I have this program compiling and running but it only calculates the mean of each row. I have tried several changes and nothing works. How do I get it to calculate the mean of all grades.

import java.util.Scanner;

public class GradeBook
{
private String courseName;
private int grades[][];


public GradeBook( String name, int gradesArray[][])
{
courseName = name;
grades = gradesArray;
}

public void setCourseName( String name )
{
courseName = name;
}

public String getCourseName()
{
return courseName;
}


public void processGrades()
{
outputGrades();

System.out.printf ("\n%s %d\n%s %d\n\n",
"The minimum grade is ", getMinimum(),
"The maximum grade is ", getMaximum());


}

public int getMinimum()
{
int lowGrade = grades[ 0 ][ 0 ];

for ( int studentGrades[] : grades )
{
for ( int grade : studentGrades )
{
if ( grade < lowGrade )
lowGrade = grade;
}
}
return lowGrade;
}
public int getMaximum()
{
int highGrade = grades[ 0 ][ 0 ];

for ( int studentGrades[] : grades )
{
for ( int grade : studentGrades )
{
if ( grade > highGrade )
highGrade = grade;
}
}
return highGrade;
}

public double getMean( int setOfGrades[] )
{
int total = 0;

for (int grade : setOfGrades )
total += grade;

return (double) total + setOfGrades.length;
}


public void outputGrades()
{
System.out.println( "The grades are:\n" );
System.out.print(" " );


for ( int test = 0; test < grades[ 0 ].length; test++ )
System.out.printf( "", test + 1 );

System.out.println("" );

for ( int student = 0; student < grades.length; student++ )
{

for ( int test : grades[ student ] )
System.out.printf( "%8d", test );

double mean = getMean( grades[ student ] );
System.out.printf( "%9.2f\n", mean );
}
}
}



public class GradeBookTest
{
public static void main( String[] args)
{
int gradesArray[][] = { {88,99,89,88,77},
{98,75,66,89,65},
{90,89,70,78,100},
{94,74,86,89,63},
{99,76,66,89,64},
{89,76,89,88,56},
{98,76,89,88,99},
{98,89,66,88,89} };

GradeBook myGradeBook = new GradeBook(
"", gradesArray);
myGradeBook.processGrades();
}
}

Your program is only outputting the mean for each single array because that is all that you are telling it to do.



In this method, you only give access to a one dimensional array, so there is no way to get the mean of the entire 2d array. To fix this, make the method accept a 2d array then use a nested for loop in the method.

Something like this maybe: