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[英]Application is crashing due to ClassCastException in Android studio
[英]ClassCastException in android application
我有一點問題。 我想創建帶有標題的導航抽屜,但是日食引發了類強制轉換異常。 問題出在適配器,但我找不到它。 你能幫我么。 這是我的適配器的代碼
public class NavDrawerAdapter extends ArrayAdapter<NavDrawerItem>{
private LayoutInflater inflater;
public NavDrawerAdapter(Context context, int textViewResourceId, NavDrawerItem[] objects ) {
super(context, textViewResourceId, objects);
this.inflater = LayoutInflater.from(context);
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View view = null ;
NavDrawerItem menuItem = this.getItem(position);
if ( menuItem.getType() == NavMenuItem.ITEM_TYPE ) {
view = getItemView(convertView, parent, menuItem );
}
else {
view = getSectionView(convertView, parent, menuItem);
}
return view ;
}
public View getItemView( View convertView, ViewGroup parentView, NavDrawerItem navDrawerItem ) {
NavMenuItem menuItem = (NavMenuItem) navDrawerItem ;
NavMenuItemHolder navMenuItemHolder = null;
if (convertView == null) {
convertView = inflater.inflate( R.layout.navdrawer_item, parentView, false);
TextView labelView = (TextView) convertView
.findViewById( R.id.navmenuitem_label );
ImageView i = (ImageView) convertView.findViewById(R.id.navmenuitem_icon);
navMenuItemHolder = new NavMenuItemHolder();
navMenuItemHolder.labelView = labelView ;
navMenuItemHolder.image = i;
convertView.setTag(navMenuItemHolder);
}
if ( navMenuItemHolder == null ) {
navMenuItemHolder = (NavMenuItemHolder) convertView.getTag();
}
navMenuItemHolder.labelView.setText(menuItem.getLabel().toString());
return convertView ;
}
public View getSectionView(View convertView, ViewGroup parentView,
NavDrawerItem navDrawerItem) {
NavMenuSection menuSection = (NavMenuSection) navDrawerItem ;
NavMenuSectionHolder navMenuItemHolder = null;
if (convertView == null) {
convertView = inflater.inflate( R.layout.navdrawer_section, parentView, false);
TextView labelView = (TextView) convertView
.findViewById( R.id.navmenusection_label );
navMenuItemHolder = new NavMenuSectionHolder();
navMenuItemHolder.labelView = labelView ;
convertView.setTag(navMenuItemHolder);
}
if ( navMenuItemHolder == null ) {
navMenuItemHolder = (NavMenuSectionHolder) convertView.getTag();
}
navMenuItemHolder.labelView.setText(menuSection.getLabel().toString());
return convertView ;
}
private static class NavMenuItemHolder {
private TextView labelView;
private ImageView image;
}
private static class NavMenuSectionHolder {
private TextView labelView;
}
}
這是我主要活動的代碼
public class MainActivity extends Activity{
private DrawerLayout drawerLayout;
private NavDrawerAdapter adapter;
private ListView mDrawerList;
private ImageView menu;
private RelativeLayout rightRL;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
drawerLayout = (DrawerLayout) findViewById(R.id.drawer_layout);
mDrawerList = (ListView) findViewById(R.id.left_drawer);
menu = (ImageView) findViewById(R.id.imageView1);
rightRL = (RelativeLayout) findViewById(R.id.whatYouWantInRightDrawerProfil);
NavDrawerItem[] m = new NavDrawerItem[]{
NavMenuSection.create(100, "Demos"),
NavMenuItem.create(101, "kako si", false, this),
NavMenuSection.create(200, "General"),
NavMenuItem.create(202, "Rate this app", false, this)
};
adapter = new NavDrawerAdapter(this, R.layout.navdrawer_item, m);
mDrawerList.setAdapter(adapter);
}
public void onRight(View view) {
drawerLayout.openDrawer(rightRL);
}
}
這是我的日食日志
