Question

我正在编写一个显示加速度计读数的应用程序，我昨天能够在主要活动中编写所有加速度计代码，它在模拟器和我的设备上运行良好。

但是今天我试图制作一个包含所有加速度计代码的函数，并返回整数数组中的三个整数X，Y，Z，所以我创建了一个代码，我认为它是正确的，但每次运行时项目模拟器给出错误“遗憾的是app-name已停止”。

所以我希望得到任何帮助。

logcat的：

04-27 20:39:27.098: W/dalvikvm(812): threadid=1: thread exiting with uncaught exception (group=0x40a70930)
04-27 20:39:27.118: E/AndroidRuntime(812): FATAL EXCEPTION: main
04-27 20:39:27.118: E/AndroidRuntime(812): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.accelerometer_sensor/com.example.accelerometer_sensor.MainActivity}: java.lang.NullPointerException
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.os.Handler.dispatchMessage(Handler.java:99)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.os.Looper.loop(Looper.java:137)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread.main(ActivityThread.java:5039)
04-27 20:39:27.118: E/AndroidRuntime(812):  at java.lang.reflect.Method.invokeNative(Native Method)
04-27 20:39:27.118: E/AndroidRuntime(812):  at java.lang.reflect.Method.invoke(Method.java:511)
04-27 20:39:27.118: E/AndroidRuntime(812):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-27 20:39:27.118: E/AndroidRuntime(812):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-27 20:39:27.118: E/AndroidRuntime(812):  at dalvik.system.NativeStart.main(Native Method)
04-27 20:39:27.118: E/AndroidRuntime(812): Caused by: java.lang.NullPointerException
04-27 20:39:27.118: E/AndroidRuntime(812):  at com.example.accelerometer_sensor.AccelerometerClass.AccelerometerInit(AccelerometerClass.java:20)
04-27 20:39:27.118: E/AndroidRuntime(812):  at com.example.accelerometer_sensor.MainActivity.onCreate(MainActivity.java:19)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.Activity.performCreate(Activity.java:5104)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
04-27 20:39:27.118: E/AndroidRuntime(812):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
04-27 20:39:27.118: E/AndroidRuntime(812):  ... 11 more
04-27 20:39:30.119: I/Process(812): Sending signal. PID: 812 SIG: 9

这是我的主要活动代码：

 package com.example.accelerometer_sensor;
    import android.os.Bundle;
    import android.app.Activity;
    import android.view.Menu;
    import android.widget.TextView;

    public class MainActivity extends Activity {

        int [] AccVal = new int[3];
        AccelerometerClass acc = new AccelerometerClass();
        TextView acceleration;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
             acc = new AccelerometerClass();

              AccVal = acc.AccelerometerInit();

                acceleration = (TextView)findViewById(R.id.acceleration);

                acceleration.setText("X: "+AccVal[0]+
                        "Y: "+AccVal[1]+
                        "Z: "+AccVal[2]);
        }

        @Override
        public boolean onCreateOptionsMenu(Menu menu) {
            // Inflate the menu; this adds items to the action bar if it is present.
            getMenuInflater().inflate(R.menu.activity_main, menu);
            return true;
        }


    }

这是我的AccelerometerClass Code ::

package com.example.accelerometer_sensor;

import android.content.Context;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorEventListener;
import android.hardware.SensorManager;

public class AccelerometerClass implements SensorEventListener 
{
    private static Context context;

    int [] Vals = new int[3];

    public int [] AccelerometerInit()
    {
        Sensor accelerometer;
        SensorManager sm;

        sm = (SensorManager)context.getSystemService(Context.SENSOR_SERVICE);       
        accelerometer=sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        sm.registerListener(this, accelerometer,SensorManager.SENSOR_DELAY_NORMAL); 

        return Vals;
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onSensorChanged(SensorEvent event) {
        // TODO Auto-generated method stub
        Vals[0]=(int)event.values[0];
        Vals[1]=(int)event.values[1];
        Vals[2]=(int)event.values[2];

    }

}

谢谢。

Answer 1

border-radius:1px中的上下文永远不会设置！

可能的解决方案：

AccelerometerClass

在您的活动中使用

public class AccelerometerClass implements SensorEventListener {

    int[] Vals = new int[3];

    public int[] AccelerometerInit(Context context) {
        SensorManager sm = (SensorManager) context.getSystemService(Context.SENSOR_SERVICE);
        Sensor accelerometer = sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);
        sm.registerListener(this, accelerometer, SensorManager.SENSOR_DELAY_NORMAL);

        return Vals;
    }

    @Override
    public void onAccuracyChanged(Sensor sensor, int accuracy) {

    }

     @Override
     public void onSensorChanged(SensorEvent event) {
         Vals[0] = (int) event.values[0];
         Vals[1] = (int) event.values[1];
         Vals[2] = (int) event.values[2];
    }
}

在课堂上编写android Accelerometer

1 个答案: