Basically I have an ArrayList of locations:
ArrayList<WorldLocation> locations = new ArrayList<WorldLocation>();
below this I call the following method:
.getMap();
the parameters in the getMap() method are:
getMap(WorldLocation... locations)
The problem I'm having is I'm not sure how to pass in the WHOLE list of locations
into that method.
I've tried
.getMap(locations.toArray())
but getMap doesn't accept that because it doesn't accept Objects[].
Now if I use
.getMap(locations.get(0));
it will work perfectly... but I need to somehow pass in ALL of the locations... I could of course make keep adding locations.get(1), locations.get(2)
etc. but the size of the array varies. I'm just not use to the whole concept of an ArrayList
What would be the easiest way to go about this? I feel like I'm just not thinking straight right now.
Source article: Passing a list as an argument to a vararg method
Use the toArray(T[] arr)
method.
.getMap(locations.toArray(new WorldLocation[0]))
Here's a complete example:
public static void method(String... strs) {
for (String s : strs)
System.out.println(s);
}
...
List<String> strs = new ArrayList<String>();
strs.add("hello");
strs.add("world");
method(strs.toArray(new String[0]));
// ^^^^^^^^^^^^^^^^^^^^^^^^^^^
...
In Java 8:
List<WorldLocation> locations = new ArrayList<>();
.getMap(locations.stream().toArray(WorldLocation[]::new));
locations.toArray(WorldLocations[]::new)
also seems to works since java 11 (Without the .stream()
)
IntFunction
, which was added in Java 11 :) docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/…
A shorter version of the accepted answer using Guava:
.getMap(Iterables.toArray(locations, WorldLocation.class));
can be shortened further by statically importing toArray:
import static com.google.common.collect.toArray;
// ...
.getMap(toArray(locations, WorldLocation.class));
List
s, but couldn't instantiate a generic array in order to use Array.toArray
.
List.toArray
You can do:
getMap(locations.toArray(new WorldLocation[locations.size()]));
or
getMap(locations.toArray(new WorldLocation[0]));
or
getMap(new WorldLocation[locations.size()]);
@SuppressWarnings("unchecked")
is needed to remove the ide warning.
Though it is marked as resolved here my KOTLIN RESOLUTION
fun log(properties: Map<String, Any>) {
val propertyPairsList = properties.map { Pair(it.key, it.value) }
val bundle = bundleOf(*propertyPairsList.toTypedArray())
}
bundleOf has vararg parameter
java
Success story sharing
someMethod(someList.toArray(new ArrayList<Something>[someList.size()]))
will give you a warning that is very annoying if the function is more than a few lines long (because you can either suppress it for the whole function or you have to create the array in an additional step and suppress the warning on the variable you store it.