Declaring, creating and copying arrays; Arrays.sort, binarySearch, compare, mismatch

An array is a fixed-size object holding elements of one type, indexed from 0. The brackets can go after the type or after the name, and this matters in multi-variable declarations: int[] a, b; declares two arrays, while int a[], b; declares one array a and one plain int b. You create an array with a size, new int[5], which fills it with default values, or with an initializer, new int[] {1, 2, 3}. The short form int[] x = {1, 2, 3}; works only in a declaration. Giving both a size and an initializer (new int[3] {1, 2, 3}) or neither (new int[]) is a compile error.