How could I fill up an array with 1's and 0's based on a user input bit string

Question

I'm currently trying to complete a hw assignment and honestly confused how to even get past this point.

I am supposed to ask the user for a bit string length of 24 that consists of 1's and 0's. I just can't seem to understand how I would go filling up each single array slot with a only 1 value. After I am giving the 24 bit string of 1's and 0's I'm suppose to convert that 24 bit string into 3 separate 8 bit integer components that represent a number from 0-255, which is suppose have a value on the RGB scale.

For example I would take in a bit string of "111111110000000000000000" this would represent "111111111" for red which would be 255, "00000000" for green which would be 0 and "00000000" for blue, so this value would represent pure red.

I'm very stuck on what to do to even start this but I would think its something like this

import java.util.Scanner;
public class Test {
       public static void main(String args[]){
          String[] bitString;
          bitString = new String[24];

          Scanner consuleInput = new Scanner(System.in);
            System.out.println("what is your input bit string?");
            for(int i=0;i < bitstring.length; i++) {
                bitString = consuleInput.nextLine();
                // this was my rough idea on how to go through the array at everyone spot
                // and fill in a 0 or 1 depending on what the giving bitString is
            }

When it comes to splitting the bit string into three components i'm honestly not sure. I would think its something like you take the bit string array of [0] to[7] and assign that to the redValue, [8]-[15] to green and [16]-[23] to blue. with these three split up I would use something like

 int re = Integer.parseInt(redValue, 2);

which would give me the integer value of that string of 1's and 0's from bitString[0] to bitString[7]. I'm just not entirely sure how to implement it.

bgfvdu3w · Accepted Answer · 2017-10-02 00:25:42Z

In your original code, you have a typo in your for loop condition - bitstring should be bitString. You're also trying to assign a String to the entire array (String[]). You need to access the array at a certain index and then assign a value to it.

for (int i = 0; i < bitString.length; i++) {
    bitString[i] = consuleInput.nextLine();
}

However, I propose a better approach. Instead of getting the input one bit at a time, get the whole string and use subtring() to convert every 8 bits to decimal. If needed, you can still implement validation to print an error if the string is not 24 characters long or isn't a binary value.

public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    System.out.println("what is your input bit string?");
    String input = scanner.nextLine();

    int[] rgb = {
        Integer.parseInt(input.substring(0, 8), 2),
        Integer.parseInt(input.substring(8, 16), 2),
        Integer.parseInt(input.substring(16, 24), 2)
    };
}

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