Question

我是Android Studio和Java的新手，我尝试使用CO = new Double(sensor0).doubleValue();将变量sensor0转换为double，并且我想将变量传递给另一个类以使用它。但是我不能在另一个类中使用sensor0的变量。变量的值始终为0。

public class bt extends Activity {
public String sensor0, sensor1;
public double CO;

Button btnOn, btnOff, btnNext;
TextView txtArduino, txtString, txtStringLength, sensorView0, sensorView1, sensorView2, sensorView3;
Handler bluetoothIn;

final int handlerState = 0;                      //used to identify handler message
private BluetoothAdapter btAdapter = null;
private BluetoothSocket btSocket = null;
private StringBuilder recDataString = new StringBuilder();

private ConnectedThread mConnectedThread;


// SPP UUID service - this should work for most devices
private static final UUID ID = UUID.fromString("00001101-0000-1000-8000-00805F9B34FB");

// String for MAC address
private static String address;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_bt);

    //Link the buttons and textViews to respective views
    btnOn = (Button) findViewById(R.id.buttonOn);
    btnOff = (Button) findViewById(R.id.buttonOff);
    btnNext = (Button) findViewById(R.id.buttonNext);
    txtString = (TextView) findViewById(R.id.txtString);
    txtStringLength = (TextView) findViewById(R.id.testView1);
    sensorView0 = (TextView) findViewById(R.id.sensorView0);
    sensorView1 = (TextView) findViewById(R.id.sensorView1);
    sensorView2 = (TextView) findViewById(R.id.sensorView2);
    sensorView3 = (TextView) findViewById(R.id.sensorView3);


    bluetoothIn = new Handler() {
        public void handleMessage(android.os.Message msg) {
            if (msg.what == handlerState) {                                     //if message is what we want
                String readMessage = (String) msg.obj;                                                                // msg.arg1 = bytes from connect thread
                recDataString.append(readMessage);                                      //keep appending to string until ~
                int endOfLineIndex = recDataString.indexOf("~");                    // determine the end-of-line
                if (endOfLineIndex > 0) {                                           // make sure there data before ~
                    String dataInPrint = recDataString.substring(0, endOfLineIndex);    // extract string
                    txtString.setText("Data Received = " + dataInPrint);
                    int dataLength = dataInPrint.length();                          //get length of data received
                    txtStringLength.setText("String Length = " + String.valueOf(dataLength));

                    if (recDataString.charAt(0) == '#')                             //if it starts with # we know it is what we are looking for
                    {
                        sensor0 = recDataString.substring(1, 4);             //get sensor value from string between indices 1-5
                        sensor1 = recDataString.substring(5, 8);            //same again...
                        //String sensor2 = recDataString.substring(11, 15);
                        //String sensor3 = recDataString.substring(16, 20);

                        sensorView0.setText(" CO2 Value = " + sensor0 + "");    //update the textviews with sensor values
                        sensorView1.setText(" CO Value = " + sensor1 + "");
                       // sensorView2.setText(" Sensor 2 Voltage = " + sensor2 + "V");
                       // sensorView3.setText(" Sensor 3 Voltage = " + sensor3 + "V");
                    }
                    recDataString.delete(0, recDataString.length());                    //clear all string data
                    // strIncom =" ";
                    dataInPrint = " ";
                    CO = new Double(sensor0).doubleValue();

                }
            }
        }
    };

Answer 1

您需要允许访问此变量。最有效的方法是为此变量定义一个吸气剂。

在类中创建一个变量，然后在您的方法运行后填充字段
创建一个名为getC0（）的“公共”方法，该方法将返回您的值。
在类中，创建类的实例并且填充变量的逻辑运行后，您将需要此方法，您可以调用方法来获取值。

Answer 2

我将CO = new Double(sensor0).doubleValue();更改为double CO = Double.parseDouble(sensor0);。然后我通过使用代码从另一个类中获得0 bt SensorCO = new bt(); double COValue = SensorCO.CO;，下面是另一个类的代码

public void setBitmap( Bitmap bitmap ) {
    oldTime = (System.currentTimeMillis()+500)/1000;
    mBitmap = bitmap;

    if (!detector.isOperational()) {
        //Handle contingency
    } else {
        //Log.d("time1", SystemClock.currentThreadTimeMillis()+"");
        Frame frame = new Frame.Builder().setBitmap(bitmap).build();
        mFaces = detector.detect(frame);
    }

    bt SensorCO = new bt();
    double COValue = SensorCO.CO;

    newTime = (System.currentTimeMillis()+500)/1000;
    timeDifference = (newTime - oldTime);
    accumulate = (accumulate + timeDifference);
    CameraActivity.showScore(blinkCount, accumulate, COValue);


    if(isEyeBlinked()){
        accumulate = 0;
        Log.d("isEyeBlinked","eye blink is observed");
        blinkCount++;

    }
    if(accumulate > 6){
        playSound playSound1 = new playSound();
        playSound1.play(accumulate);

        }


    invalidate();
}

Answer 3

确保sensor0具有正确的值，然后替换

CO = new Double(sensor0).doubleValue();

使用

double CO = Double.parseDouble(sensor0);

如何将变量从内部类传递到另一个类

3 个答案: