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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.