Cant compile and run java code in IntelliJ IDEA

Question

Using InteliJ IDEA version 12.1.6 I wanted to run the example from the Horstmann's 'Core Java' book:

public class Welcome
{
    public static void main(String[] args)
    {
        String[] greeting = new String[3];
        greeting[0] = "Welcome to Core Java";
        greeting[1] = "by Cay Horstmann";
        greeting[2] = "and Gary Cornell";

        for (String g : greeting)
        System.out.println(g);
    }
}

But I get the following error:

"C:\Program Files\Java\jdk1.7.0_45\bin\java" -Didea.launcher.port=7533 "-Didea.launcher.bin.path=C:\Program Files (x86)\IntelliJ IDEA\bin" -Dfile.encoding=UTF-8 -classpath "C:\Program Files\Java\jdk1.7.0_45\jre\lib\charsets.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\deploy.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\javaws.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\jce.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\jfr.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\jfxrt.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\jsse.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\management-agent.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\plugin.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\resources.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\rt.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\access-bridge-64.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\dnsns.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\jaccess.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\localedata.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\sunec.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\sunjce_provider.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\sunmscapi.jar;C:\Program Files\Java\jdk1.7.0_45\jre\lib\ext\zipfs.jar;C:\Program Files (x86)\IntelliJ IDEA\lib\idea_rt.jar" com.intellij.rt.execution.application.AppMain Welcome
Exception in thread "main" java.lang.ClassNotFoundException: Welcome
    at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:190)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:113)

Process finished with exit code 1

At the same time when compiling and executing a file in the command line everything is working correctly. Excuse me for such a question, I just started learning Java. :)

Answer 1

Sergey, it's look like you are working wrong with Idea. There is a step-by-step tutorial at wiki , that describes some basic concepts, about roots, run configurations, sdk-s and dependencies. It will be good, if you look at it. ( Exploring the project structure and Building(Running) the project especially)

IDE is a great helper to learn language, especially such intellegent one, as Idea, so, it will be a good start, to get familiar with it.

Basically, for a start, all your code(not compiled classes) must be under the source roots, and runConfiguration must specify application entry point (class with static void main() method).

You shouldn't think about class files, jar archives or command line tools, IDEA can do all this for you.

Better concentrate on learning, as I think!