JasperFillManager.fillReport( rptPath, parameters, conn) The other gives a NoClassDefFoundError when I call Public static void main( String.Using Jasper Reports 1.3.2 in JSF web application. Let's see an example, suppose you have a class called HelloWorldApp inside a Java package called "beginner" in a working directory "C:\\practice" as shown below: As per my experience of more than 10 years in Java, this is the most common cause of "Exception in thread "main" : HelloWorldApp" error.įor beginners, it's seriously tricky to run a Java program from the command line due to classpath settings, it's even more tricky to run a class that is inside a package. Your class is inside a package and you are not providing the fully qualified name to java command while running it from the command prompt.
If this is your first Java program then there could be three main reasons for getting this error:ġ. It's not that intermediate and advanced Java programmer doesn't make mistakes, they do, but you will mostly see this error when you are trying to learn in Java the hard way i.e. Now let's see what are some common Java beginner's mistake or simply learning experience which causes this "Exception in thread "main" : HelloWorldApp".
#Filebot no class def found error how to
In this tutorial, we will try to find out what causes "Exception in thread "main" : helloworldapp/HelloWorldApp" when you run Java program from the command prompt and how to fix this error.Īs I said this error comes when you try to run your Java program from the command line but either doesn't have the class file, maybe not created yet, or Java is not able to find that due to incorrect Classpath settings. If you have not read already, I highly recommend reading my post on how classpath works in Java to understand it in a bit more detail.Ĭause of Exception in thread "main" : HelloWorldApp or, hence good knowledge of classpath is a must for any Java developer.
Unfortunately for beginners, the classpath is not an easy concept to grasp and it is also a source of many Java errors e.g. Eclipse takes care of setting up the classpath for you but when it comes to the command line, It's your job to make sure the required class is in Classpath. So, what is the difference in running the same Java program from Eclipse and from the command prompt? the answer is classpath. Since many Java programmer now days starts programming in Java directly from powerful IDEs like Eclipse, Netbeans, or IntelliJ IDEA, they face this kind of error whenever they try to run the Java program from the command line directly or via a script e.g. Technically, both errors come due to some reason and their solution is also exactly the same. Another interesting thing to remember is that this error only comes in Java version less than or equal to Java 6 like Java 1.5 or Java 1.4, if you are running in JDK 7 or Java 8 instead of this you will see "Error: could not able to find or load class HelloWorldApp". The name of the class could be different in each case, it depends upon which class you are passing to java command for running from the command prompt. class file is not there or Java is not able to find the class file due to incorrect classpath settings.
The "Exception in thread "main" : helloworldapp/HelloWorldApp" error comes when you are trying to run the HelloWorldApp Java program from the command line but either.
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