public SlidingMenu(Context context, AttributeSet attrs) {

super(context, attrs);

WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);

DisplayMetrics outMetrics = new DisplayMetrics();

wm.getDefaultDisplay().getMetrics(outMetrics);

mScreenWidth = outMetrics.widthPixels;

// 把dp或者sp转化为px

mMeunRightPadding = (int) TypedValue.applyDimension(

TypedValue.COMPLEX_UNIT_DIP, 50, context.getResources()

.getDisplayMetrics());

}

老师这行代码 wm.getDefaultDisplay().getMetrics(outMetrics);  一直报NullPointerException异常不知道是为什么

NOTE: This project contains Java compilation errors, which can cause rendering failures for custom views. Fix compilation problems first.

Exception raised during rendering: com.android.layoutlib.bridge.MockView cannot be cast to android.view.ViewGroup

Exception details are logged in Window > Show View > Error Log

The following classes could not be instantiated:

- com.example.stock.slidingmenu.view.SlidingMenu (Open Class, Show Error Log)

See the Error Log (Window > Show View) for more details.

Tip: Use View.isInEditMode() in your custom views to skip code when shown in Eclipse

java.lang.NullPointerException

    at com.example.stock.slidingmenu.view.SlidingMenu.<init>(SlidingMenu.java:41)

    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(    at sun.reflect.NativeConstructorAccessorImpl.newInstance(    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(    at java.lang.reflect.Constructor.newInstance(    at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.instantiateClass(ProjectCallback.java:422)

    at com.android.ide.eclipse.adt.internal.editors.layout.ProjectCallback.loadView(ProjectCallback.java:179)

    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:207)

    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:135)

    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:739)

    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:64)

    at android.view.LayoutInflater.rInflate(LayoutInflater.java:711)

    at android.view.LayoutInflater.inflate(LayoutInflater.java:489)

    at android.view.LayoutInflater.inflate(LayoutInflater.java:372)