Array Utilities

Introduction

In this exercise you will practice

• writing methods,
• using classes from the Java Standard Library, and
• working with arrays.

Problem Description

You find yourself needing to do things with arrays frequently, such as getting subarrays from them, determining equality, concatenating them, and printing them.

Solution Description

Write a class called ArrayUtil with the following methods:

• public static int[] take(int n, int[] xs) which returns a new array containing the first n elements of xs
• public static int[] drop(int n, int[] xs) which returns a new array containing the last n elements of xs
• public static boolean equals(int[] xs, int[] ys) which returns true if xs.length == ys.length and xs[i] == ys[i] for 0 <=i < xs.length
• public static int[] concat(int[] xs, int[] ys) which returns a new array containing the elements of ys after the elements of xs
• public static String toString(int[] xs)
• public static String toString(int[][] as)
• public static int[][] identity(int n) which returns an n x n identity matrix

Tips and Considerations