/**
 * This activity will walk you through writing basic code in Java. You will see how to define methods,
 * work with different data types, write conditionals, write loops, and work with arrays. We will not
 * work with any more advanced class features of Java
 * 
 * Read the file from the top down. Some problems will have prewritten code. Make sure you
 * read and understand what each line is for and doing, and ask questions if you do not understand.
 */
public class JavaBasics {
    

    /*
     * Each problem in this activity will be a different method. This main class
     * runs the methods defined in each problem so that you run the file and see what your code does.
     * When you have completed a problem, uncomment out that respective problem's print statement.
     */
    public static void main(String[] args) {
        // System.out.println("Problem 0: " + problem0());
        // System.out.println("Problem 1: " + Integer.toString(problem1()));
        // System.out.println("Problem 2: " + Integer.toString(problem2(3, 5)));
        // System.out.println("Problem 3: " + problem3());
        // System.out.println("Problem 4: " + problem4());
        // System.out.println("Problem 5: The 3rd through 9th characters of \"Hamburglar!\" are " + problem5("Hamburglar!"));
        // System.out.println("Problem 6: " + problem6(1));
        // System.out.printf("Problem 7: 1 is %s, 2 is %s, 3 is %s, and 6 is %s \n", problem7(1), problem7(2), problem7(3), problem7(6));
        // System.out.println("Problem 8: The numbers from 1 to 20 sum to " + problem8(20));
        // System.out.println("Problem 9: Racecar backwards is " + problem9("Racecar"));
        // System.out.println("Problem 10: The default int array with 5 elements is " + problem10(5));
        // System.out.println("Problem 11: Your explicit array was " + Arrays.toString(problem11()));
        // System.out.println("Problem 12: The integers in {5, 6, 2, 3} sum to " + problem12(new int[] {5, 6, 2, 3}));
        // System.out.println("Problem 13: The numbers 1 to 5 are " + Arrays.toString(problem13(5)));
        // System.out.println("Problem 14: The numbers from 1 to 20 still sum to " + problem14(20));
    }



    /*
     * Problem 0 : How This Activity Works
     * In order to avoid compile errors, most problem methods in this file
     * throw an UnsupportedOperationException. When working on a specific problem
     * delete the line throwing the exception and uncomment the return statement below it.
     */
    private static String problem0() {
        // Remove the line below
        throw new UnsupportedOperationException("Remove This Line and Uncomment The Return Below");
        
        // Uncomment the line below (delete the // symbol)
        // return "I did it!";

        // Don't forget to uncomment the print statement in main for this problem!
        // Run the program to make sure it prints out "I did it!"
    }



    /*
     * Problem 1 : Declaring Variables
     * This method will show you how to declare variables
     * This method should output the number 12. Follow the instructions below.
     */
    private static int problem1() {
        int a; //Declares that the variable a exists and is an int. a becomes the default int value of 0
        a = 5; //Reassigns a to be 5
        // We can do this all on one line:
        // int a = 5;

        // Declare an int variable named b below, assign it a value so that this function returns 12.
        // Do this all on one line. Then you can uncomment the return statement.



        
        throw new UnsupportedOperationException("Remove This Line");
        // return a + b;

        // Don't forget to uncomment the print statement in main for this problem!
    }


    /*
     * Problem 2 : Method Arguments
     * We can declare variables in a method's signature. These are the inputs to the function
     * and are usable within the method body. This method currently takes in one input, an integer,
     * that is referred to in the body of the code as c.
     * 
     * Add a second int input named d to this method. If you run the file after removing
     * the exception and uncommenting the return and the call in main it should print "8"
     */
    private static int problem2(int c) {

        throw new UnsupportedOperationException("Remove This Line");
        // return c + d;
    }




    /*
     * Problem 3 : Method Return Type
     * 
     * The type listed before the method name is the return type of the function.
     * When we call a method, we get something of the return type back.
     * Add a return statement to this method and return anything you want of it's return type.
     */
    private static String problem3() {
        throw new UnsupportedOperationException("Remove This Line");

