How to get an Android device's serial number, visible to the user in "Settings > About phone/tablet/device > Status > Serial number".

README.md

Devices tested

This code snippet has been successfully tested on the following devices and Android versions :

• Archos 133 Oxygen : 6.0.1
• Google Nexus 5 : 6.0.1
• Hannspree HANNSPAD 13.3" TITAN 2 (HSG1351) : 5.1.1
• Honor 5C (NEM-L51) : 7.0
• Honor 5X (KIW-L21) : 6.0.1
• Honor 9 Lite (LLD-L31) : 8.0
• Huawei M2 (M2-801w) : 5.1.1
• Samsung Galaxy S5 (SM-G900F) : 6.0.1
• Samsung Galaxy S6 (SM-G920F) : 7.0
• Samsung Galaxy Tab 4 (SM-T530) : 5.0.2
• Xiaomi Mi 8 (M1803E1A) : 8.1.0

Device.java

import android.os.Build;

import java.lang.reflect.Method;

public class Device {
    /**
     * @return The device's serial number, visible to the user in {@code Settings > About phone/tablet/device > Status
     * > Serial number}, or {@code null} if the serial number couldn't be found
     */
    public static String getSerialNumber() {
        String serialNumber;

        try {
            Class<?> c = Class.forName("android.os.SystemProperties");
            Method get = c.getMethod("get", String.class);

            // (?) Lenovo Tab (https://stackoverflow.com/a/34819027/1276306)
            serialNumber = (String) get.invoke(c, "gsm.sn1");

            if (serialNumber.equals(""))
                // Samsung Galaxy S5 (SM-G900F) : 6.0.1
                // Samsung Galaxy S6 (SM-G920F) : 7.0
                // Samsung Galaxy Tab 4 (SM-T530) : 5.0.2
                // (?) Samsung Galaxy Tab 2 (https://gist.github.com/jgold6/f46b1c049a1ee94fdb52)
                serialNumber = (String) get.invoke(c, "ril.serialnumber");

            if (serialNumber.equals(""))
                // Archos 133 Oxygen : 6.0.1
                // Google Nexus 5 : 6.0.1
                // Hannspree HANNSPAD 13.3" TITAN 2 (HSG1351) : 5.1.1
                // Honor 5C (NEM-L51) : 7.0
                // Honor 5X (KIW-L21) : 6.0.1
                // Huawei M2 (M2-801w) : 5.1.1
                // (?) HTC Nexus One : 2.3.4 (https://gist.github.com/tetsu-koba/992373)
                serialNumber = (String) get.invoke(c, "ro.serialno");

            if (serialNumber.equals(""))
                // (?) Samsung Galaxy Tab 3 (https://stackoverflow.com/a/27274950/1276306)
                serialNumber = (String) get.invoke(c, "sys.serialnumber");

            if (serialNumber.equals(""))
                // Archos 133 Oxygen : 6.0.1
                // Hannspree HANNSPAD 13.3" TITAN 2 (HSG1351) : 5.1.1
                // Honor 9 Lite (LLD-L31) : 8.0
                // Xiaomi Mi 8 (M1803E1A) : 8.1.0
                //serialNumber = Build.SERIAL;
                
                //To target Android O or newer
                //do add '<uses-permission android:name="android.permission.READ_PRIVILEGED_PHONE_STATE" />' in manifest
                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
					serialNumber = Build.getSerial();
				}else{
					serialNumber = Build.SERIAL;
				}

            // If none of the methods above worked
            if (serialNumber.equals(Build.UNKNOWN))
                serialNumber = null;
        } catch (Exception e) {
            e.printStackTrace();
            serialNumber = null;
        }

        return serialNumber;
    }
}

Did changes for Android O or never version