Ivor Horton's Beginning Java™ 2, JDK™ 5th Edition

15.1. Utility Methods for Arrays

The Arrays class in java.util provides you with a set of static methods for operating on arrays. You have methods for sorting and searching arrays, as well as methods for comparing two arrays of elements of a basic type. You also have methods for filling arrays of elements with a given value. Let's look at the simplest method first, the fill() method for filling an array.

15.1.1. Filling an Array

The need to fill an array with a specific value arises quite often, and you already met the static fill() method that is defined in the Arrays class back in Chapter 4. The fill() method comes in a number of overloaded versions of the form:

fill(type[] array, type value)

Here type is a placeholder for the types supported by various versions of the method. The method stores value in each element of array. The return type is void so there is no return value. There are versions supporting type as any of the following:

boolean    byte    char    float    double
short    int    long    Object

Here's how you could fill an array of integers with a particular value:

long[] values = new long[1000];
java.util.Arrays.fill(values, 888L);  // Every element as 888

It's quite easy to initialize multidimensional arrays. To initialize a two-dimensional array, for example, you just treat it as an array of one-dimensional arrays. For example:

int[][] dataValues = new int[10][20];
for(int[] row : dataValues) {
  Arrays.fill(row, 99);
}

This will set every element on the dataValues array to 99. The ...