    }





    /*
     * Problem 4 : Calling Methods
     * 
     * We can call methods defined in a file inside of other methods we write. We do this by simply
     * writing their name.
     * 
     * We can call public methods defined in other files by using the . operator, either:
     * 1) If the method is not static, we use . after the specific instance of that type (e.g. "Hello".charAt(5))
     * 2) If the method is static, we use . after the class name (e.g. )
     * 
     * In this problem we will call the method you defined above, and return a String
     * This String will be the number of characters in the string cubed.
     * For example, if problem3() returned "Banana!", problem4() would return "343" since
     * "Banana!" has 7 characters, and 7^3 = 343. Notice "343" is a String, not an int.
     * 
     * 
     */
    private static String problem4() {
        // Call your problem3() method and assign it to a String variable called p3
        
        // Call the instance (non-static) length() String method on p3, assign it to a variable numChars
        
        // Call the static pow() method of the Math class on numChars to cube it. Assign thi value
        // to a variable named numCubed. You can hover over pow to read the documentation, 
        // or you can go to https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/lang/Math.html
        // You will get back a double (decimal). You need to cast it to an int by writing (int), e.g.
        // int example = (int) 5.6;



        throw new UnsupportedOperationException("Remove This Line");

        // We use the static method toString() of the Integer class to convert an int to a String
        //return Integer.toString(numCubed); 
    }

    /*
     * Problem 5: Declaring your own method
     * 
     * Write your own private static method named problem5() that takes in a String and returns a String. 
     * The output String will be the 3rd through 9th characters of the input. You should look in the String
     * class documentation for the method substring to help you do this.
     * 
     * For example problem5("0123456789") will return "2345678".
     * Remember that the index of the 1st character of a String is 0.
     * Pay attention to which indexes of substring are inclusive vs exclusive
     * 
     * Read the String documentation (https://docs.oracle.com/en/java/javase/24/docs/api/java.base/java/lang/String.html)
     * to find a method to help you do this.
     */

    // Declare your own method here as described above





    /*
     * Problem 6 : Conditionals
     * 
     * In this problem we will see how to use conditionals. This method should return
     * "Galinda" if the method is given an even int and "Elphaba" an odd int.
     * 
     */

    private static String problem6(int n) {
        // The syntax for a basic if-else conditional is
        // if (condition) {
        // ...
        // } else {
        // ..
        // }
        // where condition is whatever Boolean condition you want
        
        // The below code always returns Galinda. Replace true with
        // a condition to check whether n is even or odd.
        // Even numbers are multiples of 2, and remember we can use modulo (%) to
        // check if a number is a multiple of another.

        if (true) {
            return "Galinda";
        } else {
            return "Elphaba";
        }

        // If you do this correctly, Elphaba should print when run.
        // In the void method, try changing the input to problem6 to get it to print Galinda again.
    }

    /*
     * Problem 7 : else if
     * We can make more complicated conditionals with else if statements.
     * 
     * A number is "threeven" if it is divisible by 3. Write a private static method called problem7
     * that, given an int, returns the String "even" if the input is is even, "threeven" if it is divisible by 2, 
     * "both" if it is both even and threeven, and "neither" if it is neither.
     * 
     * You will need to use ``else if" in conjunction with the Boolean operators && (and), || (or), and ! (not):
     * 
     * if () {
     *  ...
     * } else if () {
     *  ...
     * } else {
     *  ...
     * }
     * 
     * You can chain as many else ifs as you want!
     */

     // Write your method problem7() here





    /*
     * Problem 8 : For Loops
     * 
     * To write a for loop in java we have to follow a specific syntax:
     * 
     * for (statementA ; statementB ; statementC) {
     *  ...
     * }
     * 
     * Where:
     * statementA is a declaration of a loop variable
     * statementB is a condition involving the loop variable
     * statementC is an update to the loop variable that occurs at the end of the iteration
     * 
     * Finish the method below, which when given the int n, sums the numbers from 1 to n.
     * For example, problem8(9) = 45, since 1 + 2 + 3 + ... + 9 = 45
     *
     */
    public static int problem8(int n) {
        int output = 0; // this variable will be our output

        for (int i = 1; i <= n; i = i + 1) {
            // Add code here to sum up the numbers
            // When the loop starts, i = 1 and we should add 1 to output
            // At the next loop iteration, i = 2, and so we should add 2 to the output

