivityResult() method in your application to receive the callback and data from the camera intent. When the user finishes taking a picture or video (or cancels the operation), the system calls this method.
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
private Uri fileUri;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// create Intent to take a picture and return control to the calling application
Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE);
fileUri = getOutputMediaFileUri(MEDIA_TYPE_IMAGE); // create a file to save the image
intent.putExtra(MediaStore.EXTRA_OUTPUT, fileUri); // set the image file name
// start the image capture Intent
startActivityForResult(intent, CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE);
}
When the startActivityForResult() method is executed, users see a camera application interface. After the user finishes taking a picture (or cancels the operation), the user interface returns to your application, and you must intercept the onActivityResult() method to receive the result of the intent and continue your application execution
Receiving camera intent result
Once you have constructed and executed an image or video camera intent, your application must be configured to receive the result of the intent. This section shows you how to intercept the callback from a camera intent so your application can do further processing of the captured image.
In order to receive the result of an intent, you must override the onActivityResult() in the activity that started the intent. The following example demonstrates how to override onActivityResult() to capture the result of the image camera intent camera intent examples shown in the previous sections.
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
// Image captured and saved to fileUri specified in the Intent
Toast.makeText(this, "Image saved to:\n" +
data.getData(), Toast.LENGTH_LONG).show();
} else if (resultCode == RESULT_CANCELED) {
// User cancelled the image capture
} else {
// Image capture failed, advise user
}
}
}
Note: Any existing app which have hardware uses you need to add hardware uses and permission must.
Manifest Declarations
Before starting development on your application with the Camera API, you should make sure your manifest has the appropriate declarations to allow use of camera hardware and other related features.Camera Permission - Your application must request permission to use a device camera.
<uses-permission android:name="android.permission.CAMERA" />
Camera Features - Your application must also declare use of camera features, for example:
<uses-feature android:name="android.hardware.camera" />
