我很难解决我的代码问题。
当按ListView项中的删除按钮时，理想情况下应该删除该项，并在调用notifyDataSetChanged（）时刷新列表视图;
然而，情况并非如此，在从填充ListView的基础ArrayList中删除项目后调用此方法，导致应用程序崩溃。
此外，作为数据源的上述ArrayList存在于扩展Application的Activity中，允许通过app全局访问数据源。
以下是我的代码。任何帮助将不胜感激。
public class CartListAdapter extends ArrayAdapter<Product> {
private ArrayList<Product> products;
//Application context where ArrayList exists for globabal access
final Global globalVariables = (Global) getContext().getApplicationContext();
public CartListAdapter(Context context, int textViewResourceId, ArrayList<Product> products ) {
super(context, textViewResourceId, products);
this.products=products;
}
@Override
public View getView(final int position, View convertView, ViewGroup parent) {
View row = convertView;
prodHolder mainHolder;
final int pos=position;
if(row == null)
{
LayoutInflater inflater = (LayoutInflater) getContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = inflater.inflate(R.layout.activity_cart_row_item, parent, false);
//create holders for listview items
final prodHolder holder = new prodHolder();
holder.txtName = (TextView) row.findViewById(R.id.cart_product_name);
holder.txtAmount= (TextView) row.findViewById(R.id.cart_product_price);
holder.txtQuantity=(TextView) row.findViewById(R.id.cart_quantity_text);
holder.txtRestaurant= (TextView) row.findViewById(R.id.cart_restaurant);
holder.txtType = (TextView) row.findViewById(R.id.cart_type);
holder.txtOption = (TextView) row.findViewById(R.id.cart_option);
holder.plus = (Button) row.findViewById(R.id.cart_increment_quantity);
holder.minus = (Button) row.findViewById(R.id.cart_decrement_quantity);
holder.delete = (Button) row.findViewById(R.id.cart_delete_button);
holder.delete.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
globalVariables.getGlobalProductArrayList().remove(position);
CartListAdapter.this.notifyDataSetChanged();
}
});
//when clicking the plus button in the cart on an item, the cart changes accordingly
holder.plus.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//change quantity when increment button pressed
String quantityTextValue= (String) holder.txtQuantity.getText();
int quantityConvertedInt = Integer.parseInt(quantityTextValue);
int newQuantity= quantityConvertedInt+1;
holder.txtQuantity.setText(newQuantity+"");
//change total amount when increment button pressed
String amountTextValue = (String) holder.txtAmount.getText();
int amountConvertedInt = Integer.parseInt(amountTextValue);
int pricePerItem = amountConvertedInt/quantityConvertedInt;
int newPrice = amountConvertedInt+pricePerItem;
holder.txtAmount.setText(newPrice+"");
//get textviews from holders
Product product = new Product("", 0, 0, "", "", "");
String name = (String) holder.txtName.getText();
String price = (String) holder.txtAmount.getText();
String quantity = (String) holder.txtQuantity.getText();
String restaurant = (String) holder.txtRestaurant.getText();
String mealType = (String) holder.txtType.getText();
String option = (String) holder.txtOption.getText();
//set attributes of temporary product
product.setProductName(name);
product.setProductPrice(Integer.parseInt(price));
product.setProductQuantity(Integer.parseInt(quantity));
product.setRestaurant(restaurant);
product.setProductType(mealType);
product.setProductOption(option);
int cartLength = globalVariables.getMyProductsSize();
//loop through arraylist that exists in global context
for ( int i = 0; i < cartLength; i++) {
Product p = globalVariables.getMyProducts(i);
//if temporary product attributes match the attributes of product in arraylist
if (product.getProductName().equals(p.getProductName())
&& product.getProductType().equals(p.getProductType())
&& product.getProductOption().equals(p.getProductOption()))
//update that products attributes with the new quantity and total price so
// that listview does not refresh values
{
p.setProductQuantity(product.getProductQuantity());
p.setProductPrice(product.getProductPrice());
}
}
}
});
row.setTag(holder);
}
mainHolder = (prodHolder) row.getTag();
//get product stored in array that exists in Application class
Product p = globalVariables.getMyProducts(position);
mainHolder.txtName.setText(p.getProductName());
mainHolder.txtAmount.setText(p.getProductPrice()+"");
mainHolder.txtQuantity.setText(p.getProductQuantity()+"");
mainHolder.txtRestaurant.setText(p.getRestaurant());
mainHolder.txtType.setText(p.getProductType());
mainHolder.txtOption.setText(p.getProductOption());
return row;
}
}
扩展ArrayList的Global类......
public class Global extends Application {
//holds an array of products throughout application life cycle
private ArrayList <Product> myProducts = new ArrayList<>();
//not in use
private Cart cart;
public Cart getCart() {
return cart;
}
public void setCart(Cart cart) {
this.cart = cart;
}
public ArrayList <Product> getGlobalProductArrayList(){
return this.myProducts;
}
public void removeItem (int position){
myProducts.remove(position);
}
//gets the products in the arraylist at the specified position
public Product getMyProducts(int position) {
return myProducts.get(position);
}
//adds a product to the array
public void addMyProducts(Product product) {
myProducts.add(product);
}
//get the size of the array, the amount of products in an array
public int getMyProductsSize (){
return myProducts.size();
}
}
...堆栈跟踪
01-29 23:40:13.992 28953-28953/za.co.clickandeat.clickeatbeta W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x415c0d88)
01-29 23:40:13.992 28953-28953/za.co.clickandeat.clickeatbeta E/test: Exception
01-29 23:40:14.032 28953-28953/za.co.clickandeat.clickeatbeta E/AndroidRuntime: FATAL EXCEPTION: main
Process: za.co.clickandeat.clickeatbeta, PID: 28953 java.lang.IndexOutOfBoundsException: Invalid index 1, size is 1
at java.util.ArrayList.throwIndexOutOfBoundsException(ArrayList.java:255)
at java.util.ArrayList.get(ArrayList.java:308)
at za.co.clickandeat.clickeatbeta.Global.getMyProducts(Global.java:43)
at za.co.clickandeat.clickeatbeta.CartListAdapter.getView(CartListAdapter.java:147) at android.widget.AbsListView.obtainView(AbsListView.java:2240)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1263)
at android.widget.ListView.onMeasure(ListView.java:1175)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.support.v7.internal.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:135)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
at android.view.View.measure(View.java:16643)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2298)
at android.view.View.measure(View.java:16643)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1916)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1113)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1295)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1000)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5675)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:761)
at android.view.Choreographer.doCallbacks(Choreographer.java:574)
at android.view.Choreographer.doFrame(Choreographer.java:544)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:747)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5214)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:814)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:630)
at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
您应该在数组适配器上调用remove（）方法。该参数是要删除的Product对象。
func updateColor()
{
let circle = UIView(frame: CGRect(x: -25.0, y: 10.0, width: 100.0, height: 100.0))
circle.layer.cornerRadius = 50.0;
let startingColor = UIColor(red: (CGFloat(redd1))/255, green: (CGFloat(greenn1))/255, blue: (CGFloat(bluee1))/255, alpha: 1.0)
circle.backgroundColor = startingColor;
addSubview(circle);
//print(redd1);
}
像这样执行删除可确保适配器知道已删除的项目，并通知自己已更改某些内容，从而更新适配器的所有属性。