        }

        // Make sure you understand what each part of the for loop declaration is doing!

        return output;
    }

    /*
     * Problem 9 : Loops over Strings
     * 
     * Finish the method below which reverses the input.
     * For example, problem9("Banana") outputs "ananaB" 
     * You just need to declare the loop, your temp variable should be called i
     */
    public static String problem9(String s) {
        String output = ""; // the output string will start as the `empty string', the string with no characters

        // Write a for loop that starts at the end of the works backwards.

        // Hint 1: How do you start at the end of the string? 
        // Hint 2: When do you stop the loop?
        // Hint 3: How does your loop variable change after every iteration?

        // Remember that the 1st character of a string is at position 0
        // The last character of a string is at position n-1, where n is the string's length

        // Use the following to concatenate the characters as you go.
        // output = output.concat(s.charAt(i))


    
        return output;
    }

    /*
    * Problem 10 : Declaring Arrays
    * 
    * In Java we can declare an array of any type by writing [] after the name of the
    * Type.
    *
    * Follow the comments to finish the method below, which returns the String representation of
    * a default int array of length n
    */
    private static String problem10(int n) {
        // Declare and initialize a default int array variable named arr of size n
        // Remember we use the new command to initialize a default array
        // e.g. new String[i]; initializes a default String array of size i



        throw new UnsupportedOperationException("Remove This Line");

        // Arrays.toString() above converts arr into a readable String
        // The method arr.toString() returns gibberish
        // To use it we must first write:
        // import java.util.Arrays;
        // at the top of this file

        //return Arrays.toString(arr); 

    }

    /*
     * Problem 11 : Declaring Arrays Explicitly
     * 
     * Using "new arr[i];" to declare an array fills the array with default values
     * We can explicitly provide values using {} 
     * 
     * For example,
     * int[] example = {1, 2, 3, 4};
     * Or if we are not assigning it to a variable:
     * new int[] {1, 2, 3, 4};
     */
    private static String[] problem11() {
        // Declare an initialize a String array named arr that contains four Strings of your choosing.



        throw new UnsupportedOperationException("Remove This Line");
        // return arr;
    }

    /*
     * Problem 12 : Accessing Arrays
     * 
     * We access the (i+1)th element of an array by writing [i] after the name of the array.
     * Finish the method below that sums the values of an int array
     * For example problem12({3, 2, 3, 4}) returns 12 since 3 + 2 + 3 + 4 = 12
     */
    private static int problem12(int[] arr) {
        int output = 0;

        // Write a for loop that "traverses" the array from the beginning to end
        // Inside your loop, access the stored value at that position and increase output by that amount
        // Remember that you use .length to get the length of an array (no parentheses)




        return output;
    }

    /*
     * Problem 13 : Assigning Values to Arrays
     * 
     * We assign values to an array by accessing them and using =. For example,
     * arr[3] = 10;
     * makes the 4th element of arr 10
     * 
     * Write a private static method named problem13 that, given an int n, returns an int array of length n whose elements
     * are 1, 2, 3, ... n
     * 
     * Declare an int array named output and initialize it as a default array of the correct size.
     * Use a for loop to loop through the entries of output and replace the 0s with the correct value
     * After your loop, return output
     */

    // Write your code here:





    /*
     * Problem 14 : Combining Methods
     * 
     * Use the methods problem12() and problem13() to finish the method below
     * This method will do the same as problem8, which when given int n,
     * outputs the sum of the numbers from 1 to n.
     * 
     */

    private static int problem14(int n) {

        throw new UnsupportedOperationException("Remove This Line");
    }

}