# MultiThread 多線程 (Java)
###### tags: `java` `MultiThread`
## Intro
>使用於較花時間的演算，而且可以在背景執行(例如: 不用即時顯示再螢幕) EX: **Decode**
> **∈ 並發 OR multiTasking**
> 
**(Inside a core)**

## Example Code
### Decode QR code

class multiDecode implements Runnable {
        private Bitmap bm;
        private int no;
        public multiDecode(Bitmap temp,int idx) {
            bm = temp;
            no = idx;
        }
        private String _value = null;
        public void run() {
            String TAG = "getQR";
            while(_value == null){
                _value = QRcodeScanner.decodeQRImage(bm);

                if (_value != null && _value.length() > 1) {
                    try{
                        Thread.sleep(1000); //modified sleeping time
                    } catch (Exception e){
                        Log.d(TAG, e.getMessage());
                    }
                    api.judgeSendDiscoveredQR(no, _value);
                    try{
                        Thread.sleep(1000); // modified sleeping time
                    } catch (Exception e){
                        Log.d(TAG, e.getMessage());
                    }
                    String str;
                    str = _value.replaceAll("[^-0-9.]", "");
                    double val = Double.parseDouble(str);
                    Log.d(TAG, "\n\nQRno="+no+"string="+_value+"val= "+val+"iterate times="+"\n\n");
                    p3[no] = val;
                    break;
                }
            }
        }
    }

### Decode Input Data from Port

class LidarListener implements Runnable {
        private SerialPort _port;
        private LidarProxy _proxy;

        public LidarListener(LidarProxy proxy, SerialPort.Port port) {
            _proxy = proxy;
            _port = new SerialPort(115200, port);
        }
        public void run() {
            while (true) {
                try {
                    byte[] read = _port.read(9);
                    _proxy.lastReadDistance = read[2] & 0xFF;
                } catch (Exception e) {
                    DriverStation.reportError("LidarListener exception: " + e.toString(), false);
                }
            }
        }
    }