这是一个更简单的答案:

public String getMyPhoneNumber()
{
    return ((TelephonyManager) getSystemService(TELEPHONY_SERVICE))
            .getLine1Number();
}

以下是我找到的解决方案的组合(这里是示例项目，如果你也想检查自动填充):

清单

    <uses-permission android:name="android.permission.READ_PHONE_STATE" />

build.gradle

    implementation "com.google.android.gms:play-services-auth:17.0.0"

MainActivity.kt

class MainActivity : AppCompatActivity() {
    private lateinit var googleApiClient: GoogleApiClient

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        tryGetCurrentUserPhoneNumber(this)
        googleApiClient = GoogleApiClient.Builder(this).addApi(Auth.CREDENTIALS_API).build()
        if (phoneNumber.isEmpty()) {
            val hintRequest = HintRequest.Builder().setPhoneNumberIdentifierSupported(true).build()
            val intent = Auth.CredentialsApi.getHintPickerIntent(googleApiClient, hintRequest)
            try {
                startIntentSenderForResult(intent.intentSender, REQUEST_PHONE_NUMBER, null, 0, 0, 0);
            } catch (e: IntentSender.SendIntentException) {
                Toast.makeText(this, "failed to show phone picker", Toast.LENGTH_SHORT).show()
            }
        } else
            onGotPhoneNumberToSendTo()

    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        if (requestCode == REQUEST_PHONE_NUMBER) {
            if (resultCode == Activity.RESULT_OK) {
                val cred: Credential? = data?.getParcelableExtra(Credential.EXTRA_KEY)
                phoneNumber = cred?.id ?: ""
                if (phoneNumber.isEmpty())
                    Toast.makeText(this, "failed to get phone number", Toast.LENGTH_SHORT).show()
                else
                    onGotPhoneNumberToSendTo()
            }
        }
    }

    private fun onGotPhoneNumberToSendTo() {
        Toast.makeText(this, "got number:$phoneNumber", Toast.LENGTH_SHORT).show()
    }


    companion object {
        private const val REQUEST_PHONE_NUMBER = 1
        private var phoneNumber = ""

        @SuppressLint("MissingPermission", "HardwareIds")
        private fun tryGetCurrentUserPhoneNumber(context: Context): String {
            if (phoneNumber.isNotEmpty())
                return phoneNumber
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
                val subscriptionManager = context.getSystemService(Context.TELEPHONY_SUBSCRIPTION_SERVICE) as SubscriptionManager
                try {
                    subscriptionManager.activeSubscriptionInfoList?.forEach {
                        val number: String? = it.number
                        if (!number.isNullOrBlank()) {
                            phoneNumber = number
                            return number
                        }
                    }
                } catch (ignored: Exception) {
                }
            }
            try {
                val telephonyManager = context.getSystemService(Context.TELEPHONY_SERVICE) as TelephonyManager
                val number = telephonyManager.line1Number ?: ""
                if (!number.isBlank()) {
                    phoneNumber = number
                    return number
                }
            } catch (e: Exception) {
            }
            return ""
        }
    }
}

这个问题没有保证的解决方案，因为电话号码不是物理地存储在所有sim卡上，也不是从网络广播到电话上。在一些需要物理地址验证的国家尤其如此，只有在验证之后才会分配号码。电话号码分配是在网络上进行的，并且可以在不改变SIM卡或设备的情况下进行更改(例如，这就是支持移植的方式)。

我知道这很痛苦，但最有可能的最好的解决方案是让用户输入一次他/她的电话号码并存储它。

while working on a security app which needed to get the phone number of who so ever my phone might get into their hands, I had to do this; 1. receive Boot completed and then try getting Line1_Number from telephonyManager which returns a string result. 2. compare the String result with my own phone number and if they don't match or string returns null then, 3. secretly send an SMS containing the string result plus a special sign to my office number. 4. if message sending fails, start a service and keep trying after each hour until sent SMS pending intent returns successful. With this steps I could get the number of the person using my lost phone. it doesn't matter if the person is charged.

添加这个依赖: 实现“com.google.android.gms: play-services-auth: 18.0.0”

获取电话号码列表使用这个:

val hintRequest = HintRequest.Builder()
    .setPhoneNumberIdentifierSupported(true)
    .build()

val intent = Credentials.getClient(context).getHintPickerIntent(hintRequest)

startIntentSenderForResult(
    intent.intentSender,
    PHONE_NUMBER_FETCH_REQUEST_CODE,
    null,
    0,
    0,
    0,
    null
)

点击播放服务对话框后:

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent? { 
    super.onActivityResult(requestCode, resultCode, data)

    if (requestCode == PHONE_NUMBER_FETCH_REQUEST_CODE) {
        data?.getParcelableExtra<Credential>(Credential.EXTRA_KEY)?.id?.let { 
            useFetchedPhoneNumber(it)
        }
    }
}

不建议使用TelephonyManager，因为它要求应用程序在运行时需要READ_PHONE_STATE权限。

<uses-permission android:name="android.permission.READ_PHONE_STATE"/> 

应该使用谷歌的播放服务进行身份验证，它将能够允许用户选择使用哪个phoneNumber，并处理多个SIM卡，而不是我们试图猜测哪一个是主SIM卡。

implementation "com.google.android.gms:play-services-auth:$play_service_auth_version"

fun main() {
    val googleApiClient = GoogleApiClient.Builder(context)
        .addApi(Auth.CREDENTIALS_API).build()

    val hintRequest = HintRequest.Builder()
        .setPhoneNumberIdentifierSupported(true)
        .build()

    val hintPickerIntent = Auth.CredentialsApi.getHintPickerIntent(
        googleApiClient, hintRequest
    )

    startIntentSenderForResult(
        hintPickerIntent.intentSender, REQUEST_PHONE_NUMBER, null, 0, 0, 0
    )
}

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    when (requestCode) {
        REQUEST_PHONE_NUMBER -> {
            if (requestCode == Activity.RESULT_OK) {
                val credential = data?.getParcelableExtra<Credential>(Credential.EXTRA_KEY)
                val selectedPhoneNumber = credential?.id
            }
        }
    }
}