Conversion of collection to int array

Question

I want to display a graph and for displaying that i need integer values.I get this from my code

    Collection c = Sort.values();

Is there any way that i convert collection in such a way that i get integer values?i get this when i print the collection c

    [64770, 26529, 13028, 848, 752, 496]

score 15 · Accepted Answer · answered May 19 '12 at 11:19

15

Assuming the values are of type Integer, you can try this:

Collection c = Sort.values();
Integer[] a = (Integer[])(c.toArray(new Integer[c.size()]));

answered May 19 '12 at 11:19

For efficiency purposes, can this answer be changed to get a `int[]` instead of `Integer[]`? And was this for an older version of Java before autoboxing? – SimonT Apr 30 '14 at 11:41
@SimonT "can we use `int[]`?" No, not in Java. "was this for Java before autoboxing?" There's no autoboxing in this code (it's not necessary here). Collection could be made generic, but that is not necessary either. – Sergey Kalinichenko Apr 30 '14 at 14:05

score 3 · Answer 2 · answered May 19 '12 at 11:19

3

for (Integer value : c) {
    int i = value.intValue();
    //do something with either value or i
}

answered May 19 '12 at 11:19

Too complicated. Due to autoboxing, you can immediately write: `for (int i : c) {` - no intValue - gymnastics needed. – user unknown May 19 '12 at 12:24
Well that was only to make clear what happens and wasn't sure if wanted an Integer or int. Hence my comment in the code about "do something with either value or i" – Mattias Isegran Bergander May 19 '12 at 12:49

score 2 · Answer 3 · answered Oct 25 '19 at 17:01

2

The question was: conversion to int array
Integer[] can not be assigned to int[] or vice versa

int[] array = c.stream().mapToInt( i -> i ).toArray();

answered Oct 25 '19 at 17:01

Kaplan

score 1 · Answer 4 · answered Apr 30 '14 at 11:14

1

Simply:

Integer[] yourArrayVar = yourCollectionVar.toArray(new Integer[0]);

java just needs to know what kind of array to produce.

answered Apr 30 '14 at 11:14

Amr Lotfy

4 Answers4