1. Recursion
Pepper

2. Another way to loop Call yourself repeatedly until you say to stop.
Example:
add up 10 numbers using addUp.
-- Input – number to count
-- Ouput – total of all those numbers added up
Logic:
If the number I am counting is 0, just return 0.
If the number I am counting is anything else, return the number I have + the total of all the rest (the number I have – 1)
Requires:
Trust the function will do its job
A stopper
A way to reach the stopper (decrement or increment)
Code the addUp method and call it to addUp(10)

3. Start by trusting it will work
Create a method that assumes it will do the job it says it will:
Return the number you have + everything else that needed to be done
public static int addUp(int numberToCount) {
// something else will have to be put here
return __________________; }

4. Then, write the stopping code
When should it stop calling itself?
What should it do in that last case?
public static int addUp(int numberToCount) {
if (numberToCount == 1) // stop when you are down to #1
// last called case work
return __________________;}
else
// normal work
return numberToCount + addUp(numberToCount-1); }

5. addUp Solution public class AddUp { public static void main()
System.out.println(addUp(10)); }
public static int addUp(int numberToCount)
if (numberToCount == 1)
return numberToCount;}
else
return numberToCount + addUp(numberToCount-1);

6. Alternative: For public static int addUp(int numberToCount) {
int sum = 0;
for (int count =1; count <= numberToCount;count++)
sum = sum + count; }
return sum;

7. Create a string of stars
YOU TRY:
starString routine
-- Input – number of stars needed
-- Ouput – String of that many stars
Logic:
If the number I am counting is 1, just return 1 star.
If the number I am counting is anything else, return one star + all the rest of the stars (the number I have – 1)
Requires:
Trust the function will do its job
A stopper
A way to reach the stopper (decrement or increment)
Code the starString method and call it to create starString(10)

8. String of Stars public static String starString (int numberStars) {
if (numberStars == 0)
return(""); }
else
return "*" + starString(numberStars-1);

9. Work with shapes
Make a Rectangle keep getting smaller until it is size 5 wide.
The goal is:

10. Work with shapes First code without recursion:
create a method that takes in the size of the square. Code it to return 1 slightly smaller square outline on a square.
Call that method from your main method to see one square on your canvas.

11. Code of just the one square
import javalib.worldimages.*; import java.awt.Color; public class Test7 { public static void main() WorldImage myWorld = printInsideSquares ( 600); myWorld.show(); } public static WorldImage printInsideSquares( int size) WorldImage mainSquare = AImage.makeRectangle(size,size,Mode.OUTLINED); WorldImage littleSquare = AImage.makeRectangle(size/10*9,size/10*9, Color.RED, Mode.OUTLINED); mainSquare = mainSquare.place( littleSquare, size/2, size/2); return mainSquare;

12. Work with shapes Code the base case: Code the recursion:
Add an if statement to return just one square of the given size when the size is < 5.
Code the recursion:
Instead of placing the slightly smaller square on the big square, place a call to your method with that slighly smaller size.

13. Work with shapes import javalib.worldimages.*; import java.awt.Color;
public class Test6
{ public static void main() {
WorldImage myWorld = printInsideSquares ( );
myWorld.show(); }
public static WorldImage printInsideSquares( int size) {
if (size <= 5) {
return AImage.makeRectangle(size,size,Mode.OUTLINED);
else {
WorldImage mainSquare = AImage.makeRectangle(size,size,Mode.OUTLINED);
// WorldImage littleSquare = AImage.makeRectangle(size/2,size/2,Color.RED, Mode.OUTLINED);
mainSquare = mainSquare.place(
printInsideSquares( size/10*9), size/2, size/2 );
return mainSquare;