我已经在我的应用程序中实现了一个自定义网格视图。我正在使用StaggeredGridView。我能够在我的代码中实现它但现在当我尝试滚动网格视图时，我的应用程序崩溃，因为它获得 mScrollListener null 我没有得到滚动侦听器如何获取空值。
这是我的代码：
public class CompareSelectorGridFragments extends Fragment {
private List<StaggeredGridViewItem> itemlist;
private List<catagoriesListModal> _categories;
private StaggeredGridView mStaggeredView;
private View mRootView;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Session.ChangeFragmentOnBackPressHandlerWithBack(null, null, "", 0);
Session.getmCountImage().setvisibilityOff();
itemlist = new ArrayList<StaggeredGridViewItem>();
mRootView = inflater.inflate(
R.layout.fragment_product_selector_for_compare, container,
false);
if (getResources().getBoolean(R.bool.landscape_only)) {
getActivity().setRequestedOrientation(
ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
} else {
getActivity().setRequestedOrientation(
ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}
initUI(mRootView);
return mRootView;
}
private void initUI(View rootView) {
mStaggeredView = new StaggeredGridView(getActivity());
mStaggeredView.initialize(3, StaggeredGridView.Mode.FIXED);
mStaggeredView.setOnScrollListener(scrollListener);
mStaggeredView = (StaggeredGridView) rootView
.findViewById(R.id.grid_product_selector);
StaggeredGridViewItem item = null;
for (int i = 0; i < DummyData.getSelectorList().size(); i++) {
_categories = DummyData.getSelectorList().get(i).getCategories();
item = new ProductSelectorCompareAdapter(getActivity(), DummyData
.getSelectorList().get(i).getName(), DummyData
.getSelectorList().get(i).getImage(), _categories);
itemlist.add(item);
}
mStaggeredView.addItemsList(itemlist);
}
private OnScrollListener scrollListener = new OnScrollListener() {
public void onTop() {
}
public void onScroll() {
}
public void onBottom() {
}
};
}
以下是适配器的代码：
public class SelectorCompareAdapter extends StaggeredGridViewItem {
Activity activity;
List<SelectorTest> listSelector;
private Button btn;
List<catagoriesListModal> mCategories;
private View mView;
private int mHeight;
private String Name;
private int Image;
public SelectorCompareAdapter(Activity activity, String name,
int image, List<catagoriesListModal> _categories) {
this.activity = activity;
this.Name = name;
this.Image = image;
this.mCategories = _categories;
}
static class ViewHolder {
TextView tvProductName;
ImageView imgView;
View viewRightLine;
ScrollView scrlLstItems;
LinearLayout lnrLayout;
}
@Override
public View getView(LayoutInflater inflater, ViewGroup parent) {
final ViewHolder viewHolder;
mView = inflater.inflate(R.layout.selector_item_compare, null);
if (mView != null) {
viewHolder = new ViewHolder();
viewHolder.tvProductName = (TextView) mView
.findViewById(R.id.tv_product);
viewHolder.imgView = (ImageView) mView
.findViewById(R.id.img_product);
viewHolder.viewRightLine = (View) mView
.findViewById(R.id.view_right_line);
viewHolder.lnrLayout = (LinearLayout) mView
.findViewById(R.id.lnr_test);
viewHolder.tvProductName.setText(Name);
viewHolder.imgView.setImageResource(Image);
viewHolder.imgView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
viewHolder.lnrLayout.setVisibility(View.VISIBLE);
viewHolder.imgView.setVisibility(View.GONE);
for (int i = 0; i < mCategories.size(); i++) {
btn = new Button(activity);
btn.setText(mCategories.get(i).getName());
viewHolder.lnrLayout.addView(btn);
int idx = viewHolder.lnrLayout.indexOfChild(btn);
btn.setTag(Integer.toString(idx));
btn.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
String idxStr = (String) v.getTag();
Toast.makeText(activity, idxStr,
Toast.LENGTH_SHORT).show();
}
});
}
}
});
viewHolder.tvProductName.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
if (activity.getResources().getBoolean(
R.bool.landscape_only)) {
viewHolder.lnrLayout.removeAllViews();
viewHolder.lnrLayout.setVisibility(View.GONE);
viewHolder.imgView.setVisibility(View.VISIBLE);
}
}
});
mView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) mView.getTag();
}
return mView;
}
@Override
public int getViewHeight(LayoutInflater inflater, ViewGroup parent) {
LinearLayout item_containerLinearLayout = (LinearLayout) mView
.findViewById(R.id.ll_container);
item_containerLinearLayout.measure(MeasureSpec.UNSPECIFIED,
MeasureSpec.UNSPECIFIED);
mHeight = item_containerLinearLayout.getMeasuredHeight();
return mHeight;
}
}
记录错误： -
08-31 08:37:28.946: E/AndroidRuntime(5076): java.lang.NullPointerException
08-31 08:37:28.946: E/AndroidRuntime(5076): at com.mss.skyjack.customgridview.StaggeredGridView.onScrollChanged(StaggeredGridView.java:243)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.View.scrollTo(View.java:10210)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.widget.ScrollView.onOverScrolled(ScrollView.java:763)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.View.overScrollBy(View.java:16879)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.widget.ScrollView.onTouchEvent(ScrollView.java:634)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.View.dispatchTouchEvent(View.java:7384)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2205)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1940)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:2211)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:1954)
08-31 08:37:28.946: E/AndroidRuntime(5076): at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1966)
08-31 08:37:28.946: E/AndroidRuntime(5076): at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1418)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.app.Activity.dispatchTouchEvent(Activity.java:2424)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.support.v7.internal.view.WindowCallbackWrapper.dispatchTouchEvent(WindowCallbackWrapper.java:59)
08-31 08:37:28.946: E/AndroidRuntime(5076): at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1914)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.View.dispatchPointerEvent(View.java:7564)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$ViewPostImeInputStage.processPointerEvent(ViewRootImpl.java:3883)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$ViewPostImeInputStage.onProcess(ViewRootImpl.java:3778)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$AsyncInputStage.forward(ViewRootImpl.java:3483)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$AsyncInputStage.apply(ViewRootImpl.java:3540)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.onDeliverToNext(ViewRootImpl.java:3429)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.forward(ViewRootImpl.java:3398)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.apply(ViewRootImpl.java:3406)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$InputStage.deliver(ViewRootImpl.java:3379)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl.deliverInputEvent(ViewRootImpl.java:5419)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl.doProcessInputEvents(ViewRootImpl.java:5399)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl.enqueueInputEvent(ViewRootImpl.java:5370)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl$WindowInputEventReceiver.onInputEvent(ViewRootImpl.java:5493)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.InputEventReceiver.dispatchInputEvent(InputEventReceiver.java:182)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.InputEventReceiver.nativeConsumeBatchedInputEvents(Native Method)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.InputEventReceiver.consumeBatchedInputEvents(InputEventReceiver.java:174)
08-31 08:37:28.946: E/AndroidRuntime(5076): at android.view.ViewRootImpl.doConsumeBatchedInput(ViewRootImp
答案 0 :(得分：1)
或者只是在findViewById调用之后尝试调用setScrollListener