Reading from a Datafile

To prepare for your directed program during Tuesday's Short Lab, please create an application called ReadIn and add this class to your project: InputDataFile.java. Then download and save these 2 files: names.txt names1.txt

After completing the program, read the rest of these notes and see if you can better follow what the code is doing.

• Remember that for command-line arguments, the the data is automatically set up by the JVM to be in the array called args.

• We have also populated an array using separate assignment statements and array initialization (shown in Enhanced for Loops).

• You can also prompt the user for data and create the objects to store in the array (your part to write in the main() of ConnectTheDots) from your homework).

• This is typical for small amounts of data that is organized in an array simply to make processing more efficient. If we have a large or an indeterminant amout of data, these techniques will not work.

• An array is also often used to read in data from from a datafile, or other advanced schemes like reading the data from a database.

• You will write a program that will read string data from a datafile and storing the data in an array for later processing.

  1. Read in a value.

  2. If we have room in the array, store it in the next available slot.

  3. If we do not have room, print a warning message indicating that not all values were read in.

  4. Continue reading until all the values have been read from the datafile or until the array is full.

• Note: Our algorithm would be the same if we read user input and stored it in an array for processing. The only difference is be where the data is read from - in this case, from a datafile instead of the keyboard.

• Note: we are reading data, so our code will follow the basic structure for a while loop that gets input:

  The Standard Structure of a While Loop that Gets Input

  Get Input
  While (input ok)
  {
  	Process
  	Get Input
  }
  

• Since we are reading from a datafile, the check for input being ok will be to check if the input is null. Our processing step will be to add the data that was just read in into our array. After we have read in the array, we will print it out.