Problem Statement: Write a program to make a square and mark out its diagonals. Accept the length as input from the user and give output in the following manner: And ( In simple words, we have printed stars (*) on the boundary positions of the matrix and on the centre positions of the matrix we have printed blank space( ) )   THE CODE: Sample Output: In the above program, two int variables r to accept the length of square as input. On line 7, following statement is used to accept the input from the user: int r = sc . nextInt ();   For taking the input Scanner class has been used, more about Scanner class Algorithm: Two for loops are defined: ·         First for loop with counter variable i has initial value 1, conditional statement i less than or equal to r and an updating statement i++ . ·         Inside the first loop there is a second for loop, with counter variable j has initial value 1, conditional statement j less than or equal to r and an updating

Video Lecture- https://youtu.be/StCjnwfS0NQ Basic structure of a Java program public class xyz { public static void main(String args[]) { //Code //Code //Code //Code //Code }} public - access specifier/modifiers which makes the particular entity accessible throughout the program i.e., it can be accessed by other classes also. static - a keyword by which we don't have to create an object of that particular entity. void- return type keyword by which the function becomes non-returning type. main - name of the function String args[] - argument for main function Print Statement Syntax: System.out.println() ; Three types of Iteration statements are: for loop Example: for(int i=0; i<=5;i++) { //Code //Code //Code //Code //Code } The body of the above for loop will be executed 6 times. while loop( entry control loop) Syntax: while (condition) { //Code //Code //Code //Code //Code } The body of the above while loop will be executed continuously as long as the condition of the while is tr