無法實例活動羅盤活動

Question

我工作的羅盤應用程序， 的SensorManager是在onCreate()方法初始化，它被移動或使用onSensorChanged()方法動畫。

該應用運行和崩潰沒有給出任何輸出，我也檢查了LogCat也無法解決的主要問題，需要指導。

MainActivity.JAVA

package com.jdev.truenorthcompass; 

import android.hardware.Sensor; 
import android.hardware.SensorEvent; 
import android.hardware.SensorEventListener; 
import android.hardware.SensorManager; 
import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
import android.view.animation.Animation; 
import android.view.animation.RotateAnimation; 
import android.widget.ImageView; 
import android.widget.TextView; 

public abstract class MainActivity extends Activity implements SensorEventListener{ 

private ImageView image; 

private float currentDegree = 0f; 

private SensorManager mSensorManager; 

TextView tvHeading; 

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

    image = (ImageView)findViewById(R.id.imageViewCompass); 

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

    mSensorManager = (SensorManager) getSystemService(SENSOR_SERVICE); 
} 

@SuppressWarnings("deprecation") 
@Override 
protected void onResume(){ 
    super.onResume(); 

    mSensorManager.registerListener(this, mSensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION), SensorManager.SENSOR_DELAY_GAME); 
} 

@Override 
protected void onPause(){ 
    super.onPause(); 
    mSensorManager.unregisterListener(this); 
} 

public void OnSensorChanged(SensorEvent event){ 
    float degree = Math.round(event.values[0]); 

    tvHeading.setText("Heading:" + Float.toString(degree)+ "degrees"); 

    RotateAnimation ra = new RotateAnimation(
      currentDegree, 
      -degree, 
      Animation.RELATIVE_TO_SELF, 0.5f, 
      Animation.RELATIVE_TO_SELF, 0.5f); 

    ra.setDuration(210); 

    ra.setFillAfter(true); 

    image.startAnimation(ra); 
    currentDegree = -degree; 
} 

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

} 

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

} 

而對於TextView是用來顯示用戶的當前方位。 ImageView包含使用我們的MainActivity.java中的代碼正在像指南針一樣動畫的指南針圖像。 activity_main.xml中

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
xmlns:tools="http://schemas.android.com/tools" 
android:layout_width="match_parent" 
android:layout_height="match_parent" 
android:background="#fff" > 

<TextView 
    android:id="@+id/tvHeading" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_centerHorizontal="true" 
    android:layout_marginBottom="40dp" 
    android:layout_marginTop="20dp" 
    android:text="Heading: 0.0" /> 

<ImageView 
    android:id="@+id/imageViewCompass" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:layout_alignParentLeft="true" 
    android:layout_alignTop="@+id/tvHeading" 
    android:layout_marginTop="20dp" 
    android:src="@drawable/img_compass" /> 

這裏是錯誤報告LogCat：

07-11 05:27:26.203: D/dalvikvm(1195): newInstance failed: p0 i0 [0 a1 
07-11 05:27:26.203: D/AndroidRuntime(1195): Shutting down VM 
07-11 05:27:26.213: W/dalvikvm(1195): threadid=1: thread exiting with uncaught exception (group=0xb4abab90) 
07-11 05:27:26.243: E/AndroidRuntime(1195): FATAL EXCEPTION: main 
07-11 05:27:26.243: E/AndroidRuntime(1195): Process: com.jdev.truenorthcompass, PID: 1195 
07-11 05:27:26.243: E/AndroidRuntime(1195): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.jdev.truenorthcompass/com.jdev.truenorthcompass.MainActivity}: java.lang.InstantiationException: can't instantiate class com.jdev.truenorthcompass.MainActivity 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2102) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread.access$700(ActivityThread.java:135) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.os.Handler.dispatchMessage(Handler.java:102) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.os.Looper.loop(Looper.java:137) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread.main(ActivityThread.java:4998) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at java.lang.reflect.Method.invokeNative(Native Method) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at java.lang.reflect.Method.invoke(Method.java:515) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at dalvik.system.NativeStart.main(Native Method) 
07-11 05:27:26.243: E/AndroidRuntime(1195): Caused by: java.lang.InstantiationException: can't instantiate class com.jdev.truenorthcompass.MainActivity 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at java.lang.Class.newInstanceImpl(Native Method) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at java.lang.Class.newInstance(Class.java:1208) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.Instrumentation.newActivity(Instrumentation.java:1061) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2093) 
07-11 05:27:26.243: E/AndroidRuntime(1195):  ... 11 more 

任何幫助將不勝感激。謝謝！

另外，的Manifest.xml

<uses-sdk 
    android:minSdkVersion="14" 
    android:targetSdkVersion="19" /> 

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/> 
<uses-permission android:name="android.permission.ACCESS_MOCK_LOCATION"/> 
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/> 


<application 
    ... 
    <activity 
     android:name="com.jdev.truenorthcompass.MainActivity" 
     ... 
     <intent-filter> 
      <action android:name="android.intent.action.MAIN" /> 

      <category android:name="android.intent.category.LAUNCHER" /> 
     </intent-filter> 
    </activity> 
</application> 

Answer 1

類是abstract

public abstract class MainActivity 

抽象類不能直接實例化