Question

I am trying to get a function in JAVA to take a value in an array as input. Here is my attempt:

public static void main(String[]args)
{
    int [] a = new int [4];
    a[0]=6;
    a[1]=7;
    a[2]=5;
    a[3]=2;
    int g = 11;
    System.out.println calc(a[0], 11);
}
public static int calc(a[], int g)

I am doing this before running a recursion. However, I keep getting an error message. What is the correct way to do this? I want the function, however, to an input from an array. How do I get the function to take not just any int value but rather from the row of a given array?

Answer 1

Change this:

public static int calc(a[], int g)

To this:

public static int calc(int value, int g)

When you do System.out.println(calc(a[0], 11)); you’re actually passing an int to function calc. That int resides in the first position a[0] of the array.

If you want to pass the whole array to calc, your function signature must be:

public static int calc(int[] a, int g)

You’d call it this way:

System.out.println(calc(a, 11));

This line System.out.println calc(a[0], 11); in your code is also wrong. It should be:

System.out.println(calc(a[0], 11));

Suppose your calc function has this:

public static int calc(int value, int g)
{
    return value + g;
}

When you call:

System.out.println(calc(a[0], 11));

The output will be:

17

Why 17? Because you’re summing a[0] = 6 + 11 = 17.

a[0] is a row of the array and you’re actually passing it to the function calc.

In the recursive case, you could have and indexer i for example.

for(int i = 0; i < a.length; i++)
{
     // You could check some condition here:
     // if(a[i] > 10) { System.out.println(calc(a[i+1], 11)); }
     System.out.println(calc(a[i], 11));
}

Now when you execute this code you’ll have this output:

17
18
16
13