我在创建listView时遇到错误
错误如下
FATAL EXCEPTION: main
java.lang.NullPointerException
at com.teamXDev.onlineordering.FinalOrderListAdapter.getView(FinalOrderListAdapter.java:131)
at android.widget.AbsListView.obtainView(AbsListView.java:2090)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1485)
at android.widget.ListView.onMeasure(ListView.java:1348)
at android.view.View.measure(View.java:12937)
at android.widget.RelativeLayout.measureChild(RelativeLayout.java:579)
at android.widget.RelativeLayout.onMeasure(RelativeLayout.java:392)
at android.view.View.measure(View.java:12937)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5045)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
at android.view.View.measure(View.java:12937)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:812)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:553)
at android.view.View.measure(View.java:12937)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5045)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:293)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2180)
at android.view.View.measure(View.java:12937)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1227)
at android.view.ViewRootImpl.handleMessage(ViewRootImpl.java:2700)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:156)
at android.app.ActivityThread.main(ActivityThread.java:5099)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:511)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
at dalvik.system.NativeStart.main(Native Method)
D/Process(31726): killProcess, pid=31726
我的布局：activity_final_order.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="@+id/lbl_FinalOrder"
android:layout_width="match_parent"
android:layout_height="45dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_margin="4dp"
android:background="#8d9190"
android:gravity="center"
android:text="YOUR ORDER"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textColor="#FFF" />
<ListView
android:id="@+id/lView_FinalOrder"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="@+id/lbl_FinalOrder"
>
</ListView>
</RelativeLayout>
我的列表视图子项：final_order_child_item.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#eeeeee"
android:orientation="vertical"
android:padding="5dp" >
<TextView
android:id="@+id/lbl_itemName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:paddingLeft="2dp"
android:text="Item 1"
android:textAppearance="?android:attr/textAppearanceMedium" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:background="#8d9190"
android:layout_below="@id/lbl_itemName"
android:orientation="horizontal" >
<TextView
android:id="@+id/lbl_itemQty"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_gravity="center_vertical"
android:layout_margin="2dp"
android:gravity="left"
android:padding="5dp"
android:text="Qty"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/lbl_itemServingSize"
android:layout_width="wrap_content"
android:layout_height="match_parent"
android:layout_margin="2dp"
android:layout_gravity="center_vertical"
android:padding="5dp"
android:text="Regular"
android:textAppearance="?android:attr/textAppearanceMedium" />
<TextView
android:id="@+id/lbl_itemTotalCost"
android:layout_width="0dp"
android:layout_height="match_parent"
android:layout_margin="2dp"
android:layout_gravity="center_vertical"
android:layout_weight="1"
android:gravity="right"
android:padding="5dp"
android:layout_marginRight="10dp"
android:text="120"
android:textAppearance="?android:attr/textAppearanceMedium" />
</LinearLayout>
</RelativeLayout>
我的listViewClass：FinalOrder
public class FinalOrder extends Activity {
private static final String TAG = "FinalOrder";
Button btn_CheckOut, btn_Apply;
TextView txt_coupneCode, txt_subTotal, txt_finalTotal, txt_taxesFees,
txt_couponOff;
ListView lView_finalOrder;
ArrayList<String> orderedItemName = new ArrayList<String>();
ArrayList<String> orderedItemQty = new ArrayList<String>();
ArrayList<String> orderedItemServingSize = new ArrayList<String>();
ArrayList<String> orderedItemTotalCost = new ArrayList<String>();
Boolean logedIn = false;
SessionManager session;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_final_order);
lView_finalOrder = (ListView) findViewById(R.id.lView_FinalOrder);
orderedItemName.add("SampleItem");
orderedItemQty.add("1");
orderedItemServingSize.add("Regular");
orderedItemTotalCost.add("0.0");
setView();
}
private void setView() {
FinalOrderListAdapter fItemAdapter = new FinalOrderListAdapter(
lView_finalOrder.getContext(), R.layout.final_order_child_item,
orderedItemName, orderedItemQty, orderedItemServingSize,
orderedItemTotalCost);
Log.e("setView","setting Adapter");
lView_finalOrder.setAdapter(fItemAdapter);
}
}
我的ListView适配器类：FinalOrderListAdapter
public class FinalOrderListAdapter extends BaseAdapter {
// local variables that will be assigned data from the activity
ArrayList<String> orderedItemName = new ArrayList<String>();
ArrayList<String> orderedItemQty = new ArrayList<String>();
ArrayList<String> orderedItemServingSize = new ArrayList<String>();
