When `android:autoVerify="true"` is present in at least one of your app's intent
filters, installing your app on a device that runs Android 6.0 (API level 23) or
higher causes the system to automatically verify the hosts associated with the
URLs in your app's intent filters. On Android 12 and higher, you
can also [invoke the verification process manually](https://developer.android.com/training/app-links/verify-applinks#manual-verification) to
test the verification logic.

## Auto verification

The system's auto-verification involves the following:

1. The system inspects all intent filters that include any of the following:
   - Action: `android.intent.action.VIEW`
   - Categories: `android.intent.category.BROWSABLE` and `android.intent.category.DEFAULT`
   - Data scheme: `http` or `https`
2. For each unique host name found in the above intent filters, Android queries the corresponding websites for the Digital Asset Links file at `https:///.well-known/assetlinks.json`.

| **Note:** On Android 11 (API level 30) and lower, the system establishes your app as the default handler for the specified URL patterns only if it finds a matching Digital Asset Links file for *all* hosts in the manifest.

After you have confirmed the list of websites to associate with your app, and
you have confirmed that the hosted JSON file is valid, install the app on your
device. Wait at least 20 seconds for the asynchronous verification process to
complete. Use the following command to check whether the system verified your
app and set the correct link handling policies:  

```
adb shell am start -a android.intent.action.VIEW \
    -c android.intent.category.BROWSABLE \
    -d "http://domain.name:optional_port"
```

### Manual verification

Starting in Android 12, you can manually invoke domain
verification for an app that's installed on a device. You can perform this
process regardless of whether your app targets Android 12.

#### Establish an internet connection

To perform domain verification, your test device must be connected to the
internet.

#### Support the updated domain verification process

If your app targets Android 12 or higher, the system uses the
updated domain verification process automatically.

Otherwise, you can manually enable the updated verification process. To do so,
run the following command in a terminal window:  

```
adb shell am compat enable 175408749 PACKAGE_NAME
```

#### Reset the state of Android App Links on a device

Before you manually invoke domain verification on a device, you must reset the
state of Android App Links on the test device. To do so, run the following
command in a terminal window:  

```
adb shell pm set-app-links --package PACKAGE_NAME 0 all
```

This command puts the device in the same state that it's in before the user
chooses default apps for any domains.

#### Invoke the domain verification process

After you reset the state of Android App Links on a device, you can perform the
verification itself. To do so, run the following command in a terminal window:  

```
adb shell pm verify-app-links --re-verify PACKAGE_NAME
```
| **Note:** Before you review the results of this command, wait a few minutes for the verification agent to finish the requests related to domain verification.

#### Review the verification results

After allowing some time for the verification agent to finish its requests,
review the verification results. To do so, run the following command:  

```
adb shell pm get-app-links PACKAGE_NAME
```

The output of this command is similar to the following:  

```
com.example.pkg:
    ID: 01234567-89ab-cdef-0123-456789abcdef
    Signatures: [***]
    Domain verification state:
      example.com: verified
      sub.example.com: legacy_failure
      example.net: verified
      example.org: 1026
```

The domains that successfully pass verification have a domain verification state
of `verified`. Any other state indicates that the domain verification couldn't
be performed. In particular, a state of `none` indicates that the verification
agent might not have completed the verification process yet.

The following list shows the possible return values that domain verification can
return for a given domain:

`none`
:   Nothing has been recorded for this domain. Wait a few more minutes for the
    verification agent to finish the requests related to domain verification, then
    [invoke the domain verification process](https://developer.android.com/training/app-links/verify-applinks#invoke-domain-verification) again.

`verified`
:   The domain is successfully verified for the declaring app.

`approved`
:   The domain was force-approved, usually by executing a shell command.

`denied`
:   The domain was force-denied, usually by executing a shell command.

`migrated`
:   The system preserved the result of a previous process that used legacy domain
    verification.

`restored`
:   The domain was approved after the user performed a data restore. It's assumed
    that the domain was previously verified.

`legacy_failure`
:   The domain was rejected by a legacy verifier. The specific failure reason is
    unknown.

`system_configured`
:   The domain was approved automatically by the device configuration.

Error code of `1024` or greater

:   Custom error code that's specific to the device's verifier.

    Double-check that you have [established a network
    connection](https://developer.android.com/training/app-links/verify-applinks#establish-internet-connection), and [invoke the domain
    verification process](https://developer.android.com/training/app-links/verify-applinks#invoke-domain-verification) again.

## Request the user to associate your app with a domain

Another way for your app to get approved for a domain is to ask the user to
associate your app with that domain.
| **Note:** On a given device, only one app at a time can be associated with a particular domain. If another app is already verified for the domain, the user must first disassociate that other app with the domain before they can associate your app with the domain.

### Check whether your app is already approved for the domain

Before you prompt the user, check whether your app is the default handler for
the domains that you define in your `<intent-filter>` elements. You can query
the approval state using one of the following methods:

- The [`DomainVerificationManager`](https://developer.android.com/reference/android/content/pm/verify/domain/DomainVerificationManager) API (at runtime).
- A command-line program (during testing).

