I am a newbie java dev using netbeans IDE 7.1.1 and im watching this tutorial and right off the bat i get an error in my program even after 5 retypes to make sure its exactly the same as in the video so anyways this is the error
Error: Could not find or load main class javagame.JavaGame Java
Result: 1
and this is the code i have written
package JavaGame;
import javax.swing.JFrame;
public class JavaGame extends JFrame {
public JavaGame(){
setTitle("java game");
setSize(500, 500);
setResizable(false);
setVisible(true);
//setDefaultCloseOperation();
}
public static void main(String[] args){
}
}
You can find in this image how my project structure looks.
If that is an exactly copy-paste from your code, then your problem is with package name. Java is case sensitive and your package name is JavaGame so the qualified name of your class is JavaGame.JavaGame whilst the exception you get says that it can not find the class javagame.JavaGame.
Rename your package using Netbeans from JavaGame to javagame. That should fix the problem.
The problem is with your package name.. change the code at line1
package JavaGame;
package javagame;
NetBeans usually likes to use lower text for packages.
Hope this solves the problem. As the code runs on my machine.
Phil
Go to environmental variables and add path of JDK.
I got this error in past, and solved by setting classpath.
Related
I am using Netbeans 8.1 and Java 8.
I have a Java program named "MyFrame.java" and I want to create a package with its classes and methods - I call this package "myframe" and it is located at "\Lab\MyFrame\src\myframe". See picture:
(Ignore the red lines - this is a dummy version).
The class file is created after compiling, using the command "javac MyFrame.java", in the same directory \myframe. Now I want to import the package "myframe" in a new Java file "MoreButtons.java". So it would look like this and for convenience I save it in \src:
Compiling and executing MoreButtons.java works fine. The package has been imported. But now MyFrame.java is a bit trickier to execute: the naïve approach yields:
Translation: Error: Could not find or load main class
This seems to be quite a common problem and one of the solutions is simply to add the directory (\myframe) to the PATH environment variable. However, doing this still produced the error.
1) What am I doing wrong and how can I fix this?
2) What is the correct way to create and import custom-made packages in Java?
Make sure that terminal is at path Lab\MyFrame\src:
javac myframe\MyFrame.java MoreButtons.java
java -cp .; myframe.MyFrame
P.S. (/,:=linux/mac) or (\,;=windows)
MyFrame.java
package myframe;
public class MyFrame extends javax.swing.JFrame{
public MyFrame(String title){
super(title);
setSize(200,100);
setDefaultCloseOperation(DISPOSE_ON_CLOSE);
setLocationRelativeTo(null);
setVisible(true);
}
}
MoreButtons.java
public class MoreButtons {
public static void main(String[]args){
new myframe.MyFrame("More Buttons");
}
}
I used Edit plus to write the code:
import java.lang.System;
import java.lang.String;
class Test
{
public static void main(String[] args)
{
System.out.println("Hello World!");
}
}
After compiling it in command prompt with javac and executing with java commnds,
I am getting "Error: Could not find or load main class Test".
It was working fine in eclipse.
I even created path and classpath. But didn't work.
C:\Users\sss>cd C:\Users\sss\Desktop\Siri Study\java prog\ratanJprog
C:\Users\sss\Desktop\Siri Study\java prog\ratanJprog>javac Test.java
C:\Users\sss\Desktop\Siri Study\java prog\ratanJprog>java Test
Error: Could not find or load main class Test
Please help me. Thanks in advance.
Where you have written your code, go to that folder and type cmd in search bar see here and execute your pgm from there. I had faced same problem but that was solution for me.
you should change the class modifier to public
I am trying to do the free Stanford programming course online, but the programs wont run when executed. I believe I have successfully added the acm library to BlueJ, because when I compile the code, the imports are accepted, and it doesn't show any errors. But when I try and run the program, nothing happens, and all I see is the text, "Start: applet not initialized." Please, Please, Please help.
The code I am using in BlueJ is the following:
import acm.graphics.*;
import acm.program.*;
public class HelloProgram extends GraphicsProgram {
public void run() {
add(new GLabel("hello, world", 100, 75));
}
}
First of all you have to install the AMCInvoker extension, then you create an instance of your class HelloProgram and call the start method.
Currently trying to work with objects in Java. Everything goes fine until I hit compile. Have been reading a couple of other questions regarding the same problem, or the same given error, and at this point I am not sure wether I am forgetting something or that I need to change my classpath.
Main Class file:
package TesterClass;
public class Tester {
public static void main(String[] args){
TesterClass firstTest = new TesterClass();
firstTest.stringPrinter();
}
}
The file that is supposed to be functioning as a package file:
package TesterClass;
public class TesterClass{
private String workingSegment;
public TesterClass(){
workingSegment = "Working";
}
public void stringPrinter(){
System.out.println(workingSegment);
}
}
The 2 files are in the same directory and I am trying to manually compile them with
"javac Tester.java". The error I get is about the fact that its having issues with the package. All help is welcome!
EDIT: Forgot to post the actual compiler error.