ArrayList<String> orderedItemTotalCost = new ArrayList<String>();
// Resource ID of the list
int resourceID;
// To inflate the list view
LayoutInflater inflater;
// the Context
Context context;
// Template Class of Graphic Elements which list Item will hold
private static class ListItemHolder {
TextView lbl_itemName, lbl_itemQty, lbl_itemServingSize,
lbl_itemTotalCost;
}
// constructor which receives the context, list Resource ID along with data
// to be displayed from the activity class
public FinalOrderListAdapter(Context _ctx, int _rID,
ArrayList<String> _orderedItemName,
ArrayList<String> _orderedItemQty,
ArrayList<String> _orderedItemServingSize,
ArrayList<String> _orderedItemTotalCost) {
super();
// receive the info from activity variables to local class variable
this.orderedItemName = _orderedItemName;
this.orderedItemQty = _orderedItemQty;
this.orderedItemServingSize = _orderedItemServingSize;
this.orderedItemTotalCost = _orderedItemTotalCost;
// receive the context from the activity
this.context = _ctx;
// receive the resource ID of the list
this.resourceID = _rID;
// initialize the inflater with the context received
this.inflater = LayoutInflater.from(_ctx);
}
@Override
public int getCount() {
return orderedItemName.size();
}
@Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return null;
}
@Override
public long getItemId(int arg0) {
// TODO Auto-generated method stub
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// This view will inflate UI and add the list Item to it
final ListItemHolder listItem;
/*
* covertView is layout of the Child Item of list parent is the parent
* of list view layout position of the list Item
*/
if (convertView == null) {
// if this view is null its first Item of list that needs to be
// created
// get layout inflater
LayoutInflater vInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
convertView = vInflater.inflate(resourceID, parent, false);
/*
* Initialize the Item holder class view variables with the view
* elements of convert view i.e. nothing but list child item layout
*/
listItem = new ListItemHolder();
listItem.lbl_itemName = (TextView) convertView
.findViewById(R.id.lbl_itemName);
listItem.lbl_itemQty = (TextView) convertView
.findViewById(R.id.lbl_itemQty);
listItem.lbl_itemServingSize = (TextView) convertView
.findViewById(R.id.lbl_itemServingSize);
listItem.lbl_itemTotalCost = (TextView) convertView
.findViewById(R.id.lbl_itemCost);
// assigns the tag listItem to the
convertView.setTag(listItem);
} else {
// reading list
listItem = (ListItemHolder) convertView.getTag();
}
// setting label values from the received data from the string arrays
/* line: 129 is below line */
listItem.lbl_itemName.setText(orderedItemName.get(position));
listItem.lbl_itemQty.setText(orderedItemQty.get(position));
listItem.lbl_itemServingSize.setText(orderedItemServingSize.get(position));
listItem.lbl_itemTotalCost.setText(orderedItemTotalCost.get(position));
return convertView;
}
}
知道这个错误的原因吗？
答案 0 :(得分：1)
正如tolgap和日志所述： 问题在131号线上。
我错误地将文字设置为
listItem.lbl_itemTotalCost.setText(orderedItemTotalCost.get(position));
但是使用
错误地初始化了lbl_itemTotalCostlistItem.lbl_itemTotalCost = (TextView) convertView
.findViewById(R.id.lbl_itemCost);
而不是
listItem.lbl_itemTotalCost = (TextView) convertView
.findViewById(R.id.lbl_itemTotalCost);
P.S。我错误地将资源分配给膨胀的UI，这在子项目布局中不存在。
白痴错误！ ：P
答案 1 :(得分：0)
修改你的获取视图就像这样。
@Override
public View getView(int position, View convertView, ViewGroup parent) {
// This view will inflate UI and add the list Item to it
View rowView = convertView;
/*
* rowView is layout of the Child Item of list parent is the parent
* of list view layout position of the list Item
*/
if (rowView== null) {
// if this view is null its first Item of list that needs to be
// created
// get layout inflater
LayoutInflater vInflater = (LayoutInflater) context
.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
rowView= vInflater.inflate(resourceID, parent, false);
/*
* Initialize the Item holder class view variables with the view
* elements of convert view i.e. nothing but list child item layout
*/
ListItemHolder listItem = new ListItemHolder();
listItem.lbl_itemName = (TextView) convertView
.findViewById(R.id.lbl_itemName);
listItem.lbl_itemQty = (TextView) convertView
.findViewById(R.id.lbl_itemQty);
listItem.lbl_itemServingSize = (TextView) convertView
.findViewById(R.id.lbl_itemServingSize);
listItem.lbl_itemTotalCost = (TextView) convertView
.findViewById(R.id.lbl_itemCost);
// assigns the tag listItem to the
rowView.setTag(listItem);
} else {
// reading list
ListItemHolder item = (ListItemHolder) rowView.getTag();
}
// setting label values from the received data from the string arrays
listItem.lbl_itemName.setText(orderedItemName.get(position));
listItem.lbl_itemQty.setText(orderedItemQty.get(position));
listItem.lbl_itemServingSize.setText(orderedItemServingSize.get(position));
listItem.lbl_itemTotalCost.setText(orderedItemTotalCost.get(position));
return rowView;
}
}