Exemplo de programa conversor Hexadecimal

package conversor;

import java.util.Scanner;
public class convertendo {
    public static int caso(String stre)
    {
        int guardar=0;
        switch(stre)
        {
            case "a": guardar = 10; break;
            case "b": guardar = 11; break;
            case "c": guardar = 12; break;
            case "d": guardar = 13; break;
            case "e": guardar = 14; break;
            case "f": guardar = 15; break;
            case "A": guardar = 10; break;
            case "B": guardar = 11; break;
            case "C": guardar = 12; break;
            case "D": guardar = 13; break;
            case "E": guardar = 14; break;
            case "F": guardar = 15; break;
            default: guardar = 0; break;
        }
        return guardar;
    }

    public static void main(String[] args) {
        String[] hex = new String[6];
        Scanner in = new Scanner(System.in);
        System.out.println("Entre com o código Hexadecimal");
        hex[0] = in.nextLine();
        hex[1] = in.nextLine();
        hex[2] = in.nextLine();
        hex[3] = in.nextLine();
        hex[4] = in.nextLine();
        hex[5] = in.nextLine();
        int[] numeros = new int[6];

        for(int i=0; i<=5;i++)
        {
            if(caso(hex[i]) != 0)
            {
                numeros[i] = caso(hex[i]);
            } else {
                numeros[i] = Integer.parseInt(hex[i]);
            }
        }
        int[] res = new int[6];
        res[0] = (numeros[0] * 16) + numeros[1];
        res[1] = (numeros[2] * 16) + numeros[3];
        res[2] = (numeros[4] * 16) + numeros[5];

        res[3] = (res[0] * 100) / 255;
        res[4] = (res[1] * 100) / 255;
        res[5] = (res[2] * 100) / 255;
        System.out.println("R (" + res[0] + ")" + " G (" + res[1] + ")" + " B (" + res[2] + ")");
        System.out.println("R (" + res[3] + "%)" + " G (" + res[4] + "%)" + " B (" + res[5] + "%)");

    }

}