使用带有 Java 流的收集和映射时出现“不兼容的类型”错误

Question

I have this class:

public class AirbnbListing {
...
private int price
...
public int getPrice() { return price; }

And I'm trying to use a java stream to collect the integer prices from an ArrayList of AirbnbListing objects:

ArrayList<AirbnbListing> properties = dataParser.getNeighbourhoodProperties(neighbourhood, 0, -1, 0, "All");
ArrayList<Integer> prices =
    properties.stream()
        .map(AirbnbListing::getPrice)
        .collect(Collectors.toList());

But I'm getting "Incompatiable types: inferenance variable R has incompatible bounds". Not sure what the issue is.

Answer 1

Create ArrayList By passing argument like.

ArrayList<Integer> prices =
    properties.stream()
        .map(AirbnbListing::getPrice)
        .collect(Collectors.toCollection(ArrayList::new));//<------- this