问 SharedPreferences空指针异常

EN

我正在尝试保存一个整数，该整数将存储用户使用ImageView接口点击一个SharedPreferences的次数。但是，当我运行该应用程序时，它在声明sharedPreferences的行上给出了空指针异常：

SharedPreferences mSharedPreferences = this.getPreferences(Context.MODE_PRIVATE);

这是我第一次使用这个界面，这让我有点困惑。我不知道为什么会这样。这是日志：

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{koemdzhiev.com.eggyegg/koemdzhiev.com.eggyegg.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
        at android.app.ActivityThread.access$800(ActivityThread.java:151)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5254)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String android.content.Context.getPackageName()' on a null object reference
        at android.content.ContextWrapper.getPackageName(ContextWrapper.java:132)
        at android.app.Activity.getLocalClassName(Activity.java:4987)
        at android.app.Activity.getPreferences(Activity.java:5021)
        at koemdzhiev.com.eggyegg.MainActivity.<init>(MainActivity.java:20)
        at java.lang.reflect.Constructor.newInstance(Native Method)
        at java.lang.Class.newInstance(Class.java:1606)
        at android.app.Instrumentation.newActivity(Instrumentation.java:1066)
        at   

这是从Application类扩展的类中的代码：

public class EggyEggApplication extends Application {
@Override
public void onCreate() {
    SharedPreferences mSharedPreferences = this.getSharedPreferences(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY), Context.MODE_PRIVATE);
    SharedPreferences.Editor mEditor = mSharedPreferences.edit();
    if(mSharedPreferences.contains(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY))== false) {
        mEditor.putInt(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY), 0).apply();
}

这是我在主要活动中的代码：

public class MainActivity extends AppCompatActivity {
private static final String TAG = MainActivity.class.getSimpleName();
private int defaultValue;
private int i;
ImageView tapImage;
SharedPreferences mSharedPreferences = this.getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor mEditor = mSharedPreferences.edit();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    tapImage = (ImageView)findViewById(R.id.tapImage);
    tapImage.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            mEditor.putInt(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY),i);
            mEditor.commit();
    defaultValue = getResources().getInteger(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY);
    i = mSharedPreferences.getInt(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY),defaultValue);
    int defaultValue = getResources().getInteger(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY);
    long lastTapNumber = mSharedPreferences.getInt(getString(R.string.koemdzhiev_eggyegg_PREFERENCE_FILE_KEY),defaultValue);
    i = (int) lastTapNumber;
private boolean isNetworkAvailable() {
    ConnectivityManager connectivityManager
            = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
    NetworkInfo activeNetworkInfo = connectivityManager.getActiveNetworkInfo();
    return activeNetworkInfo != null && activeNetworkInfo.isConnected();
@Override