我正在开发一个指南针应用程序，在该方法SensorManager中进行了初始化，onCreate()并使用该方法对其进行了移动或动画onSensorChanged()处理。
应用程序在没有给出任何输出的情况下运行和崩溃，我LogCat也检查了但无法解决主要问题，需要指导。
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 forTextView则用于显示用户当前的标题。ImageView包含指南针图像，该图像使用我们的MainActivity.java.
activity_main.xml
<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" />
这是错误报告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
任何帮助将不胜感激。谢谢你！
还有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>