Even Better IO

1
Even Better IO

• Getting stuff other than Strings

2
Problem

• Most programs work with data other than strings.
• So far all we have seen is how to read strings
• What do we do?

3
Java has an answer

• Of course, Java has an answer
• Java supplies methods for converting strings to
  each of the built-in types.
• For example to get a double value out of a string
  d, use
• myDouble Double.parseDouble( d )
• This of course will throw an exception if the
  value in d is not a double

4
Other methods

• All of the object types that mirror the built-in
  types have methods that are similar to
  parseDouble
• For example, the Integer has parseInteger()
• These methods require that you know what type of
  value is stored within the string
• Which you will have a lot of the time

5
But wait, how can we use these methods

• You may be asking yourself, how can we use these
  methods without an object around.
• If you noticed in both of those last examples,
  the object name started with a capital letter
• That is not the usual style
• Hmmwhat does that mean.

6
Static methods

• These methods that we are using are called static
  methods
• That means we dont need an object of that class
  to use the method.
• A static method is shared among all instances of
  that class, just like static members.
• Static methods can only operate on parameters and
  static members.

7
What does this mean for me?

• Now, we can actually process a file and do stuff
  with whats inside, other than count.
• We can expect to open a file, read the
  information out, and compute some result based on
  what was inside.
• This will require either knowing what is inside,
  or a lot of trial and error in the code.
• We will work with the former