Summary

Lets wrap up what we've learn so far. We have learn how to print, ask users for inputs, using if-else/else-if, loops
and dealing math expressions. Now lets refresh our memory for a little.

The if statement has this form

if ( boolean - expression )
statement...

The if-else statement has this form

if ( boolean-expression)
statement

else
statement

The basic format of a for loop

for ( initialization-expression; testing-expression; counting-expression;)
{

statements;

}

The basic format of a do-while loop

do
{
statement;
}while(expression);

The basic format of a while loop

while (expression)
statement;

Now lets look at a comprehensive example.

/* This is a simple atm program that asks the user to enter a pin number, the pin number is set to 111 then it will verifies if the pin matches if it does match, then the user get to choose, check account balance, deposite, withdraw, or exit. The balance is set to 2000 Overall the program demonstrate the use of loops, if-statements, getting user inputs and making decisions using the inputs * */ import java.util.Scanner; public class Atm { public static void main(String[] args) { int n = 0; int totalamount = 2000; int pinnum; int depot, withdraw; String choices; Scanner key = new Scanner(System.in); // Here we ask the user for the pin number System.out.print("Please enter your pin number: "); pinnum = key.nextInt(); /* If the user's input does not match, we will loop And ask the user to enter the pin again Maximum time we will loop is 3 times, If it loops more than 3 times the program will exit * */ while((pinnum!=111) && (n < 3)) { System.out.print("Please enter your pin number: "); pinnum = key.nextInt(); n++; if(n==3) { System.out.println("Sorry too many tries, program will exit"); System.exit(0); } } /* Here we will use a do-while loop The loop keeps on looping unless the user Enters e to exit * */ do { System.out.println("Enter what would you like to do\n"); System.out.println("D--Deposite, W--Withdraw, C--Check Balance, E--Exit"); System.out.print("Enter your selection now: "); /* Here we use .next() instead of.nexyLine(), because we're only retrieving a single charater * */ choices = key.next(); // Inside this if statement we calculates balance after withdrawing if(choices.equals("W") || choices.equals("w")) { System.out.println("You have selected with draw\n"); System.out.print("Please enter the amount you want to with draw: \n"); withdraw = key.nextInt(); totalamount -= withdraw; } // Inside this else-if statement we checks the user's balance else if(choices.equals("C") || choices.equals("c")) { System.out.println("You have selected check balance\n"); System.out.print("Your account balance is " + totalamount + "\n" ); } // Inside this else-if statement we calculates the balance after deposite else if(choices.equals("d") || choices.equals("D")) { System.out.println("You have selected deposite\n"); System.out.print("Please enter the amount you want to deposite: "); depot = key.nextInt(); totalamount += depot; } // Inside this else-if statement we only have one statement, which will exit the program else if(choices.equals("E") || choices.equals("e")) { System.exit(0); } }while(true); } }

ClickHere to download Atm.java