Java Feeling Loopy Cheat Sheet

Feeling Loopy

While Loop:

    Psuedo-Code:  //simple

    anyQuestions = ask "Are there any questions?"
    while anyQuestions
        answers the questions
        anyQuestions = ask "Any more questions?"

    next slide //steps out and goes to the next slide


Do-While Loop: like a While Loop, do the stuff in bracket at least once.

do { //at least once }
while ();


        Random random = new Random();
        int numberOfPutts = 0;           //<- the counter
        boolean ballInHole = false;      //<- ball is !ballInHole until we get the ball in hole. //simple

        // Do-While loop
        do {
            System.out.println("Action: Putts ball");

            ballInHole = random.nextBoolean();

            numberOfPutts++; //<-- increment counter

        } while (!ballInHole);      //basically loop until the ball goes into the hole.

        System.out.println("you got the ball in " + numberOfPutts);



For Loop: use when you know the # times you want to loop.  An old school way of looping through an Array.

    Psuedo-Code: 99 Bottles of Beer on the Wall

    for (initialize; check condition if True; increment) {
       println(i + "how many bottles of beer on the wall")
    }

    // Real code
    for (int i = 99; i > 0 ; i--) {
        System.out.println(i + " bottles of beer on the wall, take one down, pass it around...");
    }




Arrays: used to store many objects of the same type in a single variable.

   >Use a for loop to print out each Jackson in the JacksonFive Array

        String[] jacksonFive = {"Michael", "Jackie", "Tito", "Jermaine", "Marlon", "Randy"};
        for (int i = 0; i < jacksonFive.length; i++){
            //pull out a jackson
            String jackson = jacksonFive[i];
            System.out.println("Jackson: " + jackson);
        }


^So that is the old way of doing it, its not-so-good pratice now in JAVA although other programming languages still use it.
>Now we use... *drum roll please*

For-Each loop aka "for-in" loop: cleaner, faster.


        String[] jacksonFive = {"Michael", "Jackie", "Tito", "Jermaine", "Marlon", "Randy"};
        for (String jackson : jacksonFive){
            //pull out a jackson
            System.out.println("Jackson: " + jackson);
        }

// When you see the colon (:), read it as “in.” Thus, the loop above reads as “for each String jackson in jacksonFive.”





Practice complex loop examples.

Jim has three tries (ball throws) to get Craig in the dunk tank.

//While Loop method:

        Random random = new Random();
        boolean dunkedIn = false;
        int timesBallThrown = 0;

        while (!dunkedIn && timesBallThrown < 3 ) {
            timesBallThrown++;
            dunkedIn = random.nextBoolean();
            System.out.println("Time ball is thrown: " + timesBallThrown + " times. " + "Is it dunked in? " + dunkedIn );
        }

        if(dunkedIn){
            System.out.println("Celebrate Craig falling in Water");
        } else {
            System.out.println("Be sad");
        }


//For Loop method:

        Random random = new Random();
        boolean dunkedIn = false;

        for(int timesBallThrown = 1; !dunkedIn && timesBallThrown <= 3; timesBallThrown++) {
            dunkedIn = random.nextBoolean();
            System.out.println("Times thrown: " + timesBallThrown + " times." + "| Is Craig dunked in? " + dunkedIn);
            }
            if(dunkedIn){
                System.out.println("Celebrate Craig falling in Water");
            } else {
                System.out.println("Be sad");
            }



Nested loops: Mix IceCream sour and sweet

String[] sweetFlavors = {"Caramel", "Cinnamon", "Watermelon", "Baked Beans"};
        String[] savoryFlavors = {"Sea Salt", "Potato Chip", "Carrot", "Barbeque Sauce"};

        for(String sweet: sweetFlavors) {
            for (String savory: savoryFlavors){
                System.out.println(sweet + ", AND " + savory);
            }
        }

//Results:
Caramel AND Sea Salt
Caramel AND Potato Chip
Caramel AND Carrot
Caramel AND Barbeque Sauce
Cinnamon AND Sea Salt
Cinnamon AND Potato Chip
Cinnamon AND Carrot
Cinnamon AND Barbeque Sauce
Watermelon AND Sea Salt
Watermelon AND Potato Chip
Watermelon AND Carrot
Watermelon AND Barbeque Sauce
Baked Beans AND Sea Salt
Baked Beans AND Potato Chip
Baked Beans AND Carrot
Baked Beans AND Barbeque Sauce







// Branching statements
// break - exits the iteration
// continue - stops executing the current iteration and jumps back to the top to start over again
// return - if you are inside of the loop, it will immediately exit the method.