To start things off, I am entirely new to Java. I'm a C#/Powershell guy. A client at my IT Firm had an issue with a java program that they were executing on a daily basis that was having issues. According to Windows, the original program was written in April of 2011. I was able to unzip the file and pulled out all of the java files. I then rebuilt the program's structure in NetBeans and am getting ready to start editing. However, each *Test.java file is unable to import junit.framework.TestCase. In the original program file, each of these files were in the same folders as their associated files. From what I can tell, that is not best practices but it was the folder structure I found in the *.jar file I pulled them from. i.e.:
+ Source Packages
|
+--+ Folder
|
+--Example.java
|
+--ExampleTest.java
This leads me to 2 potential issues:
Reading similar threads regarding junit.framework "does not exist", there is mention of adding the junit.jar to the POM or adding the dependency to maven. For NetBeans, how do I do this? Using the "Add Dependency" menu, I am unable to find a "junit.framework" and there is 125,000 results for junit that I am unsure which one I need. Any insights? At the time of the original program's writing, v3 and v4 were both released, although v3.8.1 remained in use for some time beyond the adoption of v4.
For its use-case, see below. I assume all the errors are related to the junit import, so I included them as comments.
package com.example.program;
import java.util.Properties;
import junit.framework.TestCase;
/* Import files specific to program */
public class ExampleTest extends TestCase { //Cannot find symbol (class) "TestCase"
private Properties config = null;
#Override //Error: method does not override or implement a method from a supertype
/* SetUp function/method w/out any issues, creates config Properties object */
public void testExample(){
String line = "*"; // some csv line being parsed
CSVLine csvLine = new CSVLine(line, config);
assertEquals(/* does stuff */); // Error: cannot find "symbol" (method) "assertEquals"
assertTrue(/* does stuff */); // Error: cannot find "symbol" (method) "assertTrue"
assertTrue(/* does stuff*/); // Error: cannot find "symbol" (method) "assertTrue"
}
}
Do I need to move these Test.java files into a folder under the Test Packages section of the POM? Why would the original program have them in the same directory as their counterparts? Does some aspect of compiling/building move them to the same location?
ok i am a new one here and tried to write an awesome program:
package f;
import javax.swing.*;
public class dasMain {
public static void main(String[] args) {
ImageIcon img = new ImageIcon("pics/daFaq.png");
JOptionPane.showMessageDialog(null, img, "u r heck", JOptionPane.PLAIN_MESSAGE);
}
}
the thing is that if I run the program from Intellij Idea, then everything works fine, but after compilation the picture disappears
here are the source files of the project:
https://i.ibb.co/Njc8jYp/screen.png
i want to run this awesome code with pictures on other computers, but i only know this way and it doesn't work :(
You probably do not know where your program expects the picture to be. If you modify your code slightly, this information would be evident. Make use of
ImageIcon(URL)
File.toURI()
URI.toURL()
With that your code can look like this:
package f;
import javax.swing.*;
import java.io.File;
public class dasMain {
public static void main(String[] args) {
File png = new File("pics/daFaq.png");
System.out.println("Loading image from " + png.getAbsolutePath());
ImageIcon img = new ImageIcon(png.toURI().toURL());
JOptionPane.showMessageDialog(null, img, "u r heck", JOptionPane.PLAIN_MESSAGE);
}
}
Also I am pretty sure you intend to ship the png together with your code, so you better load it as a resource from the classpath. Here is an example.
I also investigated a bit why you would not see any error message or exception. This is documented in ImageIcon. So you might want to verify the image was loaded using getImageLoadStatus().
If you access the resource with the path like pics/file_name.png, then the pics - is the package name. And it must be located in the directory, marked as resource type. For example, create the directory, named resources in your project root, mark this directory as resource type, and move the pics there:
P. S. I would advise to use Maven or Gradle build system for managing project builds. As it is commonly accepted build management systems for the JVM projects. IDE New Project Wizard has the option to create Maven or Gradle based projects.
I have been working on an assignment for my class in programming. I am working with NetBeans. I finished my project and it worked fine. I am getting a message that says "No main class found" when I try to run it. Here is some of the code with the main:
package luisrp3;
import java.io.FileNotFoundException;
import java.io.PrintStream;
public class LuisRp3 {
public static void main(String[] args) throws FileNotFoundException {
java.io.File newFile = new java.io.File("LuisRamosp4.txt");
if (newFile.exists()) {
newFile.delete();
}
System.setOut(new PrintStream(newFile));
Guitar guitar = new Guitar();
I posted this before but had a couple issues. i have fixed the others and now have just this one remaining. Any advice will be greatly appreciated.
