How to pass an ArrayList to a varargs method parameter

Question

Basically I have an ArrayList of locations   ArrayList lt WorldLocation gt  locations   new ArrayList lt WorldLocation gt       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

User · Answer

In Java 8   List lt WorldLocation gt  locations   new ArrayList lt  gt       getMap locations stream   toArray WorldLocation    new

User · Answer

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

User · Answer

Source article  Passing a list as an argument to a vararg method  Use the toArray T   arr  method   getMap locations toArray new WorldLocation locations size        toArray new WorldLocation 0   also works  but you would allocate a zero-length array for no reason    Here s a complete example  public static void method String    strs        for  String s   strs          System out println s              List lt String gt  strs   new ArrayList lt String gt         strs add  quot hello quot        strs add  quot world quot             method strs toArray new String strs size

User · Answer

Though it is marked as resolved here my KOTLIN RESOLUTION fun log properties  Map lt String  Any gt         val propertyPairsList   properties map   Pair it key  it value        val bundle   bundleOf  propertyPairsList toTypedArray       bundleOf has vararg parameter

User · Answer

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

[java] How to pass an ArrayList to a varargs method parameter?

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