Java KeyWord Explanation

Hi there!
I have to prepare a report, where I present a simple Codeexample of an JavaBean-Implementation. My problem is, that I am not very familar to Java.
Now I need a source, where to consult the meaning of the basic keywords.
i.e., if I have a code-line like
public class MyClass extends SimpleBeanInfo
I need a short explanation for the Keywords and what they are for (public, class, extends).
I hope, you know such a library.
Thanks in advance,
Frank

You'll find the above mentioned langspec from here: http://java.sun.com/docs/books/jls/second_edition/html/jTOC.doc.html
Chapter 8 seems to have stuff related to the class declaration. But the meaning of them is given quite implicitely... so let's look it up in google: http://www.google.com/search?q=java+keywords
the third hit looks promising, doesn't it?

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Which java keyword cannot be used inside the body of a static method?

Which java keyword cannot be used inside the body of a static method, but may be used without problems in a non-static method?

But javac doesn't complain. So I was not partially wrong -- I was completely wrong.It's still better not to use the "this", though. When you explictly reference a static member via an instance reference (theFoo.bar or this.bar, as opposed to Foo.bar) the JLS requires a check that the reference is non-null. Clearly "this" is always non-null, but javac still puts in half of the check. Take the simple class public class Test {
    static int field;
    public void setField(int i) {this.field=i;}
    public void staticSetField(int i) {field=i;}
} and observe the bytecodes produced: $ javap -c Test
Compiled from "Test.java"
public class Test extends java.lang.Object{
static int field;
public Test();
Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   return
public void setField(int);
Code:
   0:   aload_0
   1:   pop
   2:   iload_1
   3:   putstatic       #2; //Field field:I
   6:   return
public void staticSetField(int);
Code:
   0:   iload_1
   1:   putstatic       #2; //Field field:I
   4:   return
}The JIT will get rid of it, but you may as well avoid the waste in the first place. (And if you really do want to check that the reference is non-null, do the check explicitly so that maintainers know it's intentional).

Can we give a class name by java keyword ?

can we give a class name by java keyword ?e. can we create a class call "for" / "if" anyhow ? Is there some way to create such kind of classes .. Is is possible with some other java like language.. & if there is any language & how one can embed the script/language in java ..
Please let me know
Regards

can we give a class name by java keyword ?e. can we
create a class call "for" / "if" anyhow ? Is there
some way to create such kind of classes .. Is is
possible with some other java like language.. & if
there is any language & how one can embed the
script/language in java ..
I give up - why would you want to?

Java error explanation

Any idea which direction I should head to learn more about this error?
# HotSpot Virtual Machine Error, Internal Error
# Please report this error at
# http://java.sun.com/cgi-bin/bugreport.cgi
# Java VM: Java HotSpot(TM) Server VM (1.4.1_07-b02 mixed mode)
# Error ID: 434F4E43555252454E542D41524B335745455027454E45524154494F4E0E4350500B97 FF
# Problematic Thread: prio=1 tid=0x2d340 nid=0x1 runnable
Abort - core dumped
in this environment.

The instructions for what to do are in the error message. Is that the entire text of the message?

Java Code explanation

Iam new in java and on going learning, iam puzzle with this code, based on this code why the value x1 change when value x2 is set to different time? please do explain to me.. TQ
class MyTime {
     public static void main(String[] args) {
          Time x1, x2;
          x1 = new Time();
          x1.setTime(1, 00);
          x2=x1;
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          x1.whatTime();
          System.out.println();
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          System.out.println();
          x2.setTime(3, 00);
          System.out.print("x1: ");
          x1.whatTime();
          System.out.println();
          System.out.print("x2: ");
          x2.whatTime();
          System.out.println();
}

What you have to realiuse is that x1 and x2 are not Time objects. They are just pointers that point to the same Time object. So for example say you have two people called x1 and x2 standing and pointing at stuff written on a blackboard, the same blackboard. So if you get person x1 to make any changes to what is written on the blackboard, person x2 is still pointing to the same stuff on that same blackboard.

Question about the java doc of String.intern() method

hi all, my native language is not english, and i have a problem when reading the java doc of String.intern() method. the following text is extract from the documentation:
When the intern method is invoked, if the pool already contains a string equal to this String object as determined by the equals(Object) method, then the string from the pool is returned. Otherwise, this String object is added to the pool and a reference to this String object is returned.
i just don't know the "a reference to this String object is returned" part, does the "the reference to this String" means the string that the java keyword "this" represents or the string newly add to the string pool?
eg,
String s=new String("abc"); //create a string
s.intern(); //add s to the string pool, and return what? s itself or the string just added to string pool?greate thanks!

Except for primitives (byte, char, short, int, long, float, double, boolean), every value that you store in a variable, pass as a method parameter, return from a method, etc., is always a reference, never an object.
String s = "abc"; // s hold a reference to a String object containing chars "abc"
foo(s); // we copy the reference in variable s and pass it to the foo() method.
String foo(String s) {
return s + "zzz"; // create a new String and return a reference that points to it.
s.intern(); //add s to the string pool, and return what? s itself or the string just added to string pool?intern returns a reference to the String object that's held in the pool. It's not clear whether the String object is copied, or if it's just a reference to the original String object. It's also not relevant.

'Finally' is a rip off !! No use in java !!

Hello guyz,
Just wanted to discuss about the use of the keyword finally.
"The finally is a Java keyword that is used to define a block that is always executed in a try−catch−finally statement. In java, there are three clauses named try, catch and finally used as exception handler components. A finally block
typically contains cleanup code that recovers from partial execution of a try block."
I mean if i don't even write my code in finally still it will execute outside the block if an exception occurs.
how ever if an exception does't occur i have the same code executing twice....
public class one
     public static void main(String args[])
          int i=27;
          try
               System.out.println(i/2);
               System.out.println("hey");
          catch(Exception e)
               System.out.println(e);
          finally
               System.out.println("hey");
}please clarify... or i am going bananas here...

like in this code
public class one
     public static void main(String args[])
          int i=27;
          try
               System.out.println(i/0);
               System.out.println("hey");
          catch(Exception e)
               System.out.println(e);
          System.out.println("hey");
}

JAVA Feature

As all we know, that java create its own platform which over its underlaying h/w , s/w . That's why java offers the nature of plateform indpendency. Due to which unlike any other language like c or c++ datatype and its storage size never depends upon underlaying syatem arch. My question is this since java creates such a protection for plateform independecy then what is the use of keyword "strictfp" which takes special care of floating point calculation ?

strictfp is a Java keyword used to restrict floating-point calculations to ensure portability. The modifier was introduced into the Java programming language with the Java virtual machine version 1.2.
In older JVMs, floating-point calculations were always strict floating-point, meaning all values used during floating-point calculations are made in the IEEE-standard float or double sizes. This could sometimes result in a numeric overflow or underflow in the middle of a calculation, even if the end result would be a valid number. Since version 1.2 of the JVM, floating-point calculations do not require that all numbers used in computations are themselves limited to the standard float or double precision.
However, for some applications, a programmer might require every platform to have precisely the same floating-point behavior, even if some platforms could handle more precision. In that case, the programmer can use the modifier strictfp to ensure that calculations are performed as in the earlier versions?only with floats and doubles.
The modifier can be used in combination with classes, interfaces and methods.
this was taken from wikpedia hopefully that explains it to you. (i don't know if you are using a translator or not, but please proof read your posts, it took me awhile to figure what you meant.)
(java creates it's own platform? Think about it, java provides portabilty how? (think peers))
cheers
octaclot
Edited by: Octaclot on Oct 25, 2007 4:15 AM

End of year Java Project Question - File I/O

Hello.
My project involves allowing the user (which should be someone learning the very basics of Java and OOP) to copy and paste a one class program into a JTextArea. Then, they click a button which analyzes their code and visually shows how objects in their program interact with one another. My problem is that I am not sure of how to GET their code after it is pasted. I read up on FileReader/Writer but it seems like they save .txt files; I do not need to save the user's program on disk but only in memory and analyze their. Does anyone know of how I could do this? I obviously do not want to save it as a String because if the code is 100 lines long, then it just gets too messy. I would like to be able to read line by line what the user is trying to accomplish in their program in a txt file. If I could save a txt file and at close of the program, delete it, that could work too.
Any help? Thanks in advance.

Does anyone know of how I could do this? I obviously do not want to
save it as a String because if the code is 100 lines long, then it just
gets too messy. I would like to be able to read line by line what the
user is trying to accomplish in their program in a txt file. If I could save
a txt file and at close of the program, delete it, that could work too.huh? you can write a whole application on one line
for (int i = 0 ; i < 10; i++){ System.out.println("Line 1"); System.out.println("line 2"); etc... }
This is ambitious for an end of class project (a class project even)
your application have to check the syntax, java keyword, keep what object is instantiate, what method is invoked..if that method belongs to the class...etc..

Syntax (keywords) highlighting ?

Hi all,
I am writing a JAVA code editor.
How can I highlight JAVA keyword according to JAVA syntax library. Such as this, static, System.out.println
Thank you

You need to do a search first. This has been discussed a great deal on this forum - in the upper right, type "syntax highlighting" and search. You will get back numerous links to threads in which this very topic has been discussed. Read those threads and figure out what you want to do. Try to code some examples and post again when you have specific questions about your application.
Good luck!

Is there any difference between java Beans and general class library?

Hello,
I know a Java Bean is just a java object. But also a general class instance is also a java object. So can you tell me difference between a java bean and a general class instance? Or are the two just the same?
I assume a certain class is ("abc.class")
Second question is is it correct that we must only use the tag <jsp:useBean id="obj" class="abc.class" scope="page" /> when we are writng jsp program which engage in using a class?Any other way to use a class( create object)? such as use the java keyword "new" inside jsp program?
JohnWen604
19-July-2005

a bean is a Java class, but a Java class does not have to be a bean. In other words a bean in a specific Java class and has rules that have to be followed before you have a bean--like a no argument constructor. There are many other features of beans that you may implement if you so choose, but read over the bean tutorial and you'll see, there is a lot to a bean that is just not there for many of the Java classes.
Second question: I'll defer to someone else, I do way to little JSP's to be able to say "must only[\b]".

Please uggest some java Interfaces

I write all my java programmes in notepad.
is there some interface or downloadable program where I can type java and it will have some color, etc?
notepad is a pain especially when my programmes get longer and longer
thanks

If you like to type in a plain text editor but want to get highlights on Java keywords try Ultra Edit. I used it for a long time. You can even start programms from within, so you can start your compile and run by using key strokes while editing.
If you like to enhance your programming not only by highlighted Java keywords but want to use a real development tool with debugger, object tree, package management, coding help with a tooltip of all possible methods you can use with a certain object after typing a point and many things more just use eclipse. It's open source, you can get it at www.eclipse.org.
Rommie.

Help with creating a doubly linked list

So I have been working with this file our teacher gave us, which is his own "list" ADT which I posted below (with out the comments so it doesn't stretch the page for ever)
My question is, I cant really creat a DLL from this because I have nothing for the head, no previous or next or any of that...So could some one help me get off to the right start? Some of my class mates were like "create a SLL and then reverse it" well thats all fine and dandy but how?
A couple other student said "With this DLL i only had to write two lines for each method to implement the list"...Can that be done? Theres NO documentation any where on a DLL for java, and the linkedList in the java api...I dont think that's a DLL...
I SERIOUSLY need a nudge in the right direction....
package assignment.four.utilities;
import java.io.Serializable;
public interface List<E> extends Serializable
     public int size ();
     public void clear ();
     public boolean add (int index, E toAdd) throws NullPointerException,
                                                                 IndexOutOfBoundsException;
     public boolean add (E toAdd) throws NullPointerException;
     public boolean addAll (List<? extends E> toAdd) throws NullPointerException;
     public E get (int index) throws IndexOutOfBoundsException;
     public E remove (int index) throws IndexOutOfBoundsException;
     public E remove (E toRemove) throws NullPointerException;
     public E set (int index, E toChange) throws NullPointerException,
                                                            IndexOutOfBoundsException;
     public boolean isEmpty ();
     public boolean contains (E toFind) throws NullPointerException;
     public E [] toArray (E [] toHold) throws NullPointerException;
     public E [] toArray ();
     public Iterator<E> iterator ();
}Again with my statement. Using that List ADT HOW do you even get started in the right direction to creating a DLL? I can use this to create an array list but i dont think i can for a dll?
Edited by: user8974754 on Nov 20, 2010 8:00 PM

user8974754 wrote:
Ok thats fine and dandy but we never learned how to make a DLL we learned last semester how to make a SLL and I kinda get that but again with the So, you know how to make an SLL? Then I would suggest starting with that. For instance, you know how to define a Node or Element or whatever-you-want-to-call-it class that holds Data and Next? Start with that, and see if you can work out how to add a Previous.
"there's nothing on DLL's" except for the same line over and over "They go backwards and forwards" and Im sorry but that doesn't cut it......So, [url http://www.youtube.com/watch?v=Ijae2WHdc9I]you know how to count blocks, but you don't know how to count oranges? That is, you know how to make forward links in a list, but not backward links? Really?
Is there any examples of Java Dlls implementing lists and bla?I'm sure there are plenty, and I'm sure your google works as well as mine.
like we cant implement any thing else as far as I know, it can only be this list....When I said you need to implement the various pieces, I meant in the normal English sense of the word, not in the Java keyword sense. Implementing a Node in the general sense is part of "implements List" in the Java keyword sense.
I know the asking for a sample implementation might be considered cheating in some peoples books Yup.
but i learn best from examples, explanations and what not...There's a world of difference between an example of a different use of the concepts that you're trying to learn and just doing your work for you. Whatever concepts this lesson is teaching that are being tested and reinforced by this homework, you can find plenty of examples without somebody providing a DLL implementation for you.
Edited by: Am I still jverd? on Nov 20, 2010 9:05 PM

Coloured Text

I am trying to develop an editor for 8085 assembly language programming. I need to display all key words like MVI MOV ADD ADDI etc in a colour different than the rest of the text. How do I do it? Any help would b greatly appreciated.

http://www.discoverteenergy.com/files/SyntaxDocument.java
The above class in an attempt to highlight java keywords, which it does pretty well. Most of the code in the class is related to highlighting multi-line comments, which it doesn't do very well. If all you need is keyword highlighting take a look at the keyword highlight code and throw out the rest.

In your experience

I was going to post the link here but then I would be advertising and that is not my idea, so I decided to just post the content of the course.
In your experience would you say that this is a good course for me to start with:? I do not have any back ground in programming but I am king to learn.
In total this is a 5 day course based in London.
Course Content
Module 1 - Getting Started
Origins of the language and its key features
Describing the Java Runtime Environment and the components of the Java 2 Standard Edition (J2SE)
Comparing local and distributed Java applications and associated security features
Writing, compiling and running a simple Java application
Using documentation for the J2SE class libraries
Module 2 - Object-Oriented Programming
Defining classes, objects, variables and methods
Building an object and understanding object references and garbage collection
Using constructor methods to initialise objects
Using package and import statements to access the J2SE class libraries
Applying access modifiers to object members
Module 3 - Keywords and primitive types
Recognizing Java Keywords
Listing the eight primitive types
Understanding conversion and casting of primitive types
Recognizing and using Java operators
Module 4 - Flow Control
Iteration using for loops, while loops and do-while loops
Building nested loops, and breaking out of a loop
Using labels and the continue keyword
Building alternative execution paths with a switch block
Module 5 - Arrays
Declaring, creating and initialising arrays of primitive types
Building arrays of objects
Building multi dimensional arrays
Passing arguments into the main method of a command line application
Building an application that uses arrays, method calls and iterative loops
Module 6 - Object-Oriented design
Describing the three pillars of object-oriented design (Inheritance, Polymorphism and Encapsulation)
Inheritance and building a derived class
Understanding a class hierarchy and the methods of the Object class
Describing polymorphism and building an overriding method
Enforcing polymorphism with interfaces and abstract classes
Encapsulation and its advantages in producing maintainable code
Module 7 - Further Class Features
Building overloaded methods and constructors
Declaring and using static variables and methods
Declaring and using final classes, variables and methods
Module 8 - Exceptions
Defining exceptions and building code to handle a runtime exception
Explaining the Exception class hierarchy and categories of exceptions
Declaring methods that may throw exceptions
Using the throw keyword forward an exception
Building a user-defined Exception class
Module 9 - Collections
Categorising collections classes by the interfaces that they implement
Using Sets, Lists and Maps to store collections of objects at runtime
Building an iterator to access the objects in a Set
Adding key - value pairs to a HashMap
Using object reference casting when assigning references from a collection
Module 10 - Building a Graphical User Interface (GUI)
Describing the Swing package and its components
Building an application window and adding components to the Content Pane
Explaining layout managers and the rules by which they position components on a window
Using BorderLayout, FlowLayout, GridLayout and GridBagLayout managers
Building inner classes to handle events in a GUI , such as a menu selection
Adding a user interface to the command line application built during previous modules
Module 11 - Applets
Comparing GUI applications to applets
Explaining applet methods that are called by the browser
Writing HTML code to display an applet within a web page
Executing a Java 2 applet on any browser by automatically downloading the Java Runtime Environment
Using the paint method to draw an image on a component
Module 12 - Threads
Creating threads to enable concurrent execution of multiple tasks
Declaring synchronized code to prevent simultaneous access to a method by more than one thread
Moving threads between states using the wait and notify methods
Using a shared object to communicate between threads
Module 13 - I/O Streams
Interrogating the local file system
Using Character Streams to read and write to a text file
Understanding processing streams and linking them to sink streams
Building byte streams to send and receive binary data
Using object serialization to give persistence to objects
Module 14 - Networking
Distinguishing between Transmission Control Protocol (TCP) and User Datagram Protocol (UDP)
Translating between character streams and byte streams
Building a Server application that listens on a specified port
Building a Client application that establishes a connection with the Server and sends some text
Following by the second part :
Course Content
Module 1 - Java Database Connectivity (JDBC)
Describing the JDBC architecture
JDBC driver categories, including the JDBC-ODBC bridge and Type 4 drivers
Establishing a database connection
Creating and updating a database table
Using batch updates and prepared statements
Querying a database and extracting metadata
Using record locking and committing or rolling back a transaction
Handling SQL exceptions and obtaining the SQL state for single and chained exceptions
Module 2- The Java API for XML Processing (JAXP)
Explaining XML Document structure, namespaces and Document Type Definitions
Parsing XML data with the Simple API for XML Parsing (SAX)
Parsing XML data with the Document Object Model (DOM) and navigating through the DOM
Writing code to read an XML file into a database table
Reading a ResultSet from an SQL query into an XML DOM
Transforming an XML document using an XSL stylesheet
Module 3- Adding a Swing User Interface to the database application
Defining Model-View-Controller architecture
Using UML class diagrams to describe the types of objects in an application and their static relationships
Building a GUI using ?drag and drop? and understanding the underlying code
Using a TableModel object to parse and display XML data in a JTable
Building a client-side Controller object to interact with the database
Displaying input dialogs and message dialogs
Module 4- Remote Method Invocation
Describing the RMI architecture and the alternatives to RMI
Listing the steps involved in developing applications using RMI
Defining and implementing a remote interface
Generating stubs, starting the registry and registering objects
Looking up a remote object using the RMI protocol
Dynamically loading and instantiating class files from a web server
Implementing security with a policy file
Creating worker threads for time-consuming tasks
Module 5- Servlets and Web containers
Explaining the purpose and structure of a Servlet, and deploying a Servlet in a Web Container
Writing a Servlet that will return XML data from an SQL query sent over HTTP from a Web client.
Adding code to enable the Servlet to be accessed from the Swing application client built during previous modules
[ Note that, while Servlets are part of the Java 2 Enterprise Edition, this module may be useful to delegates who intend to deploy Java applications in a Web Container provided by their Internet Service Provider ]
Many thanks for any comment reagarding my query.
Kind Regards,

There's no game development!

Java KeyWord Explanation

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