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Compiling mutiple files from command line in Java

I am a beginner in Java and I've built a class "Employee" and a test program "EmployeeTest". From the command line, I have typed javac *.java.
It compiled both files and created Employee.class and EmployeeTest.class.
How do I run those now?
Thanks so much

Assuming Employee.class and EmployeeTest.class are in the same directory, and both do not specify package (they use default package) and EmployeeTest.class contains the main method...you can use this:
java EmployeeTest

The easiest way is to install an IDE which contain a compiler, interpreter, or both, such as NetBeans and Eclipse.
You will be able to run and compile your code easily.

You can run your application using the java <Classname> command. Replace the class name property with your own, e.g. EmployeeTest. If you are having problems, watch your case, since the class name is case sensitive. Also omit the .java file extension, Java needs to know the class name here.
So in your case, try running this from the command line:
java EmployeeTest

Why do I need to delete the package line to run Java outside of NetBeans?

So I'm completely new to programming, and I've been writing some Java with the NetBeans IDE. My code runs fine within NetBeans, but I've tried to run it using the command line as well. However, if I run it from the command line, I have to delete the line:
package firstprogram;
which NetBeans automatically places at the top of each new file, or I get the error:
Error: Could not find or load main class FirstProgram
However, if I do delete the line, then the program no longer runs within NetBeans! It doesn't seem right that I have to choose whether to run a .java from within NetBeans or without.
The research I've done makes me think that this is something to do with directory structure? But everything I read on that goes straight over my head. NetBeans has a structure with "build", "dist", "nbproject", and "src", but when I use the command line I just place the .java file in an empty directory and javac from there.
Any explanation is appreciated! The books and tutorials I'm learning from either assume you're just using NetBeans or don't have the package line at all.

You can compile your class using javac command from anywhere, as long as you provide correct relative or absolute path. The problems come when you want to run your program using the java program.
You have to provide the correct path corresponding to your package declaration. For example, if I had 'MyClass' in package mypackage, first line would look like this:
package mypackage;
class source stored on disk:
c:/MyNetbeansProject/src/mypackage/MyClass.java
Compiled bytecode:
c:/MyNetbeansProject/build/classes/mypackage/MyClass.class
Now, if I would have opened a command prompt/terminal in folder c:/MyNetbeansProject/build/classes/, I could run the program using java mypackage/MyClass or java mypackage.MyClass.
However, if i would be somewhere else, I would have to say where the class files are located using the cp option: java -cp c:/MyNetbeansProject/build/classes mypackage/MyClass. The path in cp option can be relative or absolute, use "" when it contains spaces.

Package are directory architecture.
If your class is in the package com.acme.test, the class should be in the com/acme/test directory.
Instead of placing your class in an empty folder, place it in a folder named firstprogram and do javac firstprogram/youclass.java
The package (and folder) permit you to arrange your architecture with logical pattern.
More info here : http://www.tutorialspoint.com/java/java_packages.htm

So like OcterA said, you should keep organized, but with only one class this is not the issue. I believe that your problem is that you are not entering the correct command into the command line.
First cd to the correct directory and when you want to execute a file within a package in that directory you need to enter
java packageName.className
In this case
java firstprogram.FirstProgram

Programming at compile time or at runtime

I have been reading many answers about the different between the compile time and the runtime in Java. But I am still not clear. Some answers said: the compile time is the period when you, the developer, are compiling your program or code. My question is when do I compile my program or code? For example: I open my IDE, eclipse or netbeans, write code in different classes and click on Run button and my application opens. Can someone explain me when did I compile my program/code in this sample process? or when was I in the compile time stage in this sample process?

When you write any java class,extension of file must be .java. Let take simple java class to print Hello World :
public class Simple {
public static void main(String[] args) {
System.out.println("Hello World !!");
}
}
So save this file as Simple.java.
Now open the cmd,lets say file saved in d:\test directory
d:\test>javac Simple.java // When you run this the .java is converted into byte code and it is saved in .class file.
d:\test>java Simple // JVM will execute the byte code file i.e. Simple.class
Note : All this process is done by IDE internally

Do this. Open notepad. Type in :
class Sampl{
public static void main(String []args){
System.out.println("hi from run time");
}
}
Save it as Sampl.java
Save it in a new folder without spaces - say c:\j\academic or ~/j/academic if on linux
Now open a command promot, figure out path to your JDK and type in
cd c:\j\academic
dir
Should see just Sampl.java
javac Sampl.java
dir
Should see 2 files :
Sampl.java and Sampl.class
That's you byte code
Now you can move or even delete Sampl.java and can still run Sampl.class from command line using
java -cp . Sampl
So you notepad and .java time was coding time. On command prompt was compile and run time
javac is the java compiler
java.exe is the runtime app that loads and runs our classes
[When runing jboss or other app container we run java with the jboss main class, and its calsses load and run ours]
These search results should help too google java tutorial command propmpt

There is a very important thing you may not have fully understood yet, namely that the text you type - which in this case makes a Java program - is not on the form of the instructions that the CPU is executing millions of every second - which for Java is Java Byte Code, and which needs to be present for the JVM to execute your program.
The transformation of the Java source code you wrote into the corresponding Java Byte Code, is done by a so-called Java compiler. There is nothing magical about a compiler as it is just a program which can read in text and generate the corresponding byte codes, and it is a standard assignment for computer science students to write one (but usually for smaller languages than Java).
If you write your programs in a standard text editor (not an IDE) and save to disk, you need to manually invoke the Java compiler by running javac on your Java sources. One of the advantages of IDE's is that they usually do the compilation automatically - either immediately when you save your file or when you want to run your program - but it makes it a bit more magical what goes on.
(Note: This transparent compilation step in an IDE becomes very useful when debugging in i.e. Eclipse, as it allows for updating the code being executed without having to restart the debug session from scratch.)

