我有一个没有onCreate（）方法的动态创建的Activity。我在其中一个onTouch（）方法中使用SharedPreferences时遇到了麻烦，该方法在我的createView（）方法中。当我调用getSharedPreferences（）时，我得到一个空指针异常。我猜测上下文为null，因为getApplicationContext（）和getBaseContext（）都会导致空指针异常。在这种情况下如何使用共享首选项？
这是我的createView（）代码：
public void createView(){
params = new WindowManager.LayoutParams(
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.MATCH_PARENT,
WindowManager.LayoutParams.TYPE_SYSTEM_ALERT,
WindowManager.LayoutParams.FLAG_NOT_TOUCH_MODAL,
PixelFormat.TRANSLUCENT);
RelativeLayout mainView = new RelativeLayout(service);
LinearLayout l = new LinearLayout(service);
RelativeLayout.LayoutParams param_one = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
l.setTag(first_tag);
l.setOrientation(LinearLayout.VERTICAL);
EditText second_test = new EditText(service);
second_test.setTextColor(Color.LTGRAY);
second_test.setWidth(440);
second_test.setTag(second_tag);
second_test.setTextSize(20);
LinearLayout.LayoutParams llp = new LinearLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
second_test.setLayoutParams(llp);
l.addView(second_test);
mainView.addView(l, param_one);
LinearLayout bottomLayout = new LinearLayout(service);
bottomLayout.setBackgroundColor(0x00ff0000);
RelativeLayout.LayoutParams bottomparam = new RelativeLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);
bottomLayout.setOnTouchListener(new OnTouchListener(){
@Override
public boolean onTouch(View v, MotionEvent event) {
Log.d(TAG, "onTouch");
View k = (View)v.getParent();
LinearLayout l = (LinearLayout) k.findViewWithTag(first_tag);
EditText second_test = (EditText) l.findViewWithTag(second_tag);
if(!second_test.getText().toString().isEmpty()){
String result = second_test.getText().toString();
Log.d(TAG, "Result is " + result);
SharedPreferences prefs = getSharedPreferences(TAG, MODE_PRIVATE);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("result", result);
editor.commit();
finish();
}
return true;
}
});
mainView.addView(bottomLayout, bottomparam);
overlayView = mainView;
}
这是logcat输出：
07-04 09:52:47.295: D/OverlayActivity(6146): onTouch
07-04 09:52:47.295: D/OverlayActivity(6146): Result is u=qwe&p=asd
07-04 09:52:47.295: E/InputEventReceiver(6146): Exception dispatching input event.
07-04 09:52:47.295: E/MessageQueue-JNI(6146): Exception in MessageQueue callback: handleReceiveCallback
07-04 09:52:47.305: E/MessageQueue-JNI(6146): java.lang.NullPointerException
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:161)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at com.example.test.OverlayActivity$2.onTouch(OverlayActivity.java:186)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.View.dispatchTouchEvent(View.java:7293)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2179)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1914)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2185)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1886)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.View.dispatchPointerEvent(View.java:7514)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3679)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3623)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4798)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4777)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4873)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:208)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.os.MessageQueue.nativePollOnce(Native Method)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.os.MessageQueue.next(MessageQueue.java:125)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.os.Looper.loop(Looper.java:135)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at android.app.ActivityThread.main(ActivityThread.java:5751)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at java.lang.reflect.Method.invokeNative(Native Method)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at java.lang.reflect.Method.invoke(Method.java:511)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1083)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:850)
07-04 09:52:47.305: E/MessageQueue-JNI(6146): at dalvik.system.NativeStart.main(Native Method)
07-04 09:52:47.305: W/dalvikvm(6146): threadid=1: thread exiting with uncaught exception (group=0x40c34a08)
07-04 09:52:47.310: E/AndroidRuntime(6146): FATAL EXCEPTION: main
07-04 09:52:47.310: E/AndroidRuntime(6146): java.lang.NullPointerException
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.content.ContextWrapper.getSharedPreferences(ContextWrapper.java:161)
07-04 09:52:47.310: E/AndroidRuntime(6146): at com.example.test.OverlayActivity$2.onTouch(OverlayActivity.java:186)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.View.dispatchTouchEvent(View.java:7293)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2179)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1914)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2185)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1886)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.View.dispatchPointerEvent(View.java:7514)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewRootImpl.deliverPointerEvent(ViewRootImpl.java:3679)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:3623)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:4798)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:4777)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:4873)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:208)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.os.MessageQueue.nativePollOnce(Native Method)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.os.MessageQueue.next(MessageQueue.java:125)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.os.Looper.loop(Looper.java:135)
07-04 09:52:47.310: E/AndroidRuntime(6146): at android.app.ActivityThread.main(ActivityThread.java:5751)
07-04 09:52:47.310: E/AndroidRuntime(6146): at java.lang.reflect.Method.invokeNative(Native Method)
07-04 09:52:47.310: E/AndroidRuntime(6146): at java.lang.reflect.Method.invoke(Method.java:511)
07-04 09:52:47.310: E/AndroidRuntime(6146): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1083)
07-04 09:52:47.310: E/AndroidRuntime(6146): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:850)
07-04 09:52:47.310: E/AndroidRuntime(6146): at dalvik.system.NativeStart.main(Native Method)
我做错了什么？
答案 0 :(得分：0)
好的，事实证明我可以在构造函数中使用上下文。傻我。