Create a directory for this exercise and download MeanValue.java into it. This file contains the skeleton of a small program to compute the arithmetic mean of a set of numerical values, supplied via the command line. Your task is to add the missing code to this skeleton.
In the static method meanValue()
, write code that will compute the mean of
the double
values supplied via the array parameter data
. You can assume
that the array always contains at least one value. The result of computation
should be returned by the method.
In main()
, write code that uses the meanValue()
method to compute the
mean of values supplied on the command line. Note that args
, which holds
the command line arguments, is an array of strings. You will therefore
need to create another array, holding the equivalent double
values.
The mean of the supplied values should be displayed to three decimal places
of accuracy, using System.out.printf()
. If no values have been supplied,
the program should display a usage message via System.err
and then
terminate with a non-zero exit status.
Here are examples of expected program behaviour:
$ java MeanValue 1.2 0.7 4.3
Mean value = 2.067
$ java MeanValue
Usage: java MeanValue <values...>
Consult the Java Tutorials if you need help with processing data from the command line.
You can use static method Double.parseDouble()
to convert a string into
a double
value. See the Double API documentation for further
details.
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