List of Arrays in Java

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.