Summary - Array methods

Combine sort, binarySearch and toString to write a sorting tool.

Summary: Array methods

In this group you met five important Arrays methods that work on arrays: sort, toString, binarySearch, copyOf and fill.

They all live in java.util.Arrays. sort and fill modify the array in place; toString and copyOf return new values. binarySearch requires a sorted array.

By combining these methods you can build sort + search + print tools. Now you will write a small sorting tool.

Exercise Sorted list tool

Sort the given scores, print them on one line using Arrays.toString, then look up 72 with Arrays.binarySearch and print the found index.

Show example solution

Arrays.sort(scores);
System.out.println(Arrays.toString(scores));
int i = Arrays.binarySearch(scores, 72);
System.out.println(i);

Test yourself

Which method does not work on an unsorted array?
- Arrays.sort
- Arrays.binarySearch
- Arrays.toString
- Arrays.fill
Show answer

Arrays.sort — binarySearch requires a sorted array; the others do not.

Fill in the blank: array text

int[] nums = {2, 1, 3};
String text = ____.toString(nums);

Show answer

int[] nums = {2, 1, 3};
String text = Arrays.toString(nums);

Match method to return type

Arrays.sort(x)

void
Arrays.toString(x)

String
Arrays.binarySearch(x, v)

int
Arrays.copyOf(x, n)

int[]

Next lesson: ArrayList

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