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I'm new to Java so I have given myself small projects to help myself learn the ropes of java. My project was to create a function that would summate an expression no matter how high the degree or value of n.

I ended up being able to complete it but I wanted someone who knew what they were doing to look over it and see if I was doing things the right way.

A goal was to use no pre-built packages but I ended up using the java.lang.Math.pow() function (I didn't import it).

Also, what recommendations do you have for learning for beginners? I do have some experience programming but I feel like I never learned the correct way...

Code:

package TestSpace;
public class MathClass {
    
/*
    Steps:
    1. Get array of any length and n
    2. Reverse list so highest degree coefficients are last
    3. Run for loop for each time n increases
    4.Run for loop inside of that for each entry in array
*/
        
    //args consists of the coefficients of x; must include all degrees of x counting down from the highest degree
    public static float sigma (int[] args, int n) {
        float value = 0;
        int length = args.length;
        //reverses list
        int[] reverselist = reverselist(args);
            
        for(int i = 1;i<n+1;i++) {
            
            for(int v = 0; v < length;v++) {
                // Multiplies coefficient by "x" raised to the power of its degree
                value += reverselist[v] * java.lang.Math.pow(i, v);
            }
        }
        return value;
    }
    
//Reverses the order of the given array so that highest degree is at the end
    public static int[] reverselist(int[] args) {
        int length = args.length;
        int[] newint = new int[length];
        for(int i = 0;i<length;i++) {
            newint[i] = args[length - (i+1)];       
        }
        return newint;
    }
        
//Makes printing simple
    public static void print(Object obj) {
        try {
            System.out.println(obj);
        }catch(Exception e){
            System.out.println(e);
        }       
    }
    
    //main function
    public static void main(String[] args) {
        print(sigma(new int[] {5,2,7,4},4));
    }
}
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  • \$\begingroup\$ That print is not making printing simple. Which exeption you are triing to catch? \$\endgroup\$
    – convert
    Feb 7, 2022 at 23:33

1 Answer 1

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  1. Follow Java naming conventions. Your package name should be all lowercase - 'testspace'. 'reverselist' should be 'reverseList'.
  2. Don't use fully qualified 'java.lang.Math', just 'Math'. You don't need to import classes from the java.lang package.
  3. Indent your comments to match the code.
  4. Use descriptive variable names, e.g. 'v' could be 'exponent' or 'power'. Why use 'i' and then describe it as 'x' in the comment? Should 'reverselist' be 'reverseArray'?

In general your algorithms are reasonable.

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