#### DomainVerificationManager

The following code snippet demonstrates how to use the
`DomainVerificationManager` API:  

### Kotlin

```kotlin
val context: Context = TODO("Your activity or fragment's Context")
val manager = context.getSystemService(DomainVerificationManager::class.java)
val userState = manager.getDomainVerificationUserState(context.packageName)

// Domains that have passed Android App Links verification.
val verifiedDomains = userState?.hostToStateMap
    ?.filterValues { it == DomainVerificationUserState.DOMAIN_STATE_VERIFIED }

// Domains that haven't passed Android App Links verification but that the user
// has associated with an app.
val selectedDomains = userState?.hostToStateMap
    ?.filterValues { it == DomainVerificationUserState.DOMAIN_STATE_SELECTED }

// All other domains.
val unapprovedDomains = userState?.hostToStateMap
    ?.filterValues { it == DomainVerificationUserState.DOMAIN_STATE_NONE }
```

### Java

```java
Context context = TODO("Your activity or fragment's Context");
DomainVerificationManager manager =
        context.getSystemService(DomainVerificationManager.class);
DomainVerificationUserState userState =
        manager.getDomainVerificationUserState(context.getPackageName());

Map<String, Integer> hostToStateMap = userState.getHostToStateMap();
List<String> verifiedDomains = new ArrayList<>();
List<String> selectedDomains = new ArrayList<>();
List<String> unapprovedDomains = new ArrayList<>();
for (String key : hostToStateMap.keySet()) {
    Integer stateValue = hostToStateMap.get(key);
    if (stateValue == DomainVerificationUserState.DOMAIN_STATE_VERIFIED) {
        // Domain has passed Android App Links verification.
        verifiedDomains.add(key);
    } else if (stateValue == DomainVerificationUserState.DOMAIN_STATE_SELECTED) {
        // Domain hasn't passed Android App Links verification, but the user has
        // associated it with an app.
        selectedDomains.add(key);
    } else {
        // All other domains.
        unapprovedDomains.add(key);
    }
}
```

#### Command-line program

When testing your app during development, you can run the following command to
query the verification state of the domains that your organization owns:  

```
adb shell pm get-app-links --user cur PACKAGE_NAME
```

In the following example output, even though the app failed verification for the
"example.org" domain, user 0 has manually approved the app in system settings,
and no other package is verified for that domain.  

```
com.example.pkg:
ID: ***
Signatures: [***]
Domain verification state:
  example.com: verified
  example.net: verified
  example.org: 1026
User 0:
  Verification link handling allowed: true
  Selection state:
    Enabled:
      example.org
    Disabled:
      example.com
      example.net
```

You can also use shell commands to simulate the process where the user selects
which app is associated with a given domain. A full explanation of these
commands is available from the output of `adb shell pm`.
| **Note:** The system can only associate one app at a time with a domain, even when you use shell commands. Some special cases, such as [installing two app variants
| simultaneously](https://developer.android.com/training/app-links/verify-applinks#multi-app-same-domain), require special handling to open a given web link in the intended app.

### Provide context for the request

Before you make this request for domain approval, provide some context for the
user. For example, you might show them a splash screen, a dialog, or a similar
UI element that explains to the user why your app should be the default handler
for a particular domain.

### Make the request

After the user understands what your app is asking them to do, make the request.
To do so, invoke an intent that includes the
[`ACTION_APP_OPEN_BY_DEFAULT_SETTINGS`](https://developer.android.com/reference/android/provider/Settings#ACTION_APP_OPEN_BY_DEFAULT_SETTINGS)
intent action, and a data string matching
`package:`<var translate="no">com.example.pkg</var> for the target app, as shown in
the following code snippet:  

### Kotlin

```kotlin
val context: Context = TODO("Your activity or fragment's Context")
val intent = Intent(Settings.ACTION_APP_OPEN_BY_DEFAULT_SETTINGS,
    Uri.parse("package:${context.packageName}"))
context.startActivity(intent)
```

### Java

```java
Context context = TODO("Your activity or fragment's Context");
Intent intent = new Intent(Settings.ACTION_APP_OPEN_BY_DEFAULT_SETTINGS,
    Uri.parse("package:" + context.getPackageName()));
context.startActivity(intent);
```

When the intent is invoked, users see a settings screen called **Open by
default** . This screen contains a radio button called **Open supported links**,
as shown in figure 1.

When the user turns on **Open supported links** , a set of checkboxes appear
under a section called **Links to open in this app** . From here, users can
select the domains that they want to associate with your app. They can also
select **Add link** to add domains, as shown in figure 2. When users later
select any link within the domains that they add, the link opens in your app
automatically.  
![When the radio button is enabled, a section near the bottom
includes checkboxes as well as a button called 'Add link'](https://developer.android.com/static/images/training/app-links/choose-domains.svg) **Figure 1.** System settings screen where users can choose which links open in your app by default.  
![Each checkbox represents a domain that you can add. The
dialog's buttons are 'Cancel' and 'Add.'](https://developer.android.com/static/images/training/app-links/add-domains.svg) **Figure 2.** Dialog where users can choose additional domains to associate with your app.

<br />

## Open domains in your app that your app cannot verify

Your app's main function might be to open links as a third party, without the
ability to verify its handled domains. If this is the case, explain to users
that, at that time when they select a web link, they cannot choose between a
first-party app and your (third-party) app. Users need to manually associate the
domains with your third-party app.

In addition, consider introducing a dialog or trampoline activity that allows
the user to open the link in the first-party app if the user prefers to do so,
acting as a proxy. Before setting up such a dialog or trampoline activity, set
up your app so that it has [package visibility](https://developer.android.com/training/package-visibility)
into the first-party apps that match your app's web intent filter.