Question

For my device I want disable wifi when battery voltage level comes down to 3.4.

How to know the battery voltage is 3.4 programmatically?

Answer 1

You have to get the ACTION_BATTERY_CHANGED sticky intent and read the voltage from there:

IntentFilter ifilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
Intent batteryStatus = getContext().registerReceiver(null, ifilter);

int voltage = batteryStatus.getIntExtra(BatteryManager.EXTRA_VOLTAGE, -1);
if(voltage>0 && voltage<3400){
    //disable wifi
}