Tester.java:9: cannot find symbol
symbol : class TesterClass
location: class TesterClass.Tester
TesterClass firstTest;
^
Tester.java:11: cannot find symbol
symbol : class TesterClass
location: class TesterClass.Tester
firstTest = new TesterClass();
^
2 errors
Move to the top of the source tree and compile both class...
So, assuming you source files are in \Java\TesterClass, you need to start in \Java
javac TesterClass\Tester.java TesterClass\TesterClass.java
You may also want to have a quick read of Code Conventions for the Java Programming Language as packages names are suppose to be in lower case :P
Updated
I just tried...
javac TesterClass\Tester.java
And it worked fine.
Are you sure that the Tester.java and TesterClass.java are in the TesterClass directory?
Updated with running example
So, basically, I dropped you .java files into the directory \compile under the TesterClass (\compile\TesterClass) directory and compiled them using...
\compile>javac TesterClass\Tester.java
Then I run them...
\compile>java TesterClass.Tester
Working
You need to go to the top of the directory hierarchy and first compile your TesterClass and then compile your Tester. Since you have not compiled your TesterClass yet, Tester is unable to find it.
The error clearly states that its not able to find the symbol TesterClass, and the reason being TesterClass hasn't been compiled yet.
I suggest you use an IDE which does the compilation automatically for you. If you stick to manual compilation, you need to compile all the classes in the proper order.
Try changing the package name so it does not match the class name. Right now they are the same. Make it package TesterClassPackage, then import TesterClass into the file with the main() method. Even though they are in the same package sometimes you need to literally import files even though they are in the same package.
javac TesterClass\TesterClass.java TesterClass\Tester.java
will do it
Recently I've made a Netbeans project and I am using SVN along with it. I am seeing duplicate class error, and in the console it says
java.lang.VerifyError: (class: pie/chart/explorer/PieChartExplorer, method: <init> signature: ()V) Constructor must call super() or this()
Could not find the main class: pie.chart.explorer.PieChartExplorer. Program will exit.
Exception in thread "main" Java Result: 1
Here is PieChartExplorer.java:
package pie.chart.explorer;
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
public class PieChartExplorer extends JFrame implements ActionListener {
JTextField one = new JTextField(10);
JTextField two = new JTextField(10);
JTextField three = new JTextField(10);
JButton sub = new JButton("Click to be amazed");
public PieChartExplorer() {
super("Pie Chart Explorer");
setSize(300,100);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
FlowLayout flo = new FlowLayout();
setLayout(flo);
setVisible(true);
add(one);
add(two);
add(three);
sub.addActionListener(this);;
add(sub);
}
public static void main(String[] args) {
PieChartExplorer app = new PieChartExplorer();
}
#Override
public void actionPerformed(ActionEvent e) {
Object source = e.getSource();
if(source == sub) {
try {
Pie show = new Pie(Float.parseFloat(one.getText()),Float.parseFloat(two.getText()),Float.parseFloat(three.getText()));
} catch(Exception ex) {
JOptionPane.showMessageDialog(this, "Please check entered data");
}
}
}
}
I have tried:
Clean and Rebuild project
Making sure that I have called super in all constructors
How can this be fixed? Code for download.
I found that renaming the package did not work, the old package was still there.
The problem for me started when I copied a package from another application into the current application, which already had a package with the same name. I was trying to add some missing classes to the package. After I did that, the error started.
To resolve it, I deleted the entire package from the target web app and did a clean and build. Then I copied the source package into the target application. No errors.
I saw these symptoms just the other day.
I had I file I had been editing and decided I wanted to split my changes into 2 commits. I went to the directory containing my file "x/y/Z.java", made a directory in "x/y" named "backup", moved "Z.java" there, and pulled a fresh copy from version control. Note all of this was done outside the IDE.
Back in the IDE I merged in the changes for the first commit and when I built I got the duplicate class message for "Z.java".
When I copied the source to "backup" I did it outside the IDE and it still had the original package "x.y" as did my newly edited "Z.java". NB would not compile the new "Z.java" because it could see it had already created "x.y.Z.class" (from "x/y/backup/Z.java").
There are 2 ways to fix this:
Rename "x/y/backup/Z.java" to "x/y/backup/Z.java.backup". (Prevent the backup copy from being compiled.)
Change the package in "x/y/backup/Z.java" from "x.y" to "x.y.backup". (Make the backup create a different class file.)
After making either of these changes, perform a "clean and build". Note: simply building will not fix the problem, you need to perform a clean to remove the rogue class file.
Note: #1 was done by renaming Z.java from the command line, not within NB. NB will not let you change the file extension.
Cleaning and Building solves the problem
If you still have the problem, this is how I solved it..
In my case I changed the class with main method later and the initial class was still referenced in the proporties file.
Change that setting, clean and build.. It worked for me...
In my case, i had the same problem in a Web application after making an external copy of a POJO and manually editing it outside NETBEANS. The problem actually was what the others suggested in other answers about a conflict in the already compiled .class files.
What i did to overcome this was simply delete the folder webAppname/WEB-INF/classes (where compiled classes reside) and then do a Clean and Build
Hope this helps someone