Lesson02

Lesson Two

Table of Contents

The Lesson
The Program

The Lesson

• In this lesson you can see how to get input from the user:
  • Scanner:
    • Scanner is a class that we create an object out of in order to obtain input from the console.
      • Scanner is going to be the type for our variable (remember how I said classes can be used as types?).
      • To create a Scanner object you must use "new Scanner(System.in)".
        • Do not worry about creating objects and how this works as we'll be dealing with that subject soon enough.
    • Once you've created your object you must store it within a variable (we use input in this example).
    • In order to obtain any information from the scanner there are three important methods you must remember:
      • next() - This method will input up until the first whitespace in the console and return it to you in a String.
        • If "abcdefg" is in the console then next() will first return "a", then "b", etc...
      • nextLine() - This method will return all input typed so far up and until the user hit the RETURN/ENTER key.
        • If "abcdefg" is in the console then nextLine() will return "abcdefg".
      • nextInt() - This method will return what was in the console as if it was an int.
        • If "12" is in the console then nextInt() will return 12.
        • If "abc" is in the console then nextInt() will cause an error as "abc" is not an int.
        • You can mess around with typing in different things into the console and seeing what nextInt returns.
      • Keep in mind none of these methods will return anything until the enter key is pressed.
        • This means you need to pay attention to what you are doing or else you could easily do something wrong.
      • Also keep in mind that there are a lot more methods that you can call that you may use in the future.
    • Once you are done working with a scanner be sure to call the close() method on it so that it is not taking up system resources.
      • This is something we will discuss in more detail much much later but you should learn to form good habits.

The Program

• In this program we do something very similar to what was done in the last lesson's program.
• The only difference is that we ask the user for their name, age, and favoriteLetters and then use that.