Right click on your Project in the project explorer
Click on properties
Click on Run
Make sure your Main Class is the one you want to be the entry point. (Make sure to use the fully qualified name i.e. mypackage.MyClass)
Click OK.
Run Project :)
If you just want to run the file, right click on the class from the package explorer, and click Run File, or (Alt + R, F), or (Shift + F6)
Also, for others out there with a slightly different problem where Netbeans will not find the class when you want when doing a browse from "main classes dialog window".
It could be that your main method does have the proper signature. In my case I forgot the args.
example:
public static void main(String[] args)
The modifiers public and static can be written in either order (public static or static public), but the convention is to use public static as shown above.
Args: You can name the argument anything you want, but most programmers choose "args" or "argv".
Read more here:
http://docs.oracle.com/javase/tutorial/getStarted/application/
When creating a new project - Maven - Java application in Netbeans
the IDE is not recognizing the Main class on 1st class entry. (in Step 8 below we see no classes).
When first a generic class is created and then the Main class is created Netbeans is registering the Main class and the app could be run and debugged.
Steps that worked for me:
Create new project - Maven - Java application
(project created: mytest; package created: com.me.test)
Right-click package: com.me.test
New > Java Class > Named it 'Whatever' you want
Right-click package: com.me.test
New > Java Main Class > named it: 'Main' (must be 'Main')
Right click on Project mytest
Click on Properties
Click on Run > next to 'Main Class' text box: > Browse
You should see: com.me.test.Main
Select it and click "Select Main Class"
Hope this works for others as well.
The connections I made in preparing this for posting really cleared it up for me, once and for all. It's not completely obvious what goes in the Main Class: box until you see the connections. (Note that the class containing the main method need not necessarily be named Main but the main method can have no other name.)
I had the same problem in Eclipse, so maybe what I did to resolve it can help you.
In the project properties I had to set the launch configurations to the file that contains the main-method (I don't know why it wasn't set to the right file automatically).
In project properties, under the run tab, specify your main class.
Moreover, To avoid this issue, you need to check "Create main class" during creating new project. Specifying main class in properties should always work, but if in some rare case it doesn't work, then the issue could be resolved by re-creating the project and not forgetting to check "Create main class" if it is unchecked.
If the advice to add the closing braces work, I suggest adding indentation to your code so every closing brace is on a spaced separately, i.e.:
public class LuisRp3 {
public static void main(String[] args) throws FileNotFoundException {
// stuff
}
}
This just helps with readability.
If, on the other hand, you just forgot to copy the closing braces in your code, or the above suggestion doesn't work: open up the configuration and see if you can manually set the main class. I'm afraid I haven't used NetBeans much, so I can't help you with where that option is. My best guess is under "Run Configuration", or something like that.
Edit: See peeskillet's answer if adding closing braces doesn't work.
There could be a couple of things going wrong in this situation (assuming that you had code after your example and didn't just leave your code unbracketed).
First off, if you are running your entire project and not just the current file, make sure your project is the main project and the main class of the project is set to the correct file.
Otherwise, I have seen classmates with their code being fine but they still had this same problem. Sometimes, in Netbeans, a simple fix is to:
Copy your current code (or back it up in a different location)
Delete your current file
Create a new main class in your project (you can name it the old one)
Paste your code back in
If this doesn't work then try to clear the Netbeans cache, and if all else fails, then just do a clean un-installation and re-installation of Netbeans.
In the toolbar search for press the arrow and select Customize...
It will open project properties.In the categories select RUN.
Look for Main Class.
Clear all the Main Class character and type your class name.
Click on OK.
And run again.
The problem is solved.
If that is all your code, you forgot to close the main method.
Everything else looks good to me.
public class LuisRp3 {
public static void main(String[] args) throws FileNotFoundException {
java.io.File newFile = new java.io.File("LuisRamosp4.txt");
if (newFile.exists()) {
newFile.delete();
}
System.setOut(new PrintStream(newFile));
Guitar guitar = new Guitar();
}}
Try that.
