Shoaib Ali It's bloggin time

Another fascinating tool I stumbled upon. Never thought I would ever need anything like this but this was very useful for a secret project I am working on.

This memory analyzer gives you a good overview of your memory utilization based on segments. Which objects are using how much memory and whats garbage collector up to.

It reads in dump files - on OSX they suggest using jmap.

So far it will tell you :-

What are the sizes of the collections, which my objects are keeping?

What is the fill ratio of the collections held by my objects?

Are the hash functions of my objects really working fine?

An easy way to look at the content of HashMaps
Arrays!
* "Arrays Grouped By Size" - works on both primitive and Object arrays
* "Array Fill Ratio" - does not work on primitive arrays. Provides the ratio between non-null elements in the arrays and the length of the arrays

I used something Ruby | Rails taught me in m java jdbc assignment. It's not related to rails in any way then SQL in general. It's the concept of using Prepared statements.Really useful in this particular scenario.

public String showLoanedBooks() {
public String showLoanedBooks() {
PreparedStatement sa = null;
PreparedStatement sb = null;

String result = "";
boolean r = false;
String selectbooksql = "SELECT DISTINCT ISBN, Title, Edition_No, NumofCop, NumLeft FROM Book NATURAL JOIN Cust_Book;";
String selectauthorsql = "SELECT Surname FROM Author NATURAL JOIN Book_Author WHERE ISBN = ? ORDER BY ISBN;";
String selectcustomersql = "Select CustomerID, L_Name, F_Name, City from Customer natural join Cust_Book WHERE ISBN = ? ;";
try{
result = "Show Loaned Books: \n\n";

Statement s = con.createStatement();
sa = con.prepareStatement(selectauthorsql);
sb = con.prepareStatement(selectcustomersql);

ResultSet rs = s.executeQuery(selectbooksql);

while (rs.next()){
r = true;
//Going through each book Book

Things to watch out for when configuring sendmail. Specially when deploying it for relaying mail for php via your ISP.

Although I thought sendmail was a out-of-box solution for this but I've ran in to this trap so many times that I thought I might as well document it for future, instead of googling everytime.

On debian based distro anyway you just go ahead install sendmail as such.


sudo apt-get install sendmail


Once installed make sure your hostname is correctly configured for that machine. Anything like localhost.localdomain will make sendmail shat itself.

You can always check the log for sendmail to see whats going on.


sudo tail -f /var/log/mail.log

So, open up hostname and hosts file in /etc/

Inside the hosts file make sure it looks something like this

127.0.0.1 localhost
192.168.3.1 yourwebsite.co.nz webserver

Also make sure webserver is the name also mentioned in your hostname file.

Once done that you can restart this service for it to take effect and restart sendmail too.

Finally a "real" gaming console! This is the sort of stuff that big companies try and stop develop otherwise they run out of ways to make money! This is not pandora
is all about. Have a look at its features

• ARM® Cortex™-A8 600Mhz+ CPU running Linux
• 430-MHz TMS320C64x+™ DSP Core
• PowerVR SGX OpenGL 2.0 ES compliant 3D hardware
• 800x480 4.3" 16.7 million colours touchscreen LCD
• Wifi 802.11b/g, Bluetooth & High Speed USB 2.0 Host
• Dual SDHC card slots & SVideo TV
• Dual Analogue and Digital gaming controls
• 43 button QWERTY and numeric keypad
• Around 10+ Hours battery life

ARM cpu - the most compatible linux cpu ever made. ARM CPU's are specially developed to run with linux.

Dual SDHC card slots means you can emulate more then one game from different consoles at the same time, which is really cool.