Arrays.sort
- Java course
- Beginner
- Lesson 59/116
- 4 min
Learn sorting with Arrays.sort.
Sorting with Arrays.sort
In Java, the easiest way to sort an array from smallest to largest is the Arrays.sort method. It sorts the array in place: it does not return a new array, it rearranges the elements of the existing one.
int[] scores = {78, 92, 55};
Arrays.sort(scores);
// scores is now: {55, 78, 92}The method orders the array in ascending order. For binary search, which you will see later, the array must be sorted first.
Sorting and binary search
Some methods require a sorted array. Arrays.binarySearch is one of them: for fast lookup it requires the array to be sorted.
If the array is not sorted, binarySearch may return a wrong result; that is why you call Arrays.sort first.
int[] nums = {4, 2, 7, 1};
Arrays.sort(nums);
int i = Arrays.binarySearch(nums, 4);
// i = 2Sorting also moves the smallest and largest values to the ends of the array, which makes further processing easier.
Practice Sort and print the scores
Sort the scores below from smallest to largest and print each one on its own line.
Starter code
public class Main {
public static void main(String[] args) {
int[] scores = {78, 92, 55, 64, 88};
// Sort the scores from smallest to largest
// Print each score on its own line
}
}Sample solution
Arrays.sort(scores);
for (int s : scores) {
System.out.println(s);
}Expected output
55 64 78 88 92
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What happens after calling Arrays.sort(scores)?
int[] scores = {78, 92, 55};
Arrays.sort(scores);- It causes a compile error because Arrays.sort rejects int[]
- The scores array stays unchanged and a sorted copy is returned
- A new int[] is returned and scores stays the same
- The scores array is sorted in place and returns no value Correct answer
Explanation: Arrays.sort is a void method; it sorts the array in place.
2 Fill in the blank: sort the array
int[] nums = {9, 3, 7};
____;
System.out.println(nums[0]);int[] nums = {9, 3, 7};
Arrays.sort(nums);
System.out.println(nums[0]);Explanation: The Arrays.sort(nums) call sorts the array.
3 Match method to behavior
| Term | Meaning |
|---|---|
Arrays.sort(x) |
Sorts the array in place |
Arrays.toString(x) |
Converts the array to text |
Arrays.binarySearch(x, v) |
Searches a value in a sorted array |
Arrays.copyOf(x, n) |
Takes a copy of the array |