CODEWITHSUNDEEP
java
Finding Nemo
Finding Nemo

Reputation: 129

Creating a list from size

I know this is easy and can be done with 2 lines of code, but i am curious to know if there exists any such function i have a int which tell me the size of list and i need to create a list say

List<Integer> intList;

i can create this by easily iterating through the size something like

for(int i=1 ; i <= size; i++)  // started with 1 as i want it from 1
{
  fill list
}

but i was just thinking as if there exists any such methods either in Collection API or Apache common where i can pass the size to get a List with given size

Edit

May i was not able to put question in proper way, i want to get filled my list say if size=4 than i was thinking abt something

Integer=1
Integer=2
Integer=3
Integer=4

and not an empty list with size 4

i know question do not make much sense, but still its better to clear your questions

Upvotes: 0

Views: 181

Answers (3)

Peter Ilfrich
Peter Ilfrich

Reputation: 3816

Short answer: No

The two-liner you're currently using is already optimal.

Upvotes: 2

Jesper
Jesper

Reputation: 206876

To answer the question after what you've added with your edit: No, there's no such method to fill a list with ascending integers in the standard collections API. You'll have to program a loop yourself and add elements to the list.

Upvotes: 0

Minion91
Minion91

Reputation: 1929

The thing here is that List is an interface class and you can't create instances of an interface class. So before you want to construct it you need to know what kind of List you want to create. For the moment let's assume you want an ArrayList. From this moment on you can simply use the correct constructor to initialize your list e.g.

List<Integer> intList = new ArrayList<Integer>(10);

Which constructs an ArrayList of initial capacity 10.

For other kinds of list you can check the Java documentation.

To fill the list with initial data you can do something like this:

int[] myArray = new int[]{ 58,63,67,72,70,63,62,63 };
List<Integer> intList = new ArrayList<Integer>(myArray );

Upvotes: 0

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