我想初始化并将数组放到我的pTotalPrice变量中，以保存产品*数量的总价。我收到了错误。我这样做是因为tablelayout是动态创建的。我需要保留每个产品的价格总价，因此如果我删除了其中一个产品，最终价格会显示正确的值。
错误java.lang.NullPointerException位于pTotalPrice [i] = pPrice * pQuantity;
public class ScreenSecondFragment extends Fragment {
public ScreenSecondFragment(){}
public double pFinalPrice;
public double[] pTotalPrice;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_secondscreen, container, false);
TextView showCartContent = (TextView)rootView.findViewById(R.id.showCart);
final Button thirdBtn = (Button) rootView.findViewById(R.id.third);
//Get Global Controller Class obiect (see application tag in AndroidManifest.xml)
final Controller aController = (Controller) getActivity().getApplicationContext();
// Get Cart Size
final int cartSize = aController.getCart().getCartSize();
/******** Dynamically create view elements - Start **********/
TableLayout ll = (TableLayout) rootView.findViewById(R.id.displayTable);
ll.setStretchAllColumns(true);
ll.setShrinkAllColumns(true);
TableLayout.LayoutParams params = new TableLayout.LayoutParams();
params.setMargins(1, 1, 1, 1);
TableRow.LayoutParams param = new TableRow.LayoutParams();
param.span = 3;
/****** Title header ******/
TableRow rowProdLabels = new TableRow(this.getActivity());
rowProdLabels.setBackgroundColor(android.graphics.Color.BLUE);
// Product column
TextView prodLabel = new TextView(this.getActivity());
prodLabel.setText("PRODUCT");
prodLabel.setTypeface(Typeface.SERIF, Typeface.BOLD);
prodLabel.setTextSize(17);
prodLabel.setTextColor(android.graphics.Color.WHITE);
rowProdLabels.addView(prodLabel);
// Price column
TextView priceLabel = new TextView(this.getActivity());
priceLabel.setText("PRICE");
priceLabel.setTypeface(Typeface.SERIF, Typeface.BOLD);
priceLabel.setTextSize(17);
priceLabel.setTextColor(android.graphics.Color.WHITE);
rowProdLabels.addView(priceLabel);
// Quantity column
TextView quantityLabel = new TextView(this.getActivity());
quantityLabel.setText("Quantity");
quantityLabel.setTypeface(Typeface.SERIF, Typeface.BOLD);
quantityLabel.setTextSize(17);
quantityLabel.setTextColor(android.graphics.Color.WHITE);
rowProdLabels.addView(quantityLabel);
// Total column
TextView totalLabel = new TextView(this.getActivity());
totalLabel.setText("Total Price");
totalLabel.setTypeface(Typeface.SERIF, Typeface.BOLD);
totalLabel.setTextSize(17);
totalLabel.setTextColor(android.graphics.Color.WHITE);
rowProdLabels.addView(totalLabel);
ll.addView(rowProdLabels, params);
/****** Title header end ******/
final TextView finalprice = new TextView(this.getActivity());
if(cartSize >0)
{
for(int i=0;i<cartSize;i++)
{
final int counter = i;
// Get probuct data from product data arraylist
String pName = aController.getProducts(i).getProductName();
double pPrice = aController.getProducts(i).getProductPrice();
int pQuantity = aController.getProducts(i).getProductQuantity();
pTotalPrice[i] = pPrice * pQuantity;
TableRow row= new TableRow(this.getActivity());
row.setBackgroundColor(android.graphics.Color.WHITE);
TextView product = new TextView(this.getActivity());
product.setText(pName+" ");
product.setTextSize(15);
//Add textView to LinearLayout
row.addView(product);
TextView price = new TextView(this.getActivity());
price.setText("RM "+pPrice+" ");
price.setTextSize(15);
//Add textView to LinearLayout
row.addView(price);
TextView quantity = new TextView(this.getActivity());
quantity.setText(pQuantity+" ");
quantity.setTextSize(15);
//Add textView to LinearLayout
row.addView(quantity);
TextView totalprice = new TextView(this.getActivity());
totalprice.setText(String.format("RM %.2f",pTotalPrice[i]));
totalprice.setTextSize(15);
//Add textView to LinearLayout
row.addView(totalprice);
//Update final price
pFinalPrice += pTotalPrice[i];
final int index = i;
Log.i("TAG", "index :" + index);
// Get product instance for index
final ModelProducts tempProductObiect = aController.getProducts(index);
final Button btnRemove = new Button(this.getActivity());
btnRemove.setId(i+1);
btnRemove.setText("Delete");
btnRemove.setOnClickListener(new OnClickListener()
{
@Override public void onClick(View v)
{
if(aController.getCart().checkProductInCart(tempProductObiect))
{
// Product not Exist in cart so add product to
// Cart product arraylist
aController.getCart().removeProducts(tempProductObiect);
pFinalPrice -= pTotalPrice[counter];
finalprice.setText(String.format("RM %.2f",pFinalPrice));
Toast.makeText(getActivity().getApplicationContext(), "Now Cart size: "+aController.getCart().getCartSize(),
Toast.LENGTH_LONG).show();
}
// row is your row, the parent of the clicked button
View row = (View) v.getParent();
// container contains all the rows, you could keep a variable somewhere else to the container which you can refer to here
ViewGroup container = ((ViewGroup)row.getParent());
// delete the row and invalidate your view so it gets redrawn
container.removeView(row);
container.invalidate();
}
});
row.addView(btnRemove);
ll.addView(row,i+1, params);
}
}
/****** Title footer ******/
TableRow rowFinalLabels = new TableRow(this.getActivity());
rowFinalLabels.setBackgroundColor(android.graphics.Color.BLUE);
// Price column
TextView finalPriceLabel = new TextView(this.getActivity());
finalPriceLabel.setText("FINAL PRICE");
finalPriceLabel.setTypeface(Typeface.SERIF, Typeface.BOLD);
finalPriceLabel.setTextSize(17);
finalPriceLabel.setTextColor(android.graphics.Color.WHITE);
rowFinalLabels.addView(finalPriceLabel, param);
//final TextView finalprice = new TextView(this.getActivity());
finalprice.setText(String.format("RM %.2f",pFinalPrice));
finalprice.setTextColor(android.graphics.Color.WHITE);
finalprice.setTypeface(Typeface.SERIF, Typeface.BOLD);
finalprice.setTextSize(17);
//Add textView to LinearLayout
rowFinalLabels.addView(finalprice);
ll.addView(rowFinalLabels);
/****** Title footer end ******/
thirdBtn.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
if(cartSize >0)
{
//Intent i = new Intent(getBaseContext(), ThirdScreen.class);
//startActivity(i);
FragmentTransaction mFragmentTransaction = getFragmentManager().beginTransaction();
mFragmentTransaction.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
mFragmentTransaction.replace(R.id.frame_container, new BillingAddressFragment(), "Cart");
mFragmentTransaction.commit();
}
else
Toast.makeText(getActivity().getApplicationContext(),
"Shopping cart is empty.",
Toast.LENGTH_LONG).show();
}
});
return rootView;
}
}
答案 0 :(得分：1)
在java中，您需要按如下方式初始化数组：
public double[] pTotalPrice= new double[10];
否则
public double[] pTotalPrice;
等于
public double[] pTotalPrice = null;
答案 1 :(得分：1)
在添加元素之前，您需要初始化pTotalPrice：
pTotalPrice=new double[cartSize];