You need to add }} to the end of your code.
You need to rename your main class to Main, it cannot be anything else.
It does not matter how many files as packages and classes you create, you must name your main class Main.
That's all.
import java.util.Scanner;
public class FarenheitToCelsius{
public static void main(String[]args){
Scanner input= new Scanner(System.in);
System.out.println("Enter Degree in Farenheit:");
double Farenheit=input.nextDouble();
//convert farenheit to celsius
double celsuis=(5.0/9)*(farenheit 32);
system.out.println("Farenheit"+farenheit+"is"+celsius+"in celsius")
{
I also experienced Netbeans complaining to me about "No main classes found". The issue was on a project I knew worked in the past, but failed when I tried it on another pc.
My specific failure reasons probably differ from the OP, but I'll still share what I learnt on the debugging journey, in-case these insights help anybody figure out their own unique issues relating to this topic.
What I learnt is that upon starting NetBeans, it should perform a step called "Scanning projects..."
Prior to this phase, you should notice that any .java file you have with a main() method within it will show up in the 'Projects' pane with its icon looking like this (no arrow):
After this scanning phase finishes, if a main() method was discovered within the file, that file's icon will change to this (with arrow):
So on my system, it appeared this "Scanning projects..." step was failing, and instead would be stuck on an "Opening Projects" step.
I also noticed a little red icon in the bottom-right corner which hinted at the issue ailing me:
Unexpected Exception
java.lang.ExceptionInInitializerError
Clicking on that link showed me more details of the error:
java.security.NoSuchAlgorithmException: MD5 MessageDigest not available
at sun.security.jca.GetInstance.getInstance(GetInstance.java:159)
at java.security.Security.getImpl(Security.java:695)
at java.security.MessageDigest.getInstance(MessageDigest.java:167)
at org.apache.lucene.store.FSDirectory.<clinit>(FSDirectory.java:113)
Caused: java.lang.RuntimeException
at org.apache.lucene.store.FSDirectory.<clinit>(FSDirectory.java:115)
Caused: java.lang.ExceptionInInitializerError
at org.netbeans.modules.parsing.lucene.LuceneIndex$DirCache.createFSDirectory(LuceneIndex.java:839)
That mention of "java.security" reminded me that I had fiddled with this machine's "java.security" file (to be specific, I was performing Salvador Valencia's steps from this thread, but did it incorrectly and broke "java.security" in the process :))
Once I repaired the damage I caused to my "java.security" file, NetBeans' "Scanning projects..." step started to work again, the little green arrows appeared on my files once more and I no longer got that "No main classes found" issue.
Had the same problem after opening a project that I had downloaded in NetBeans.
What worked for me is to right-click on the project in the Projects pane, then selecting Clean and Build from the drop-down menu.
After doing that I ran the project and it worked.
Make sure the access modifier is public and not private. I keep having this problem and always that's my issue.
public static void main(String[] args)
I am trying to add instant app functionality to my project. So I am following the instructions given in this tutorial : https://codelabs.developers.google.com/codelabs/android-instant-apps/#0
The fifth chapter explains how to move the existing code from an application module to a feature module. I'm following this tutorial step-by-step, updating both the playground topeka project given with this tutorial and my project. However, I'm stuck after the first sub-chapter "Convert the app module into a feature module called topeka-base".
After renaming my project folder to project-base, and transforming it from com.android.application to com.android.feature, the Gradle sync runs fine but I can't rebuild my project anymore, since every occurrence of my.project.R get a Cannot resolve symbol 'R' error. I'm not having this problem with the topeka app that comes along with the tutorial, however.
As you can see below, there is no such error in topeka project:
So I tried looking at my project generated files to find a difference, but actually I don't see any difference with topeka:
package my.project;
public final class BuildConfig {
public static final boolean DEBUG = Boolean.parseBoolean("true");
public static final String APPLICATION_ID = "my.project";
public static final String BUILD_TYPE = "debug";
public static final String FLAVOR = "";
public static final int VERSION_CODE = 38;
public static final String VERSION_NAME = "1.9.0";
}
So what could be the reason? Thanks for your help.
You can first start with trying to clean and then rebuild the project sometimes it fixes the issue.
You can also try invalidating the caches and restarting the android studio.
Also, I guess you should check the manifest file and edit the app's name there.
