ITEC 120 2012fall dbraffitt ibarland

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lect12a
arrays, cont.

arrays

The before files:

• ArrayDemos.java, the actual code;
• TestArrayDemos.java, all the tests tucked into their own class, so as not to distract from the actual code.
  

  Note that this separation helps javadoc generate documentation for the main functions that is uncluttered with test functions, and it helps reinforce that the test-methods are things without thinking about how the actual code is implemented (“black-box testing”).

• TestUtils.java, general-purpose helper functions TestUtils#equalDoubles(double,double) etc., which don't change from week to week.
  We can simply use¹ this file, unmodified, in each week's project.

• Recall the rainfallExample; first let's factor out the three things it's doing into their own stand-alone functions.
• Write max( double[] ).
  (What's its signature? How to intialize our so-far value?)
• Write indexOfMax.
• Optional/practice: write maxConsecutivePair -- find the max value of two-consecutive days of rainfall.
• How to write min( String[] )?
  What helper function would we like? Could we write that ourselves?
  Let's inspect java.lang.String.
• recall/re-write: countOccurrences(String,char)
• Write countOccurrences(String[], char) Note: this is a nested loop, effectively!
• For practice: write arrayToString( double[] )
• Write a histogram program for letter-frequency (say, lower-case only).
• Discuss the above. Compare to the book's Listing 7.3.

The after files: ArrayDemos.java, along with TestArrayDemos.java, and the general-purpose TestUtils.java.

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©2012, Ian Barland, Radford University Last modified 2012.Nov.12 (Mon)

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