# static methods

write static methods as follows:

• double sum(double[] a) – returns the sum of the entries in the array a.

• double[] fill(int n, double v) – returns an array of n doubles, all of whose values are v.

• double[] random (int n) – return an array of n random doubles.

• double min(double[] a) – returns the minimum element of the array a.

• double max(double[] a) – returns the maximum element of the array a.

• double average(double[] a) – returns the average (or mean) of the elements of the array a.

• double variance(double[] a) – returns the variance of the elements of the array a (note: this

method should call your average method).

• double stdDev(double[] a) – returns the standard deviation of the elements of the array a (note:

this method should call your variance method).

• double[] read() – reads an array from the keyboard and returns it (read the number of elements

first, and then that many numbers).

• void print(double[] a) – prints an array, a, on a single line with commas between elements (do

NOT use Arrays.toString()).

Write a Main class with a main method that tests your methods appropriately (i.e. by calling each

method at least once with various inputs), and printing the results.

Question 2

Consider the following method and method call:

public static int inc(int a) {

a++;

return a;

}

int a = 10;

int b = inc(a + 12);

int c= inc(a);

System.out.println(a);

System.out.println(b);

System.out.println(c);

What is the output from this code? Carefully explain your answer (i.e. carefully show how the method

inc is called).

Question 3

Consider the following method and method call:

public static int[] inc(int[] a) {

a[0]++;

return a;

}

int[] a = { 10, 20, 30, 40 };

int[] b = inc(a);

System.out.println(b[0]);

System.out.println(a[0]);

What is the output from this code? Carefully explain your answer (i.e. carefully show how the method

inc is called).

Question 4

Consider the following code:

int[] a = { 10, 20, 30, 40 };

int[] b = a;

int[] c = { 10, 20, 30, 40 };

System.out.println(a == b);

System.out.println(a == c);