Assignment
Create, using NetBeans, a complete Java program called CalcWeightedAvgDropLowest according to the following guidelines.
For this program, instead of getting the data from the user via System.in, get only input and output file names from the user. (See Horstmann, pp. 319, 320).
The input file - which you need to create and prompt the user for - should be called 'data.txt',and it should be created according to the highlighted instructions below. The input file should contain (in order): the weight, the number, n, of lowest numbers to drop, and the numbers to be averaged after dropping the lowest n values. See the example below. Also, include a method called printResults that prompts the user for the name of an output file and then prints the results to that user-designated output file.
Your main program should contain just three lines like these:
ArrayList inputValues = getData();
double weightedAvg = calcWeightedAvg(inputValues);
printResults(inputValues, weightedAvg);
The inputValues come from a single line in your "data.txt" file such as the following:
0.5 3 10 70 90 80 20
The output file should contain something like the following:
"The weighted average of the numbers is 42.5, when using the data 10.0, 70.0, 90.0, 80.0, 20.0, where 0.5 is the weight used, and the average is computed after dropping the lowest 3 values."
Creating the Input file
To create the input file, while in NetBeans with your project open, click to highlight the name of the project in the Projects tab at the upper left part of the IDE. That tab should be called CalcWeightedAvgDropLowest. Then:
File-→New File...
Keep the Project name at the top; keep Filter blank
Categories → Other (at the bottom of the categories list)
File Types → Empty File (at the bottom of the files list)
Next>
FileName: data.txt
Folder: this should be blank; if it's not, delete whatever's there
Finish
In the empty file data.txt that you just created, add a single line of data like the example above, where the weight is a double (greater than 0.0 and less than or equal to 1.0) and the other numbers are the number, n, of lowest values to drop and then the numbers to be averaged after dropping the lowest n values. Also, instead of displaying the output to the console, let the user choose a file name (as in Horstmann's example), and write the output to a file with that user-supplied name (e.g., output.txt).
Thoughts
It's important that your input file is where NetBeans will look to find it. The above instructions should make sure that that happens.
Make sure you prompt the user for the name of the input file. You can use a prompt like: "Enter "data.txt" (no quotes) for the name of the input file: "
Note that if you run this program from the command line, the input file should be in the same directory as your .class file.