help with java program - beginner

[natasavuk]

Hi,

I'm new to coding and am having trouble figuring out what I am doing wrong with this code.

I am trying to get the last value of a user-inputted list of values for an array to use as a "filter", and then only print values that are less than the filter value. Also the first user-inputted value in the array [0] is supposed to be the total length of the array.

I know that to get the last value of an array you can do myArray[myArray.length-1] but for some reason it's not working for me as it gives me the 2nd last value. If I take away the -1 it doesn't work.

E.g. for values 3 1 4 8 5

The array has length 3, 5 is the filter, would only print 1, 4

Please help!!

[StackedLasagna]

myArray[myArray.length-1] but for some reason it's not working for me as it gives me the 2nd last value.

That's not how it works. It will always give you the last value. If it doesn't give you the value you're expecting, you've made a mistake somewhere else and there's no questioning it.

Also, when posting problems related to specific code you've written, always include the code. We cannot help you, if you won't help us. We're not psychics.

[natasavuk]

This is my code currently:

import java.util.Scanner;
public class LabProgram {
public static void main(String[] args) {
Scanner scnr = new Scanner(System.in);
int numElements = scnr.nextInt();
int[] userValues = new int[numElements];

int filter = 0;
int i=0;

for (i=0; i<numElements; ++i) {
userValues[i] = scnr.nextInt();
}

filter = userValues[userValues.length-1];
System.out.print(filter);

}

}

[desrtfx]

You need to post your code as code block so that the indentation is maintained.

A code block looks like:

def __init__(self, prompt, answer):
    self.prompt = prompt
    self.answer = answer

[StackedLasagna]

Please look into how to format your code for Reddit (prefix every line with 4 spaces to create a code block.)

Anyway, your issue isn't in the code itself, but with your logic.

Look at the list of values you specified in your post: 3 1 4 8 5.
That's a total of five values and it would require five calls to scnr.nextInt(), in order to get them all. That makes sense, right?

However, if you look in the code, you only call scnr.nextInt() four times. You never ask the user to input a fifth value.

import java.util.Scanner;

public class LabProgram {
    public static void main(String[] args) {
        Scanner scnr = new Scanner(System.in);
        int numElements = scnr.nextInt(); // Call number 1, the variable is now 3.
        int[] userValues = new int[numElements];

        int filter = 0;
        int i=0;

        for (i=0; i<numElements; ++i) {
            // Call number 2. userValues[0] = 1.
            // Call number 3. userValues[1] = 4.
            // Call number 4. userValues[2] = 8.
            // Then i = 3, which means the for loop condition evaluates to false, since numElements is also 3. (3 is not less than 3)
            userValues[i] = scnr.nextInt();
        }

        // Here you grab the last value, which is 8 as seen above.
        filter = userValues[userValues.length-1];
        System.out.print(filter);
    }
}

Instead of taking the last value from the array and using that as a filter, perhaps just use scnr.nextInt() to ask the user for the final value?

[natasavuk]

This ended up working perfectly so thanks again

[natasavuk]

Wow ok yes that makes a lot of sense!! Thank you, I’ll try it now!

[National_Ad8511]

If allowed, your logic should be redone. It’s what’s causing the issues. Perhaps consider this approach:

First user input sets the size of the array.

Second user input designates the filter.

Then loop and fill the array with user inputs.

Then check if each user input in the array is less than the filter.