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This essay developed out of conversations I've had with several other programmers about why Java smelled suspicious. It's not a critique of Java!
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" Java provides the industry - software companies and customer alike , an opportunity to create a true open computing environment where software is portable,
and customers benefit from increase competition. "
Java and the Future
December 1, 2008-LEJB 3.1: EJB New and Improved!
The EJB 3.0 specification was a huge improvement from what you were used to in the early versions of EJB. Available as an early draft, EJB 3.1 has many more features and is even easier to use.
December 1, 2008-Should Java Assert that Network I/O Can't Occur on the UI Thread?
Doing network I/O on the user interface (UI) thread is bad. Most developers know that and can tell you why; unfortunately, it's still done.
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JSP Interview Questions
How can I implement a thread-safe JSP page? What are the advantages and Disadvantages of using it?
You can make your JSPs thread-safe by having them implement the SingleThreadModel interface. This is done by adding the directive <%@ page isThreadSafe="false" %> within your JSP page. With this, instead of a single instance of the servlet generated for your JSP page loaded in memory, you will have N instances of the servlet loaded and initialized, with the service method of each instance effectively synchronized. You can typically control the number of instances (N) that are instantiated for all servlets implementing SingleThreadModel through the admin screen for your JSP engine. More importantly, avoid using the tag for variables. If you do use this tag, then you should set isThreadSafe to true, as mentioned above. Otherwise, all requests to that page will access those variables, causing a nasty race condition. SingleThreadModel is not recommended for normal use. There are many pitfalls, including the example above of not being able to use <%! %>. You should try really hard to make them thread-safe the old fashioned way: by making them thread-safe .
Using jspInit and jspDestroy(Example code)
<HTML>
<HEAD>
<TITLE>Using jspInit and jspDestroy</TITLE>
</HEAD>
<BODY>
<H1>Using jspInit and jspDestroy</H1>
<%!
int number;
public void jspInit()
{
number = 5;
}
public void jspDestroy()
{
number = 0;
}
%>
<%
out.println("The number is " + number + "<BR>");
%>
</BODY>
</HTML>
What is the difference b/w variable declared inside a declaration part and variable declared in scriplet part?
Variable declared inside declaration part is treated as a global variable.that means after convertion jsp file into servlet that variable will be in outside of service method or it will be declared as instance variable. And the scope is available to complete jsp and to complete in the converted servlet class. where as if u declare a variable inside a scriplet that variable will be declared inside a service method and the scope is with in the service method.
What is a Expression?
An expression tag contains a scripting language expression that is evaluated, converted to a String, and inserted where the expression appears in the JSP file. Because the value of an expression is converted to a String, you can use an expression within text in a JSP file. Like
<%= someexpression %>
<%= (new java.util.Date()).toLocaleString() %>
You cannot use a semicolon to end an expression
What is a Declaration?
A declaration declares one or more variables or methods for use later in the JSP source file.
A declaration must contain at least one complete declarative statement. You can declare any number of variables or methods within one declaration tag, as long as they are separated by semicolons. The declaration must be valid in the scripting language used in the JSP file.
<%! somedeclarations %>
<%! int i = 0; %>
<%! int a, b, c; %>
