Question

1. Create a new ArrayPractice project in Eclipse and a class named ArrayPractice.java.
2. Put everything that follows into the main method except the method arrayAverage.
3. Create a 5 element array of doubles called grades that contains the following numbers in this order: 81.2, 92.5, 48.9, 78.8, and 45.5.
4. Create a 7 element array of ints called numbers that contains the following numbers in this order: 12, 42, 33, 67, 92, 58, and 33.
5. Create a 9 element array of Strings called arguments without using an array initializer.
6. Print (on one line) the length of grades using length.
7. Print (on one line) the length of numbers using length.
8. Print (on one line) the length of arguments using length.
9. Print (on one line) the first element of grades.
10. Print (on one line) the third element of grades.
11. Print (on one line) the last element of numbers.
12. Set the second to last element of grades to be 90.5.
13. Set the third element of numbers to be 99.
14. Set the first six elements of arguments to be "Java", and the rest to be "C++". (HINT: use a loop or two)
15. Use a loop to print each element of grades on the same line, separated by commas (with a trailing comma).
16. Use a loop to print each element of numbers on the same line, separated by spaces (with a trailing space).
17. Use a loop to print each element of arguments on the same line, separated by an underscore (with a trailing underscore).
18. Print the contents of grades using Arrays.toString(grades);
19. Print the contents of numbers using Arrays.toString(numbers);
20. Print the contents of arguments using Arrays.toString(arguments);
21. FINAL STEP: Write a public static method called arrayAverage that takes an array of doubles as a parameter.
22. and returns the average as a double. Print the result of calling arrayAverage with the array grades. with exactly 3 digits after the decimal point.

Answer 1

Length of grades: 5 Length of numbers: 7 Length of arguments : 9 First element of grades: 81.2 Third element of grades: 78.8 Last element of numbers of grades 33 81.2 92.5 48.9 90.5 45.5 12 42 99 67 92 58 33 Java_Java_Java_Java_Java_Java_C++_C++_C++_ 81.2, 92.5, 48.9, 90.5, 45.5], [12, 42, 99, 67, 92, 58, 33] [Java, Java, Java, Java, Java, Java, C++, C++, C++] Average of grades: 71.720

import java.util.Arrays;
import java.util.Scanner;
public class ArrayPractice {

   public static void main(String args[]){
      
       double[] grades ={81.2,92.5,48.9,78.8,45.5};
       int[] numbers ={12, 42, 33, 67, 92, 58,33};
       String arguments[]=new String[9];
      
       System.out.println("Length of grades: "+grades.length);
       System.out.println("Length of numbers: "+numbers.length);
       System.out.println("Length of arguments : "+arguments.length);
       System.out.println("First element of grades: "+grades[0]);
       System.out.println("Third element of grades: "+grades[3]);
       System.out.println("Last element of numbers of grades: "+numbers[numbers.length-1]);
      
       //Set the second to last element of grades to be 90.5.
       grades[grades.length-2]=90.5;
      
       //Set the third element of numbers to be 99.
       numbers[2]=99;
      
       //Set the first six elements of arguments to be "Java", and the rest to be "C++". (HINT: use a loop or two)
       for(int i=0;i<6;i++)
           arguments[i]="Java";
       for(int i=6;i<9;i++)
           arguments[i]="C++";
      
       //Use a loop to print each element of grades on the same line, separated by commas (with a trailing comma).
       for(int i=0;i<grades.length;i++)
           System.out.print(grades[i]+" ");
      
       System.out.println();
      
       //Use a loop to print each element of numbers on the same line, separated by spaces (with a trailing space).
       for(int i=0;i<numbers.length;i++)
           System.out.print(numbers[i]+" ");
       System.out.println();
      
       //Use a loop to print each element of arguments on the same line, separated by an underscore (with a trailing underscore).
       for(int i=0;i<arguments.length;i++)
           System.out.print(arguments[i]+"_");
       System.out.println();
      
       //Print the contents of grades using Arrays.toString(grades);
      
           System.out.print(Arrays.toString(grades)+",");
       System.out.println();
      
       //Print the contents of numbers using Arrays.toString(numbers);
      
           System.out.print(Arrays.toString(numbers)+" ");
       System.out.println();
      
       //Print the contents of arguments using Arrays.toString(arguments);
      
           System.out.print(Arrays.toString(arguments)+"_");
       System.out.println();
      
      
      
       System.out.printf("Average of grades: %.3f\n",arrayAverage(grades));
      
      
      
      
  
   }
   public static double arrayAverage(double []array)
   {
       double sum=0;
       for(int i=0;i<array.length;i++)
       {
           sum+=array[i];
       }
       return sum/array.length;
   }

}