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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 Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own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))
Length, size or capacity in Java?

You get the length of an array, but you ask about the size() of an ArrayList, and you can inquire into the capacity() of a StringBuffer. Aren't they really all the same sort of thing? Which does Java use in which circumstance?

Java uses the word length when you're asking about something that can be determined by telling you the distance from the start to the end of something - thus an array, with fixed size elements arranged sequentially in memory, is going to be a length.

Java uses size where you're looking at a measure of the number of elements in something which is not in successive memory locations, or may not be, or where the elements themselves differ in size so you can't find out how many of them there are by measuring the distance from start to end.

And Java uses capacity where you're being told how much something can hold, and not how much it's holding at the moment.

Do you add brackets after the length / capacity / size word? If you're looking at a variable within the object, you don't, but if you're calling a method you do. Which is it in which circumstances? I have no magic answer - you just need to learn / know.




myarray.length - array length - [example]

MyArrayList.size() - number of elements in an Array List - [example]

MyString.length() - String length - [example]

MyStringBuffer.length() - String Buffer length - [example]

MyFile.length() - Number of bytes in a file - [example]

MyVector.size() - Number of elements in a Vector [example] and [example in Servlet]

MyAppletDimension.size() - returns an object with the width and height of an applet. This is deprecated and you should now use getsize ...

MyAppletDimension.getsize() - returns an object with the width and height of an applet - [example]

MyStringBuffer.capacity() - the number of characters that a StringBuffer can currently hold

(written 2010-02-24, updated 2010-03-03)

 
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles
J802 - Java - Abstract Windowing Toolkit
  [1325] Java - Client side applet applications as well as server side - (2007-08-29)
  [2245] Client side (Applet) and Server side (Servlet) Graphics in Java - (2009-06-17)
  [2654] Java - from applets to servlets. JSPs and more - (2010-02-27)
  [3049] Computer Graphics is fun - even if Java Applets are Old Hat - (2010-11-13)

J714 - Java - Fundamental classes
  [42] Do languages change? - (2004-09-08)
  [1062] Java sorting - comparable v comparator - (2007-02-02)
  [1502] Java, sorting, ArrayList example, generics - (2008-01-11)
  [1910] Java - Generics - (2008-11-27)
  [2323] Java Collection Objects in the java.util package - (2009-08-05)
  [2418] Viv.java uses unchecked or unsafe operations - explanation and cure - (2009-09-24)
  [2421] Sorting Collections of Objects in Java - (2009-09-25)
  [2734] for and foreach in Java - (2010-04-22)
  [2920] Sorting - naturally, or into a different order - (2010-08-14)
  [3048] String handling - from first steps to practical examples - (2010-11-13)
  [4330] Java - factory method, encapsulation, hashmap example - (2014-11-27)
  [4396] Java Utility class - flexible replacement for array. Also cacheing in objects and multiple catch clauses example. - (2015-01-16)
  [4421] How healthy are the stars of stage and screen? - (2015-02-09)
  [4431] A Java servlet that is also a stand alone program. And a server that is also a web client. - (2015-02-19)

J707 - Java - Strings
  [1446] An answer to a student asking 'Help' - (2007-11-27)
  [1557] Trying out our Java examples on our web site - (2008-02-27)
  [4393] Splitting Java strings and extracting numbers - (2015-01-13)
  [4414] Java - converting an integer to a fixed length string - (2015-02-04)


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Java Server Pages - putting it all together
Reading and writing cookies in Java Servlets and JSPs
Calculation within objects - early, last minute, or cached?
Getting a phone line changed ...
Length, size or capacity in Java?
Java arrays - are they true arrays or not?
Removing duplicates from a MySQL table
Compile but do not run PHP - syntax check only
Optimising and caching your MySQL enquiries
Counting rows in joined MySQL tables
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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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