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我對android studio的編程非常新穎，我一直在試圖弄清楚這一點，但我不確定是什麼問題是。我試圖同時使用加速度計和GPS的組合來獲得更準確的加速度和設備速度，但是當我嘗試啓動加速度計時，會引發此異常：在Android Studio中同時使用加速度計和GPS的問題
java.lang.RuntimeException: Unable to start activity ComponentInfo
java.lang.RuntimeException: Unable to start activity ComponentInfo
致：java.lang.IllegalStateException：的onCreate（）之前不爲活動提供系統的服務
這裏是在MainActivity：
package com.example.accelerometergps;
import android.content.Context;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity implements LocationListener {
private Accelerometer a;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
LocationManager l = (LocationManager) this.getSystemService(Context.LOCATION_SERVICE);
l.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
this.onLocationChanged(null);
a = new Accelerometer();
//It works fine if I remove the following line
a.registerListener();
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
@Override
public void onLocationChanged(Location location) {
TextView tv = (TextView) findViewById(R.id.textView);
if (location == null) {
tv.setText("no GPS");
} else {
double temp = location.getSpeed();
double speed = 2.23694 * temp;
// tv.setText(String.valueOf(speed));
}
}
@Override
public void onStatusChanged(String provider, int status, Bundle extras) {
}
@Override
public void onProviderEnabled(String provider) {
}
@Override
public void onProviderDisabled(String provider) {
}
}
這裏是Accelerometer類：
package com.example.accelerometergps;
import android.app.Activity;
import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;
import android.os.Bundle;
import android.widget.EditText;
import android.widget.TextView;
public class Accelerometer extends Activity implements SensorEventListener {
private SensorManager mSensorManager;
private Sensor mAccelerometer;
double[] accelerationList = new double[5];
double averageAcceleration;
protected void onResume() {
super.onResume();
mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
}
protected void onPause() {
super.onPause();
mSensorManager.unregisterListener(this);
}
@Override
public void onAccuracyChanged(Sensor sensor, int accuracy) {
}
public void registerListener() {
mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);
mAccelerometer = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
mSensorManager.registerListener(this, mAccelerometer, SensorManager.SENSOR_DELAY_NORMAL);
}
public void unregisterListener() {
mSensorManager.unregisterListener(this);
}
@Override
public void onSensorChanged(SensorEvent event) {
float x = event.values[0];
float y = event.values[1];
float z = event.values[2];
double temp = sumAcceleration(x, y, z);
addToList(temp);
averageAcceleration = accelerationListAverage();
}
public double sumAcceleration(float i, float j, float k) {
float temp = i * i + j * j + k * k;
double linearAcceleration = Math.sqrt(temp) - 9.8;
return linearAcceleration;
}
public double accelerationListAverage() {
double sum = 0;
for (int i = 0; i < 5; i++) {
sum += accelerationList[i];
}
return (sum/5);
}
public void addToList(double a) {
double b = accelerationList[0];
double c = accelerationList[1];
double d = accelerationList[2];
double e = accelerationList[3];
accelerationList[0] = a;
accelerationList[1] = b;
accelerationList[2] = c;
accelerationList[3] = d;
accelerationList[4] = e;
}
public double getAcceleration() {
return averageAcceleration;
}
}
任何幫助或建議將不勝感激，謝謝你提前。