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After scanning for Bluetooth devices using start discovery I get mac addresses back, but without device names. Permissions are granted.
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Taifun
This issue often occurs because the device's name isn't immediately available during the initial discovery process. Here's a breakdown of why this happens and what you can do about it.
Why It Happens
The Bluetooth scanning process, specifically startDiscovery(), is designed to find nearby devices and their basic information as quickly as possible. The initial scan primarily returns the Bluetooth MAC address, also known as the device's unique identifier. The device name is a separate piece of information that needs to be retrieved through a more detailed process.
In many cases, the device name is included in the advertising packet sent out by the remote device. However, some devices may not include their name in these packets, or the packets might be truncated. When this happens, your app receives the MAC address but a null or empty string for the name.
Solutions
To get the device names, you'll need to use a different approach. The most common solution is to create a Bluetooth connection to the device after discovering its MAC address. Once a connection is established, you can query the device for its detailed information, including its name.
Here's a general outline of the steps:
- Start Discovery: Use startDiscovery() to get a list of nearby devices and their MAC addresses.
- Get MAC Addresses: Store the MAC addresses you find in a list.
- Create a Connection: For each MAC address, use the BluetoothDevice object to create a BluetoothSocket.
- Connect and Query: Attempt to connect to the device using the socket. If the connection is successful, you can now retrieve the device's name. You can use methods like device.getName() after the connection is established or when you have a BluetoothDevice object.
A second, more modern solution for Android developers, is to use the BluetoothLeScanner API for Bluetooth Low Energy (BLE) devices. This API provides more control over the scan process and can often retrieve device names more reliably. You can use a ScanFilter to only look for devices with specific names, but you can also perform a general scan and parse the ScanResult object, which often contains the device's name in its getDevice() or getScanRecord() methods.
By connecting to the device or using a more advanced scanning method, you can consistently get the device names you're looking for.