question: public void tryConnect ( ) { try { if ( TextUtils . isEmpty ( AppInfo . btAddress ) ) { return ; } if ( null == mAdapter ) { mAdapter = BluetoothAdapter . getDefaultAdapter ( ) ; } if ( null == mAdapter ) { return ; } if ( null == mBtService ) { mBtService = new BtService ( mContext ) ; } if ( mBtService . getState ( ) != BtService . STATE_CONNECTED ) { if ( ! TextUtils . isEmpty ( AppInfo . btAddress ) ) { BluetoothDevice device = mAdapter . getRemoteDevice ( AppInfo . btAddress ) ; mBtService . connect ( device ) ; return ; } } else { } } catch ( Exception e ) { e . printStackTrace ( ) ; } catch ( Error e ) { e . printStackTrace ( ) ; } }
target:  when bluetooth status is changed, if the printer is in use, connect it,else do nothing