in java, Write a program that has methods to do the following with arrays: avera
ID: 3572900 • Letter: I
Question
in java, Write a program that has methods to do the following with arrays:
average(double[] array)
*Finds the mean of values in a double array and returns a double containing the mean (average).
swap(String[] array, int x, int y)
*Swaps array elements in a String array at indexes x and y. Returns void.
getRandomIndex(int n)
*Given n, returns a random integer between 0 and n-1 using rand.nextInt(n).
shuffle(String[] array)
*Shuffles a String array elements. Loops n times, where n is the number of elements in the array. For each iteration, calls getRandomIndex for one index, and again for another index, then calls swap with the two random indexes.
printStrings(String[] array)
*Prints a 1D array of String objects. Returns void.
printDouble(double[] array)
*Prints a 1D double array. Returns void.
printDouble(double[][] array)
*Prints a 2D double array. Returns void.
createDouble2D(int n, int m)
*Creates and returns a double array given rows n and columns m. Using nested for loops, fill the array with value of i + j.
main()
*Calls the above methods. Provided in this format below.
import java.util.Random;
public class Lab7c {
static Random rand = new Random(234L);
public static void main(String[] args) {
double[][] d2 = createDouble2D(2,3);
printDouble(d2);
System.out.println();
printDouble(d2[1]);
System.out.println();
double[] d1 = {10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0};
System.out.println(average(d1));
String[] functions = { "absolute", "random", "power", "floor", "sine", "cosine" };
int x = getRandomIndex(functions.length);
int y = getRandomIndex(functions.length);
swap(functions, x, y);
printStrings(functions);
shuffle(functions);
printStrings(functions);
}
/* Add the following methods here:
* average
* createDouble2D
* printStrings
* printDouble // 1D
* printDouble // 2D
* getRandomIndex
* swap
* shuffle
*/
} // end class
Explanation / Answer
Lab7c.java
import java.util.Random;
public class Lab7c {
static Random rand = new Random(234L);
public static void main(String[] args) {
double[][] d2 = createDouble2D(2,3);
printDouble(d2);
System.out.println();
printDouble(d2[1]);
System.out.println();
double[] d1 = {10.0, 11.0, 12.0, 13.0, 14.0, 15.0, 16.0};
System.out.println(average(d1));
String[] functions = { "absolute", "random", "power", "floor", "sine", "cosine" };
int x = getRandomIndex(functions.length);
int y = getRandomIndex(functions.length);
swap(functions, x, y);
printStrings(functions);
shuffle(functions);
printStrings(functions);
}
public static double[][] createDouble2D(int n, int m){
double a[][] = new double[n][m];
for(int i=0; i<n; i++){
for(int j=0; j<m; j++){
a[i][j] = i+j;
}
}
return a;
}
public static void printDouble(double[][] array) {
for(int i=0; i<array.length; i++){
for(int j=0; j<array[i].length; j++){
System.out.print(array[i][j]+" ");
}
System.out.println();
}
}
public static void shuffle(String[] array) {
for(int i=0; i<array.length;i++){
int x = getRandomIndex(array.length);
int y = getRandomIndex(array.length);
swap(array, x, y);
}
}
public static void printDouble(double[] array) {
for(int i=0; i<array.length; i++){
System.out.print(array[i]+" ");
}
System.out.println();
}
public static void printStrings(String[] array) {
for(int i=0; i<array.length; i++){
System.out.print(array[i]+" ");
}
System.out.println();
}
public static int getRandomIndex(int n) {
Random r = new Random();
return r.nextInt(n);
}
public static void swap(String[] array, int x, int y) {
String temp ="";
temp = array[x];
array[x] = array[y];
array[y] = temp;
}
public static double average(double[] array) {
double sum = 0;
for(int i=0; i<array.length; i++){
sum = sum + array[i];
}
return sum/array.length;
}
/* Add the following methods here:
* average
* createDouble2D
* printStrings
* printDouble // 1D
* printDouble // 2D
* getRandomIndex
* swap
* shuffle
*/
} // end class
Output:
0.0 1.0 2.0
1.0 2.0 3.0
1.0 2.0 3.0
13.0
absolute power random floor sine cosine
absolute power cosine floor sine random
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