Having trouble compiling a Java program, I am new to it. Can't figure out what to do with directories

I have been searching the web trying to find the answer to my question, but everywhere I look seems to have too complex of a solution for a beginner like me. I have been working on this project, and just now realized that I should've made a package, or something like that. The thing is though, my program was working fine until I started dabbling with it, and now it won't work at all. I am getting this error:
Exception in thread "main" java.lang.NoClassDefFoundError: BubbleSort. class
Caused by: java.lang.ClassNotFoundException: BubbleSort.class
at java.net.URLClassLoader.findClass(URLClassLoader.java:434)
at java.lang.ClassLoader.loadClass(ClassLoader.java:672)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:358)
at ``java.lang.ClassLoader.loadClass(ClassLoader.java:638)
Could not find the main class: BubbleSort.class. Program will exit.
Here's how my "path" looks, if I am not mistaken. I am connected to my school's Z: drive through a remote connection, and from there I have a folder called myFirstname_Lastname_A4,
which then leads me to another folder called sortingzz which I believe is supposed to have only my source files, but it also ended up with my class files in there whenever I compiled. So here's what I am doing to compile.
cd myFirstname_Lastname_A4/sortingzz
javac *.java (Works fine, this is where I end up with my Class files inside of my sortingzz folder)
java * (This is where I get the error)
I am pretty sure I am just trying to run the program wrong. Before I started messing around with stuff I wasn't ready for, I used to just run the file with my main function in it, like this
javac SortingImplementation.java
java SortingImplementation
And that for the most part worked fine, but I started having trouble calling certain classes from other classes, so thats when I found out I was suppose to do the packaging and importing stuff.
In case that is the issue, I have on the top line of every source file:
package sortingzz;
and I am importing like this:
import sortingzz.*;
This is correct, right?
UPDATE:
I decided to give up on class pathing and trying to package everything, because as usual, I am getting responses that are way over my head, and to be honest I don't think it is necessary.
After removing package and importing from everything, and once again compiling using javac *., it actually compiles this time. However whenever I try to run my class with the main in it, SortingImplementation, it tells me that
Could not find the main class: SortingImplementation. Program will exit.
I don't get it, I am looking at the SortingImplementation.class right now, with all the other classes and java files, so I am not sure what it's trying to do.

javac *.java is fine. This will compile your files. However, you only need to run the file with your main method in it: java MainClass

You say that you are using packages to organize the classes. In this case you need to set the class path using the -cp flag.
javac -cp /path/to/parent/of/package classname.java
and
java classname
Also, your main class should be declared public and should have a main()

NoClassDefFoundError occures when a class was recognised in compile time but was not available during runtime.
So the JVM can't find your class in the classpath.
using -cp flag to specify where your package is should work.

the commanc javac *.java compiles all found java files to corresponding .class files. If you all your classfiles are in the same folder, which they should, you just run your regular java SortingImplementation command.
java * would, a bit depending on your OS, yield in an undesired command. For instance, on Linux it would be expanded by the OS to java SortingImplementation.java SortingImplementation.class BubbleSort. The last one is a directory, which ofcourse is not an executable class.

How do I run .class files on windows from command line?

I'm trying to run .class file from command line. It works when I manually move to the directory it's stored in, but when I try something like this:
java C:\Peter\Michael\Lazarus\Main
it says it can't find the main class. Is there any solution to this other than making a .jar file (I know that .jar is the best solution, but at this moment isn't the one I'm looking for)?

The Java application launcher (a.k.a java.exe or simply java) supports up to four different ways to specify what to launch (depending on which Java version you use).
Specifying a class name is the most basic way. Note that the class name is different from the file name.
java -cp path/to/classFiles/ mypackage.Main
Here we start the class mypackage.Main and use the -cp switch to specify the classpath which is used to find the class (the full path to the class mypackage.Main will be path/to/classFiles/mypackage/Main.class.
Starting a jar file.
java -jar myJar.jar
This puts the jar itself and anything specified on its Class-Path entry on the class path and starts the class indicated via the Main-Class entry. Note that in this case you can not specify any additional class path entries (they will be silently ignored).
Java 9 introduced modules and with that it introduce a way to launch a specific module in a way similar to how option #2 works (either by starting that modules dedicated main class or by starting a user-specified class within that module):
java --module my.module
Java 11 introduces support for Single-File Source Code Programs, which makes it very easy to execute Java programs that fit into a single source file. It even does the compile step for you:
java MyMain.java
This option can be useful for experimenting with Java for the first time, but quickly reaches its limits as it will not allow you to access classes that are defined in another source file (unless you compile them separately and put them on the classpath, which defeats the ease of use of this method and means you should probably switch back to option #1 in that case).
This feature was developed as JEP 330 and is still sometimes referred to as such.
For your specific case you'd use option #1 and tell java where to look for that class by using the -classpath option (or its short form -cp):
java -classpath C:\Peter\Michael\Lazarus\ Main
If your Main.java contains the entirety of your source code (and it is in the same directory), then you can use option #4, skip the compile step and directly compile-and-execute it:
java c:\Peter\Michael\Lazarus\Main.java

Assuming that Main.class does not have a package declaration:
java -cp C:\Peter\Michael\Lazarus\ Main
Java looks for classes in a "classpath", which can be set on the command line via the -cp option.

I just had the same issue, I tried running java hello.class, this is wrong.
The command should be java hello.
Do not include the file extension. It is looking for a class file, and will add the name on its own.
So running 'java hello.class' will tell it to go looking for 'hello.class.class' file.

Try this:
java -cp C:\Peter\Michael\Lazarus Main
You need to define the classpath.