滚动时 ListView 自定义适配器错误
ListView Custom Adapter error on scrolling
我在下面附上了 listView
自定义适配器的代码,但是当我滚动列表时,我得到了:
mView does not exist, so discard the remaining points.
java.lang.NullPointerException: Attempt to invoke virtual method 'void
android.widget.TextView.setText(java.lang.CharSequence)' on a null
object reference
Can anybody help why I am getting this error it would be very helpfull
public class TransactionAdapter extends BaseAdapter {
private static final String TAG = TransactionAdapter.class.getName();
List<Transacation> arrlist;
Context c;
private LayoutInflater inflater;
public TransactionAdapter(Context context, List<Transacation> list) {
this.arrlist = list;
this.c = context;
inflater = LayoutInflater.from(this.c);
}
@Override
public int getCount() {
return arrlist.size();
}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View result;
final MyViewHolder myViewHolder;
myViewHolder = new MyViewHolder();
final Transacation transacation = arrlist.get(position);
if (convertView == null) {
convertView = inflater.inflate(R.layout.transaction_adapter, parent,
false);
myViewHolder.tv_date = convertView.findViewById(R.id.tv_date);
myViewHolder.tv_status = convertView.findViewById(R.id.tv_status);
myViewHolder.tv_expiry = convertView.findViewById(R.id.tv_expiry);
myViewHolder.tv_amount = convertView.findViewById(R.id.tv_amount);
result = convertView;
convertView.setTag(myViewHolder);
} else {
result = convertView;
}
// myViewHolder.tv_date.setText(""+new java.text.SimpleDateFormat("dd MMM").format(new java.util.Date (transacation.date)));
if(transacation.transactionType.equals("CREDIT")){
myViewHolder.tv_status.setText("Wallet Credited");
myViewHolder.tv_expiry.setText("Expires on " + new java.text.SimpleDateFormat("dd MMM yyyy").format(new java.util.Date (transacation.expiry_date)));
myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#23DD47"));
}
else{
myViewHolder.tv_status.setText("Wallet Expired");
myViewHolder.tv_expiry.setVisibility(View.GONE);
myViewHolder.tv_amount.setText("-₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#FB5151"));
}
return convertView;
}
private class MyViewHolder {
TextView tv_date;
TextView tv_status;
TextView tv_expiry;
TextView tv_amount;
}
}
在我看来,请检查 findViewById 是否具有正确的 ID 名称,或者如果与它无关,请从
更新
myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
至
myViewHolder.tv_amount.setText("+₹" + String.ValueOf(transacation.n_amount));
或者请post完整的日志值
当 convertView 不为 null 时,您需要通过取回标记来构造 ViewHolder,因此将您的 getView()
更改为:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View result;
final MyViewHolder myViewHolder;
final Transacation transacation = arrlist.get(position);
if (convertView == null) {
convertView = inflater.inflate(R.layout.transaction_adapter, parent,
false);
myViewHolder = new MyViewHolder()
myViewHolder.tv_date = convertView.findViewById(R.id.tv_date);
myViewHolder.tv_status = convertView.findViewById(R.id.tv_status);
myViewHolder.tv_expiry = convertView.findViewById(R.id.tv_expiry);
myViewHolder.tv_amount = convertView.findViewById(R.id.tv_amount);
result = convertView;
convertView.setTag(myViewHolder);
} else {
result = convertView;
myViewHolder = (MyViewHolder) convertView.getTag();
}
// myViewHolder.tv_date.setText(""+new java.text.SimpleDateFormat("dd MMM").format(new java.util.Date (transacation.date)));
if(transacation.transactionType.equals("CREDIT")){
myViewHolder.tv_status.setText("Wallet Credited");
myViewHolder.tv_expiry.setText("Expires on " + new java.text.SimpleDateFormat("dd MMM yyyy").format(new java.util.Date (transacation.expiry_date)));
myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#23DD47"));
}
else{
myViewHolder.tv_status.setText("Wallet Expired");
myViewHolder.tv_expiry.setVisibility(View.GONE);
myViewHolder.tv_amount.setText("-₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#FB5151"));
}
return convertView;
}
