Long, Longer, Longest in Java

For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))

If you want to find out how long a Film3 is, in the class that I use on our private Java Programming courses, you can call the getminutes method. That's standard OO stuff. But what if you want to find out which is the longer of two Film3s or the longest of a whole array of them?

Don't re-write code!!!. So your longer method should call getminutes, and your longest method should call either longer or getminutes directly. Here's an example:

public int getminutes() {

   return minutes;

   }

public Film3 longer(Film3 that) {

   int m1 = this.getminutes();

   int m2 = that.getminutes();

   if (m1 < m2) return that;

   return this;

   }

public static Film3 longest(Film3 [] ofthese) {

   Film3 sofar = ofthese[0];

   for (int owabout=1; owabout<ofthese.length; owabout++) {

   sofar = sofar.longer(ofthese[owabout]);

   }

   return sofar;

   }

longer is a method that runs on one object, with another passed in as a parameter:
current = Library[1].longer(Library[2]);

By contrast, longest is a class or static method that runs on a whole array of objects:
current = Film3.longest(Library);

You might wonder if longest could simply have run on the class as a whole and returned the largest defined Film3, but that would not be a good solution as you're likely to want to find (say) the longest horror film or the longest one for children, which will all be defined at the same time.

Links - Sample Program and the class that goes with it
(written 2008-11-25, updated 2008-11-24)

Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles

J706 - Java - Objects and Classes
  [96] Variable Scope - (2004-10-22)
  [477] Class, static and unbound variables - (2005-10-25)
  [1163] A better alternative to cutting and pasting code - (2007-04-26)
  [1296] An example of Java Inheritance from scratch - (2007-08-08)
  [1500] First Class Java. First step and moving forward. - (2008-01-10)
  [1925] Introduction to Object Oriented Programming - (2008-12-06)
  [2169] When should I use OO techniques? - (2009-05-11)
  [2422] Looking inside Java classes - javap and javadoc - (2009-09-25)
  [2616] Defining a static method - Java, Python and Ruby - (2010-02-01)
  [2651] Calculation within objects - early, last minute, or cached? - (2010-02-26)
  [4413] Binomial Coefficient (Pascal Triangle) objects in Java - (2015-02-03)
  [4422] Objects - from physical to virtual or abstract - Java - (2015-02-10)

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Java - Generics
javax.servlet cannot be resolved - how to solve
Java CLASSPATH explained
Melksham Hotel Rates
Long, Longer, Longest in Java
A Gold Star for First Great Western Customer Service
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daemons - what is running on my Linux server?
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This is a page archived from The Horse's Mouth at http://www.wellho.net/horse/ - the diary and writings of Graham Ellis. Every attempt was made to provide current information at the time the page was written, but things do move forward in our business - new software releases, price changes, new techniques. Please check back via our main site for current courses, prices, versions, etc - any mention of a price in "The Horse's Mouth" cannot be taken as an offer to supply at that price.

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