致命例外:main java.lang.ClassCastException:com.markoKurt.zeljko.NavDrawerAdapter $ NavMenuSectionHolder無法轉換為com.markoKurt.zeljko.NavDrawerAdapter $ NavMenuItemHolder,位於com.markoKurt.zeljko.NavDrawerAdapter.getItemView(NavDrawerAdapter.52 com.markoKurt.zeljko.NavDrawerAdapter.getView(NavDrawerAdapter.java:25)在android.widget.AbsListView.obtainView(AbsListView.java:2449)在android.widget.ListView.measureHeightOfChildren(ListView.java:1250)在android.widget .ListView.onMeasure(ListView.java:1162)在android.view.View.measure(View.java:15504)在android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:617)在android.widget.RelativeLayout.onMeasure( RelativeLayout.java:399),位於android.view.View.measure(View.java:15504),位於android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:866),位於android.view.View.measure(View .java:15504)(位於android.widget.FrameLayout.onMeas上的android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059)) ure(FrameLayout.java:310)位於android.view.View.measure(View.java:15504)位於android.widget.LinearLayout.measureVertical(LinearLayout.java:833)位於android.widget.LinearLayout.onMeasure(LinearLayout.java :574)at android.view.View.measure(View.java:15504)com。android.widget.FrameLayout.onMeasure(FrameGroup.java:310)android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5059) .android.internal.policy.impl.PhoneWindow $ DecorView.onMeasure(PhoneWindow.java:2385)在android.view.View.measure(View.java:15504)在android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1979 )於android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1222)於android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1395)於android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1115)於android.view android.view.Choreographer $ CallbackRecord.run(Choreographer.java:725)上的.ViewRootImpl $ TraversalRunnable.run(ViewRootImpl.java:4526)在android.view.Choreographer.doCallbacks(Choreographer。 java:555)處android.view.Choreographer.doFrame(Choreographer.java:525)處android.view.Choreographer $ FrameDisplayEventReceiver.run(Choreographer.java:711)android.os.Handler.handleCallback(Handler.java:615) )在android.os.Handler.dispatchMessage(Handler.java:92)在android.os.Looper.loop(Looper.java:137)在android.app.ActivityThread.main(ActivityThread.java:4921)在java.lang com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:1027)上java.lang.reflect.Method.invoke(Method.java:511)上的.reflect.Method.invokeNative(本機方法) dalvik.system.NativeStart.main上的.android.internal.os.ZygoteInit.main(ZygoteInit.java:794)(本機方法)
請幫助我,並在此先感謝
您的問題與以下事實有關:您僅獲得一個null convertView
,因此NavMenuSectionHolder
或NavMenuItemHolder
設置了一次標記內容。 通常,當您必須處理多個convertView時,可以重寫getViewTypeCount
和getItemViewType
。 在您的情況下,兩個Holder類僅在ImageView
有所不同。 因此,我建議您只使用一個holder類(擴大一種布局),並在不需要時隱藏ImageView
我解決了問題。 我只需要添加
@Override
public int getViewTypeCount() {
return 2;
}
@Override
public int getItemViewType(int position) {
return this.getItem(position).getType();
}
@Override
public boolean isEnabled(int position) {
return getItem(position).isEnabled();
}
您試圖將navDrawerItem轉換為navMenuItem
NavMenuItem menuItem = (NavMenuItem) navDrawerItem;
用它改變
NavDrawerItem drawerItem = (NavDrawerItem ) navDrawerItem;
然后做相應的..
在getItemView和getSectionView中,您可以獲得不同的視圖,因此您需要檢查類實例。
public View getSectionView(View convertView, ViewGroup parentView,
NavDrawerItem navDrawerItem) {
NavMenuSection menuSection;
if (navDrawerItem !=null)
if (navDrawerItem instanceof NavMenuSection){
menuSection = navDrawerItem}
else {
menuSection = new NavMenuSection()
}else {
menuSection = new NavMenuSection()
}
public View getItemView( View convertView, ViewGroup parentView, NavDrawerItem navDrawerItem ) {
NavMenuItem menuItem = (NavMenuItem) navDrawerItem ;
NavMenuItemHolder navMenuItemHolder = null;
NavMenuSection menuSection;
if (menuItem!=null)
if (menuItem instanceof NavMenuItem){
menuItem = NavMenuItem
else {
menuItem = new NavMenuItem()
}else {
menuItem= new NavMenuItem()
}
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