What could be the issue here ?
I get the following error on compilation:
error: cannot find symbol
.collect(toList())
^
symbol: method toList()
location: class stocks
error: invalid method reference
.map(Stock::getSymbol)
^
cannot find symbol
symbol: method getSymbol()
location: class Stock
Class Stock does have a public method getSymbol
static class StockUtil{
public static Predicate<Stock> isLessThanLimit(Double limit){
return s -> s.tick < limit;
}
public static String toUpperCase(String stock){
return stock.toUpperCase();
}
}
public static void main(String[] args) {
// TODO Auto-generated method stub
List<Stock> stocks = new ArrayList<>(Arrays.asList(new Stock("AMZ",312.0),
new Stock("Yahoo",212.0),
new Stock("ORCL",512.0),
new Stock("SAP",112.0),
new Stock("Google",412.0),
new Stock("FB",12.0),
new Stock("TWT",315.0)));
//print list of stock names below 400 in uppercase
System.out.println(stocks.stream().filter(StockUtil.isLessThanLimit(400.0))
.map(Stock::getSymbol)
.map(StockUtil::toUpperCase)
.collect(toList())
);
2 Answers
Either make sure you use the complete reference to the method as
Collectors.toList()
or import statically
import static java.util.stream.Collectors.toList;
along with a Stock class somewhat as :
class Stock {
String symbol;
...
public String getSymbol() {...} //getter for symbol
...
}
You have not defined the method toList() or you forgot to do static import, try:
import static java.util.stream.Collectors.toList;
no other changes expected in your code.
If you do not want to do static import:
System.out.println(stocks.stream().filter(StockUtil.isLessThanLimit(400.0))
.map(Stock::getSymbol)
.map(StockUtil::toUpperCase)
.collect(Collectors.toList())
);
Refer to java documentation of Collectors for details.
