Question

 package com.example.ben.droidmice2;

 import android.hardware.Sensor;
 import android.hardware.SensorEvent;
 import android.hardware.SensorEventListener;
 import android.hardware.SensorManager;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle; 

 import com.example.ben.droidmice2.net.NetworkTask;

 public class MainActivity extends AppCompatActivity implements   SensorEventListener{

    private long lastUpdate = 0;
    private static final float TILT_THRESHOLD = 1.1f;

    private SensorManager sensorManager;

    //sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    private void getAccelerometer(SensorEvent event) {
        Sensor mySensor = event.sensor;

        if (mySensor.getType() == Sensor.TYPE_ACCELEROMETER) {
            float x = event.values[0];
            float y = event.values[1];
            //float z = event.values[2];
            long curTime = System.currentTimeMillis();

            if ((curTime - lastUpdate) > (1000/60)) {
                long diffTime = (curTime - lastUpdate);
                lastUpdate = curTime;

                if(Math.abs(x) > TILT_THRESHOLD || Math.abs(y) > TILT_THRESHOLD) {
                    int dx = (int)(x  * diffTime);
                    int dy = (int)(y  * diffTime);

                    new NetworkTask().execute("MOVE " + dx + "," + dy);
                }
            }
        }
    }


    @Override
    public void onSensorChanged(SensorEvent sensorEvent) {
        if (sensorEvent.sensor.getType() == Sensor.TYPE_ACCELEROMETER) {
            getAccelerometer(sensorEvent);
        }
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int i) {
        // Ignorable
    }


    protected void onPause() {
        super.onPause();
        sensorManager.unregisterListener(this);
    }


    @Override
    public void onResume(){
        super.onResume();
        // register this class as a listener for the orientation and
        // accelerometer sensors
        sensorManager.registerListener(this,
                sensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER),
                SensorManager.SENSOR_DELAY_FASTEST);
    }

 }

我正在尝试制作一个可以移动手机并使手机像鼠标一样的应用程序这是我的代码，告诉我我有一些问题尝试在空对象引用上调用虚拟方法'android.hardware.Sensor android.hardware.SensorManager.getDefaultSensor（int）' 对我来说，这里的OnResume（）里面没有问题有人帮忙吗？

尝试在空对象引用上调用虚拟方法

0 个答案: