You cannot run a file compiled using NetBeans because :
while creating new file in netbeans we always first make a new project which automatically creates a new package
the package which is created is automatically added at the top of each of the file made using netbeans eg:
Package javaapplication3;
/**
*
* @author Rajeev Handa
*/
public class JavaApplication3 {
/**
* @param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
int i=10;
System.out.println(i);
}
}
In this case the default package made in netbeans is 'javaapplicatiion3'
so to run a program in cmd prompt first of all:
Copy the [abc].java file into the bin folder of jdk
Open the file and edit it with notepad
remove the name of the package i.e. Package javaapplication3
Then press Ctrl+S
Open cmd Prompt
Go to the bin folder or locate it by typing [cd..] command eg:cd java [enter] cd jdk[enter] cd bin[enter]
Type javac [name_of_file].java
You will see that a class file gets created in bin folder
First of all, you need to understand the correct way to launch a program using the java (or javaw) command.
The normal syntax1 is this:
java [<option>...]<class-name>[<argument>...]
where is a command line option (starting with a "-" character), is a fully qualified Java class name, and is an arbitrary command line argument that gets passed to your application.
1 - There is a second syntax for "executable" JAR files which I will describe at the bottom.
For example:
java -Xmx100m com.acme.example.ListUser fred
What this is going to do is the following:
Search for the compiled version of the com.acme.example.ListUser class.
Load the class.
Check that the class has a main method with signature static void main(String[]).
Call that method passing it the command line arguments as a String[].
Reasons why Java cannot find the class
When you get the message "Could not find or load main class ...", that means that the first step has failed. The java command was not able to find the class. And indeed, the "..." in the message will be the fully qualified class name that java is looking for.
So why might it be unable to find the class? Basically, there are two main causes:
The first likely cause is that you may have provided the wrong class name. (Or ... the right class name, but in the wrong form.) Considering the example above, here a variety of wrong ways to specify the class name:
Example #1 - a simple class name:
java ListUser
When the class is declared in a package such as com.acme.example, then you must use the full classname including the package name in the java command; e.g.
java com.acme.example.ListUser
Example #2 - a filename or pathname rather than a class name:
Example #3 - a class name with the casing incorrect:
java com.acme.example.listuser
Example #4 - a typo
java com.acme.example.mistuser
The second likely cause is that the class name is correct, but that the java command cannot find the class. To understand this, you need to understand the concept of the "classpath". This is explainedwell by the Oracle documentation:
So ... if you have specified the class name correctly, the next thing to check is that you have specified the classpath correctly:
Read the three documents linked above. (Yes ... READ them.)
Look at command line and / or the CLASSPATH environment variable that is in effect when you run the java command. Check that the directory names and JAR file names are correct.
If there are relative pathnames in the classpath, check that they resolve correctly ... from the current directory that is in effect when you run the java command.
Check that the class (mentioned in the error message) can be located on the effective classpath.
Additional Notes:
When you put a directory on the classpath, it notionally corresponds to the root of the qualified name space. Classes are located in the directory structure beneath that root, by mapping the fully qualified name to a pathname. So for example, if "/usr/local/acme/classes" is on the class path, then when the JVM looks for a class called com.acme.example.Foon, it will look for a ".class" file with this pathname:
If you had put "/usr/local/acme/classes/com/acme/example" on the classpath, then the JVM wouldn't be able to find the class.
The classpath needs to include all of the other (non-system) classes that your application depends on. (The system classes are located automatically, and you rarely need to concern yourself with this.)
The java -jar syntax
The alternative syntax used for "executable" JAR files is as follows:
java -Xmx100m-jar /usr/local/acme-example/listuser.jar fred
In this case the name of the entry-point class (i.e. com.acme.example.ListUser) and the classpath are specified in the MANIFEST of the JAR file.
IDEs
A typical Java IDE has support for running Java applications in the IDE JVM itself or in a child JVM. These are generally immune from this particular exception, because the IDE uses its own mechanisms to construct the runtime classpath, identify the main class and create the javacommand line.
However it is still possible for this exception to occur, if you do things behind the back of the IDE to break things. For example, if you have previously set up an Application Launcher for your Java app in Eclipse, and you then moved the JAR file containing the "main" class to a different place in the file system without telling Eclipse, Eclipse would unwittingly launch the JVM with an incorrect classpath.
In short, if you get this problem in an IDE, check for things like stale IDE state and broken project references or launcher configurations.
Monday, 12 January 2015
Variable Already Defined Error In Netbeans!!!
Sometimes there occurs a error while compiling .jsp file:
Compiling 2 source files to C:\Users\Rajeev Handa\Documents\NetBeansProjects\Mission Cricket new\build\generated\classes C:\Users\Rajeev Handa\Documents\NetBeansProjects\Mission Cricket new\build\generated\src\org\apache\jsp\playersdeatil1_jsp.java:32: error variable PATH is already defined in class playersdeatil1_jsp String PATH="jdbc:mysql://localhost/";
^
1 errors C:\Users\Rajeev Handa\Documents\NetBeansProjects\Mission Cricket new\nbproject\build-impl.xml:953:The following error occurred while executing this line: C:\Users\Rajeev Handa\Documents\NetBeansProjects\Mission Cricket new\nbproject\build-impl.xml:296: Compile failed;see the compiler error output for details. BUILD FAILED (total time: 1 second)
This error usually occurs when any net beans failed to compile any file successfully and during compilation of different file the next time it fails to remove from its cache the previous contents .
So to remove this error look at the very first line of the error very carefully because the cause of the error is usually defined in the first line.
In this case see the first line which says :"\build\generated\src\org\apache\jsp\playersdeatil1_jsp.java"
Now the erroneous file is located somewhere in the path specified
So go to the path specified and delete the error causing file
Note:Removing the erroneous file does not harm UR file because it is related to the the server not the compiler itself So The best way is to locate the path and remove the error causing file
Sunday, 11 January 2015
Accidentally Removed .exe file from computer or Accidentally disable common file association types to be automatically loaded during win start up??
If You accidentally removed common file association types to be automatically loaded into memory during window start up you can easily repair it
Go to this Link and download the zip file by choosing the file type that you have accidentally removed or is being corrupted .Download that file "http://www.winhelponline.com/blog/file-asso-fixes-for-windows-7/"
Open the download folder and extract the contents on desktop
Open registry settings by using run>>regedit.exe
Go to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts
Choose the file extension you have accidentally removed and go to File>>import...
Select the file from desktop and press import..
Thats it....
Saturday, 27 December 2014
How to tackle error with Wamp/Xamp server??
Server Error in Application "DEFAULT WEB SITE"Internet Information Services 7.5
Make sure no other program conflict wamp such as Xampp, phpEasy, IIS, Skype, Zonealarm, firewall/antivirus, NOD32, Eset, any web and/or Remote Desktop related program, such as Teamviewer ...
IIS and Apache/Wamp are both web server and might conflict in some way, so you have to disable IIS in order for Wamp to work
Disable IIS in Vista/W7:
Control Panel, Uninstall Programs, Turn Widows Features On or Off, uncheck Internet Information Services
Disable IIS in XP:
Control Panel, Add/Remove Programs, Add/Remove Windows Components, uncheck Internet Information Services (IIS)
Restart computer, then restart Wamp
Also, in folder C:\WINDOWS\System32\drivers\etc, open file hosts and delete anything in this file and have only this line below and nothing else
127.0.0.1 localhost
If using Skype, go to Tools->Options->Advanced->Connection and uncheck the box "Use 80 and 443 as alternatives for incoming connections". Restart Skype after WAMP. Now you will be able to use both programs at the same time w/o problems
How to add border outside a form in html ?
.here's the same form as above using the commands we'll hit today.
The Tags
Take a good long look at the form above. You should be able to get it, and this text, on your screen at the same time. Notice that I grouped elements together by drawing a lined box around them. Remember that you can place as many form elements inside the lined box you want. The elements will react to HTML just like they always did, it's just that you've drawn a line around them.
In addition to the line, I've added a title in bold. The title text is placed in the upper left hand of the lined box by default. I used tags to make the text bold. Now the tags:
You can pretty much take it from here, but let's take a look at the code that created the first little section that surrounds the two text boxes:
Follow that pattern again and again grouping form elements as you wish. No sweat.
Use A Table Too
I know this reads like it is in direct contradiction to what I wrote about tables and forms up above, but hear me out. Notice how the FIELDSET table is confined to only 375 pixels wide. It is that way because I surrounded the entire form with a single table cell with the width set to 375. Please note that I said a single table cell. That's the key.
It was done purely for aesthetics. If you don't surround the form with a table cell, the lined box runs the length of the browser screen. If there's a way to stop the box from doing that without using a table cell, I couldn't find it. Even examples on the MSIE site showed a table being used to confine the width of the box. My reference book suggests that the attributes ALIGN and WIDTH work with the FIELDSET tag. I tried to get them to work time and time again. No dice.