I developer a basic Processing PApplet to run as a Tool in the Arduino IDE and that ran fine until Arduino 1.5.8. The problem I have is that in Arduino 1.6.0 some of the code got refactored and this happened on the Arduino side:
" In order to provide a better command line, IDE has been refactored
into app and arduino-core which is the old core In order to avoid
conflicts between classes, PApplet was moved from
processing.core.PApplet to processing.app.legacy.PApplet "
This explanation came from one of the Arduino IDE developers. It's worth noting that processing.app.legacy.PApplet is a (very)stripped down version of PApplet, discarding all graphics capabilities which I need.
Initially I was getting this error:
Uncaught exception in main method: java.lang.NoClassDefFoundError: processing/core/PApplet
Placing Processing's core.jar in the same location as the eclipse exported tool jar fixed this issues, but let to another:
Exception in thread "AWT-EventQueue-0" java.lang.RuntimeException: You need to use "Import Library" to add processing.core.PGraphicsJava2D to your sketch.
at processing.core.PApplet.makeGraphics(Unknown Source)
at processing.core.PApplet.init(Unknown Source)
The part that is confusing is I've used Processing's library source java files instead of the core.jar compiled library to avoid this issue, but it didn't change anything.
I've gone through PApplet's source code and found the graphics/renderer class gets loaded and instantiated at runtime here like so:
Class<?> rendererClass =
Thread.currentThread().getContextClassLoader().loadClass(renderer);
Constructor<?> constructor = rendererClass.getConstructor(new Class[] { });
PGraphics pg = (PGraphics) constructor.newInstance();
and this is where the ClassNotFoundException is caught throwing the Runtime exception:
catch (ClassNotFoundException cnfe) {
// if (cnfe.getMessage().indexOf("processing.opengl.PGraphicsOpenGL") != -1) {
// throw new RuntimeException(openglError +
// " (The library .jar file is missing.)");
// } else {
if (external) {
throw new RuntimeException("You need to use \"Import Library\" " +
"to add " + renderer + " to your sketch.");
} else {
throw new RuntimeException("The " + renderer +
" renderer is not in the class path.");
}
}
I'm getting more comfortable with java, but I don't have enough experience to figure this one out. It looks like a classpath issue, but I'm not sure why this happens and how I should tell java where to find the classes it needs to load.
Here is the code test I'm using based on the Arduino Tool sample that comes with the IDE. Currently I'm exporting the jar file (not runnable) from eclipse:
/*
Part of the Processing project - http://processing.org
Copyright (c) 2008 Ben Fry and Casey Reas
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
package com.transformers.supermangletron;
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import processing.core.PApplet;
import processing.app.Editor;
import processing.app.tools.Tool;
//import processing.app.legacy.PApplet;
/**
* Example Tools menu entry.
*/
public class Mangler implements Tool {
private Editor editor;
public void init(Editor editor) {
this.editor = editor;
}
private void setupSketch(){
int w = 255;
int h = 255;
// PApplet ui = new PApplet();
TestApp ui = new TestApp();
JFrame window = new JFrame(getMenuTitle());
window.setPreferredSize(new Dimension(w,h+20));
window.add(ui);
window.invalidate();
window.pack();
window.setVisible(true);
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ui.init();
System.out.println("setup complete");
}
public String getMenuTitle() {
return "Mangle Selection";
}
public void run() {
setupSketch();
}
}
and here's the basic test Applet I'm trying to display:
package com.transformers.supermangletron;
import processing.core.PApplet;
public class TestApp extends PApplet {
public void setup(){
size(100,100);
}
public void draw(){
background((1.0f+sin(frameCount * .01f)) * 127);
}
}
How can I fix this ClassNotFoundException with my setup?
Any hints on what I should double check regarding class paths?
If you're getting this error when you run from eclipse, you have to add the library jars to your classpath. You do this by right-clicking your project, going to properties, then to Java Build Path. Make sure the library jars are listed under the Libraries tab.
If you're getting this error when you run an exported jar, then you need to do one of two things:
Either make sure you export a runnable jar with the library jars embedded inside the main jar. Do this from eclipse by right-clicking the project, going to Export, then choosing "runnable jar" from the list.
Or, make sure you set the classpath as a JVM argument. You do this using the -cp option from the command line.