我在下面附上了 listView
自定义适配器的代码,但是当我滚动列表时,我得到了:
mView does not exist, so discard the remaining points. java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference Can anybody help why I am getting this error it would be very helpfull
public class TransactionAdapter extends BaseAdapter {
private static final String TAG = TransactionAdapter.class.getName();
List<Transacation> arrlist;
Context c;
private LayoutInflater inflater;
public TransactionAdapter(Context context, List<Transacation> list) {
this.arrlist = list;
this.c = context;
inflater = LayoutInflater.from(this.c);
}
@Override
public int getCount() {
return arrlist.size();
}
@Override
public Object getItem(int i) {
return null;
}
@Override
public long getItemId(int i) {
return 0;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View result;
final MyViewHolder myViewHolder;
myViewHolder = new MyViewHolder();
final Transacation transacation = arrlist.get(position);
if (convertView == null) {
convertView = inflater.inflate(R.layout.transaction_adapter, parent,
false);
myViewHolder.tv_date = convertView.findViewById(R.id.tv_date);
myViewHolder.tv_status = convertView.findViewById(R.id.tv_status);
myViewHolder.tv_expiry = convertView.findViewById(R.id.tv_expiry);
myViewHolder.tv_amount = convertView.findViewById(R.id.tv_amount);
result = convertView;
convertView.setTag(myViewHolder);
} else {
result = convertView;
}
// myViewHolder.tv_date.setText(""+new java.text.SimpleDateFormat("dd MMM").format(new java.util.Date (transacation.date)));
if(transacation.transactionType.equals("CREDIT")){
myViewHolder.tv_status.setText("Wallet Credited");
myViewHolder.tv_expiry.setText("Expires on " + new java.text.SimpleDateFormat("dd MMM yyyy").format(new java.util.Date (transacation.expiry_date)));
myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#23DD47"));
}
else{
myViewHolder.tv_status.setText("Wallet Expired");
myViewHolder.tv_expiry.setVisibility(View.GONE);
myViewHolder.tv_amount.setText("-₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#FB5151"));
}
return convertView;
}
private class MyViewHolder {
TextView tv_date;
TextView tv_status;
TextView tv_expiry;
TextView tv_amount;
}
}
在我看来,请检查 findViewById 是否具有正确的 ID 名称,或者如果与它无关,请从
更新myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
至
myViewHolder.tv_amount.setText("+₹" + String.ValueOf(transacation.n_amount));
或者请post完整的日志值
当 convertView 不为 null 时,您需要通过取回标记来构造 ViewHolder,因此将您的 getView()
更改为:
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View result;
final MyViewHolder myViewHolder;
final Transacation transacation = arrlist.get(position);
if (convertView == null) {
convertView = inflater.inflate(R.layout.transaction_adapter, parent,
false);
myViewHolder = new MyViewHolder()
myViewHolder.tv_date = convertView.findViewById(R.id.tv_date);
myViewHolder.tv_status = convertView.findViewById(R.id.tv_status);
myViewHolder.tv_expiry = convertView.findViewById(R.id.tv_expiry);
myViewHolder.tv_amount = convertView.findViewById(R.id.tv_amount);
result = convertView;
convertView.setTag(myViewHolder);
} else {
result = convertView;
myViewHolder = (MyViewHolder) convertView.getTag();
}
// myViewHolder.tv_date.setText(""+new java.text.SimpleDateFormat("dd MMM").format(new java.util.Date (transacation.date)));
if(transacation.transactionType.equals("CREDIT")){
myViewHolder.tv_status.setText("Wallet Credited");
myViewHolder.tv_expiry.setText("Expires on " + new java.text.SimpleDateFormat("dd MMM yyyy").format(new java.util.Date (transacation.expiry_date)));
myViewHolder.tv_amount.setText("+₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#23DD47"));
}
else{
myViewHolder.tv_status.setText("Wallet Expired");
myViewHolder.tv_expiry.setVisibility(View.GONE);
myViewHolder.tv_amount.setText("-₹" + transacation.n_amount);
myViewHolder.tv_amount.setTextColor(Color.parseColor("#FB5151"));
}
return convertView;
}