What does it mean in netbeans when a statement like the code below becomes all italic?
MessageBox.show("test", "test");
I get the error below as well on runtime. But not when coding, just the ".show()" method that's not appearing in autocomplete. But the class is already in its appropriate folder and is already imported. What could be the problem here as well?
Uncompilable source code - Erroneous sym type: library.MessageBox.show
Complete code:
public class MessageBox {
public static void show(String titleString, String messageString)
{
JOptionPane.showMessageDialog(null, messageString, titleString, JOptionPane.INFORMATION_MESSAGE);
}
}
The above code you provided runs fine on eclipse.
As you said you are using Netbeans and may be affected by a bug. Try this:
Open the project properties, select the Build-Compiling, uncheck
"Compile on save" and rerun the application.
This will make sure all your source code becomes recompiled before running it.
Ref: https://netbeans.org/community/news/show/1647.html
Eclipse give error when I try to compile and run to JAVA codes. The error is
"The selection cannot be launched, and there are no recent launches".
How to fix this issue ??
your code is wrong. you need a main method to launch your program
package main;
public class main {
public static void main (String[] args) {
System.out.println("Test");
}
}
Note: The name of the class always has to be the name of the file, and typically java classes start with an uppercase letter
I think you should run main first and describe your problem in more detail if you still have a problem.
Q: When I try to run my project by clicking the green "Play" button, I get an error of, "The Selection cannot be launched, and there are no recent launches."
A: See previous question. You must run your project's "Main" class at least once by using the right-click method described above, before the "Play button" to run a project will work.
http://courses.cs.washington.edu/courses/cse143/15wi/eclipse_tutorial/faq.shtml
I'm doing a processing based project with eclipse and Procliping. When I'm testing the project with "Run" command inside the IDE, everything works fine. But if I export it into a runable-jar, when I run the jar it'll give this error on the line String[] li=Serial.list();. Any idea what's going wrong?
Java source attachment is "processing-2.2.1/modes/java/libraries/serial/src"
And here is a sample code:
package abcd;
import processing.core.PApplet;
import processing.serial.Serial;
public class TestUI extends PApplet {
Serial port;
public void setup(){
System.out.println(Serial.list());
}
public void draw(){
}
public static void main(String _args[]) {
PApplet.main(new String[] { abcd.TestUI.class.getName() });
}
}
My approach of solving it:
Download the latest version of java-simple-serial-connector(Which is the base library used for Processing's serial library), replace jssc.jar in the lib folder, and the error will be gone, and my application runs smoothly.
However the base library is 4 times bigger than the modified version used in Processing, so there may be some unnecessary features involved.
Seems like in their latest alpha version, Processing solved the same problem for exporting apps(at least in windows) by adding more look-up paths, while keeping their Serial library intact. I'm not familiar with their development environment, so I didn't look further into it. There may be a simpler solution.
I am a beginner studying Java using NetBeans. I created my first class and some simple code:
public class suju {
public static void main(String[] args){
System.out.print("hello word");
}
}
Why don't I see any result when I click run? I am supposed to see hello world but nothing like this is shown.
Only a message BUILD SUCCESSFUL (total time: 0 seconds)
Unfortunately, I can't post images yet to better present the problem I am facing.
Try to right click on the class file on the left panel then choose run option
Mine was doing the same.
I went to java.com and downloaded java again- it then prompted me to uninstall all out-if-date updates.
When I ran it again it was working.
My DrJava was working fine, but now I keep getting the folowing error whenever I run anything:
Static Error: This class does not have a static void main method accepting String[].
So it will compile OK, but then it shoots out the error . This happens even though everything I test does indeed have a public static void main(String[] args) in it. It seems like a classpath/resources type of error. I appreciate any tips
EDIT: my class
public class Test{
public static void main(String[] args){
System.out.println(" hashmap ");
}
}
There's nothing wrong with the code, so the problem must be with the environment.
Check that you're actually executing that class. Find out where the class that's executed is specified and check it's correct
Check that you're compiling the class. Maybe the code you're looking at has not been compiled and you're trying to execute an old version that was compild before you coded a main()
Check your classpath. Is the compiled class accessible in the classpath of the java command
You don't need to reinstall java, nor is it a java version issue. It may be the way that your are running the program.
