Help with understanding java 'for' loops

Question

I have to write a java program where the solution will include the printing of the arrow tip figure depending on the number of rows. Below are example of how the result shou

Answer 1

I had the same question for a homework assignment and eventually came to a correct answer using a lot of nested if loops through a single for loop.

There is a lot of commenting throughout the code that you can follow along to explain the logic.

class ArrowTip {

public void printFigure(int n) {      //The user will be asked to pass an integer that will determine the length of the ArrowTip
 int half = n/2;   //This integer will determine when the loop will "decrement" or "increment" the carats to String str to create the ArrowTip
 String str = ">";  //The String to be printed that will ultimately create the ArrowTip
 int endInd;        //This integer will be used to create the new String str by creating an Ending Index(endInd) that will be subtracted by 2, deleting the 2 carats we will being adding in the top half of the ArrowTip

 for(int i = 1; i <= n; i++) {       //Print this length (rows)
    System.out.print(str + "\n");   //The first carat to be printed, then any following carats.
    if (n%2==0) {       //If n is even, then these loops will continue to loop as long as i is less than n.
      if(i <= half) {     //This is for the top half of the ArrowTip. It will continue to add carats to the first carat
         str = str + ">>";    //It will continue to add two carats to the string until i is greater than n.
      }
      endInd = str.length()-2;  //To keep track of the End Index to create the substring that we want to create. Ultimately will determine how long the bottom of the ArrowTip to decrement and whether the next if statement will be called.
      if((endInd >= 0) && (i >= half)){   //Now, decrement the str while j is greater than half
         str = str.substring(0, endInd);  //A new string will be created once i is greater than half. this method creates the bottom half of the ArrowTip
      }
    }
    else {          //If integer n is odd, this else statement will be called.
      if(i < half+1) {  //Since half is a double and the integer type takes the assumption of the one value, ignoring the decimal values, we need to make sure that the ArrowTip will stick to the figure we want by adding one. 3.5 -> 3 and we want 4 -> 3+1 = 4
          str = str + ">>"; //So long as we are still in the top half of the ArrowTip, we will continue to add two carats to the String str that will later be printed.
       }
      endInd = str.length()-2;      //Serves the same purpose as the above if-loop when n is even.
       if((endInd >= 0) && (i > half)) {  //This will create the bottom half of the ArrowTip by decrementing the carats.
        str = str.substring(0, endInd);   //This will be the new string that will be printed for the bottom half of the ArrowTip, which is being decremented by two carats each time.
      }
    }
 }
}
}

Again, this was for a homework assignment. Happy coding.