Reading data in applications
THIS IS NOT PART OF THE AP SUBSET
Reading data into application can be accomplished by a variety
of means. The book uses something called scanner classes, which
is not to difficult. Again, you dont need to fully understand the
class. We just need to be able to use it (this is called abstraction).
You will need to import the proper class. To import means to include
other Classes so that we can use them. Some classes like the Math
class we dont need to import because it is so common that is it
imported (included automatically). But we will need to import the
Scanner class. Which is located in the java.util package. (A package
is a set of classes bundled together).
to use the Scanner, we import:
Now in our code we first have to create an instance of the Scanner.
It probably makes sense to make it global(put it at the beginning
of your class).
Scanner scan=new Scanner(System.in);
Now anywhere in your code where you want to read, you do one of
- String theReadString=scan.nextLine(); // This
would read the next line as a String
- int theReadInt=scan.nextInt(); // This would
read the next line as an int
- double theReadDouble=scan.nextDouble(); // This
would read the next line as a double
An example is included below:
* This simple class is to test the Scanner class' ability to read user input.
public class TextReader
Scanner scan=new Scanner(System.in); //The Scanner constructor requires the use of the io class
public void testOfScannerClass()
//test of reading Strings
System.out.println("Type in a string");
System.out.println("In case you forgot, you just typed " + theString);
//test of reading int
System.out.println("Type in a number");
System.out.println("In case you forgot, you just typed " + theInt);
//test of reading double
System.out.println("Type in a decimal");
System.out.println("In case you forgot, you just typed " + theDouble);
//main method for Eclipse
public static void main(String args)
TextReader t=new TextReader();