To check if it is a problem with your code, do the following:
Make a new folder and put Test.java in it.
Open up Command Line Or Terminal and change to that folder .
Type javac Test.java. Test.class should be in the folder now.
If you want, open up the class with a text editor. This is what I get:
˛∫æ2
<init>()VCodeLineNumberTablemain([Ljava/lang/String;)V
SourceFile Test.java hashmap Testjava/lang/Objectjava/lang/SystemoutLjava/io/PrintStream;java/io/PrintStreamprintln(Ljava/l ang/String;)V! *∑±
% ≤∂±
Back to the command line or terminal, type java Test.
If you get an error, which you shouldn't, I don't know what to say. It should produce the string " hashmap " on to the command line or terminal.
Why re-installing Dr. Java may not work is because you may be using the same working directory, causing same run settings to be used. Dr. Java may be running an external program, one without a main method.
I think that you should install the Eclipse IDE for Java. It is much easier to get around, it looks nicer, and it runs the file or project that you are looking at currently.
Sometimes this problem happens because may be mistake in saving file.you always your file using double quotes and with the .java extension which is main class means that class containing main method.
you should save your file by class name which is public .if there is two classes and both have main method then you should save your file by class name that is public and that class will be run.As like your compiler looking for main method in public static void main(String [] args) that is contract for jvm to run a programme
so it is not able to found that main method that is static and it looking for your Dr class.java
See this Example it have two main methods and practice these kinds of question.I also got this kind of problem in starting.
public class TestFirst
{
public static void main(String [] args){
System.out.println(" TestFirst ");
}
}
class Test{
public static void main(String [] args){
System.out.println(" hashmap ");
}
}
if you save pro-gramme by "TestFirst.java" then o/p will come TestFirst if you do some mistake in main method because we have saved our programme by TestFirst then you will get error like you got.
# 2nd mistake may be this
debian#debian:~/Geany_java$ javac Test1.java
debian#debian:~/Geany_java$ java Test1
Exception in thread "main" java.util.NoSuchElementException
at java.util.StringTokenizer.nextToken(StringTokenizer.java:349)
at Test1.main(Test1.java:11)
your classpath has not set properly See above Compiling successfully but running showing same kind of error you got.Which OS is using I can guide you properly.
Check that actually your file have the .java termination nor the .dj
There is nothing wrong with the code.
It is the executing environment which might have problem. Please share the details.
Check if program compiled correctly.
Check time-stamo of .class file.
Check permissions on folder/directory where class-files are getting generated.
Check if DrJAVA has appropriate permission on the directory.
Did you create a file, compiled it with out main?
Check class-path. Might be possible that previous class file is still being found by JDK in classpath.
Try compiling .java file from cmdLine instead of editor.
As others have mentioned, your code is fine. There must be a problem with your environment. I recently experienced a similar issue when investigating and answering this question.
Basically, in that question, the code Void.class instanceof Class resulted in a compiler error because a user-made Class.class existed in the classpath, so one Class (the Java built-in java.lang.Class) didn't match with the given Class (user-made).
Something similar may be at work here. It is possible that there is a user-made String.class in your classpath. Then in your main signature, String[] args would mean an array of your String, when Dr. Java must be looking for a main method taking an array of the Java built-in String, i.e. java.lang.String[]. If you have a custom String class in your classpath (or in your project?), then the Java compiler will choose it over the built-in String. If you were to compile and run your Test class from the command line, then you would get the runtime error: Exception in thread "main" java.lang.NoSuchMethodError: main.
Following #S0urceC0ded's suggestion, you may find this when looking at Test.class in a text editor:
main([LString;)V // A user-made String class
instead of what it's supposed to be:
main([Ljava/lang/String;)V // The built-in java.lang.String class
If so, remove your own String class (at least the .class file, but also the .java file so the .class file isn't re-created) from the classpath, and compile and run your Test class again.
Without a look at your environment, I can't tell for sure that this is the issue. But it can explain it.
If you are using Dr.Java as IDE, then you need to make sure that the main class containing 'public static void main' should be at the very top of your program. Otherwise Dr.Java throws this error during runtime.