List of Arrays in Java
What Is the Syntax for Making a List of Arrays in Java? I Have Tried the Following: List a = New List(); and a Lot of Other Things. I Need to Be Able to...
What is the syntax for making a List of arrays in Java?
I have tried the following:
List<int[]> A = new List<int[]>();
and a lot of other things.
I need to be able to reorder the int arrays, but the elements of the int arrays need not to be changed. If this is not possible, why?
Thank you.
3 Answers
Firstly, you can't do new List(); it is an interface.
To make a list of int Arrays, do something like this :
List<int[]> myList = new ArrayList<int[]>();
P.S. As per the comment, package for List is java.util.List and for ArrayList java.util.ArrayList
List<Integer[]> integerList = new ArrayList<Integer[]>();
Use the object instead of the primitive, unless this is before Java 1.5 as it handles the autoboxing automatically.
As far as the sorting goes:
Collections.sort(integerList); //Sort the entire List
and for each array (probably what you want)
for(Integer[] currentArray : integerList)
{
Arrays.sort(currentArray);
}
List is an interface, not a class. You have to choose what kind of list. In most cases an ArrayList is chosen.
List a = new ArrayList();
You've mentioned that you want to store an int array in it, so you can specify the type that a list contains.
List<int[]> a = new ArrayList<int[]>();
While you can have a collection (such as a list) of "int[]", you cannot have a collection of "int". This is because arrays are objects, but an "int" is a primitive.
Elena Rostova holds a Master's degree in Public Health Journalism. She covers groundbreaking medical research, holistic wellness trends, mental health awareness, and nutritional science.
