How to run the programs?

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A scientist has to learn how to use tools do do experiments. For example an astrophysicist knows a lot about telescopes. A biologist visualizes organic cells under a microscope. A programmer has lots of tools available to run computer programs. The programs are written in a programming language called Java version 1.5.

I know a person who knows about programming and Java
I want to learn how to run the programs by myself
    1. Install the Java Development Kit (JDK6) into your computer
    2. Download the programs from this website into your computer
    3. Compile the programs
    4. Execute the Java programs
What are all these names? Java - JDK - JRE - IDE - JVM - Compiler - Editor - Command line

I know a person who knows about programming and Java

Wonderful! Seek help from a teacher, a coworker or a friend familiar with programming. Show this web page to that person. Tell them you need help executing programs written in Java version 1.5. You will quickly be up and running.

I want to learn how to run the programs by myself

1. Install the Java Development Kit (JDK 6) into your computer

You need to install Java programming tools on your computer. These tools are free and can be downloaded from the Internet. You must download and install the free tool called Java SE Development Kit 6 (JDK 6). Your computer can then compile and execute the Java programs from the book. Follow these step by step instructions from the company that created the Java language. If you have a Windows computer follow "Hello World!" for Microsoft Windows

At this point you can compile and execute Java programs.

2. Download the programs from this website into your computer

On Windows open the console also known as the command prompt or command line.
Open the Command Prompt on a Windows computer

The following console opens up.
Console prompt is now ready

Create a directory named science under the C: drive. Type in the following four commands. After each command press the key 'Enter'.

cd c:\
mkdir science
cd science
dir

Create a directory science under C drive

The first command takes you at the top of the C drive.
Second command creates a subfolder named science.
Third command moves you into this newly created subfolder
Finally we verify this new directory is empty. We now are going to download Java programs into this location.

For the first activity right click on the following link PseudoRandom.java and save this file onto your computer to C:\science.
$Save downloaded Java program into C:\science folder$

In the command prompt, type in the following command again.

dir

In console prompt, verify the program has been downloaded with the command dir

The folder science now contains the java Program PseudoRandom.java downloaded from this website.

3. Compile the programs

Type in the following command. This runs the java compiler javac.exe and instruct it to compile the Java program PseudoRandom.java located in the current directory c:\science

javac PseudoRandom.java

If you get the following message 'javac.exe' is not recognized as an internal or external command you either did not install the JDK or the JDK's location is not set in your environment. Install the JDK following step 1 above. If you installed the JDK specify the exact location of the javac.exe java compiler program. For example the javac.exe can be found under "C:\Program Files\Java\jdk1.6.0_01\bin\javac" on my computer.

"C:\Program Files\Java\jdk1.6.0_01\bin\javac" PseudoRandom.java

Verify the Java program PseudoRandom.java was correctly compiled. At least one new file PseudoRandom.class should have been created by the Java compiler

dir

The compiler created the file PseudoRandom.class, PseudoRandom$Screen.class and PseudoRandom$Screen$1.class

4. Execute the Java programs

In the Command Prompt, type in the following command to execute the Java program PseudoRandom.class

java PseudoRandom

A new window appears with the name of the Java program. The program is successfully executing!
To stop the program click the red cross at the top right corner. You can then return to the Command Prompt and reexecute the program.
Note the command is java PseudoRandom. It is not java PseudoRandom.class. You must omit the '.class' extension even though this is really PseudoRandom.class that will be executed.
Note the current folder is the folder science that contains the Java program PseudoRandom.class. If the program is not in the current folder then the java.exe application will not be able to execute the Java program.

You can repeat steps 2 to 4 for each activity. All the files must be saved under the same folder.
$All Java programs are installed in the same folder c:\science$
Tip: you can compile all the java programs under the current folder with the following command

javac *.java

What are all these names? Java - JDK - JRE - IDE - JVM - Compiler - Editor - Command line

Java is the name of a programming language created in 1995. It is very popular among software companies and universities. It is also the name of the application used to execute Java applications. More...
JDK is an acronym for Java Development Kit. It is used to compile and execute Java programs. The book requires version 5 or above. More...
JRE is an acronym for Java Runtime Environment. It is used to execute Java programs. The book requires version 5 or above. More...
IDE is an acronym for Integrated Development Environment. It is a tool helping a programmer creating software programs. A Java IDE helps a programmer create Java programs. Programmers are often very passionate about their Java IDE because they spend many hours of their work life with it. There are many advanced tricks and features which makes life easier once you are familiar with them. Free Java IDEs include Eclipse, NetBeans and BlueJ. More...
JVM is an acronym for Java Virtual Machine. It is an application that knows how to execute Java class files. The Java class files can be used on any kind of computer however the computer needs the correct Java Virtual Machine to be able to execute it. This is why it is called 'virtual'. This application simulates a virtual machine that knows how to run Java class files . Windows, Linux and Mac computers have different Java Virtual Machines. The JRE includes a JVM named java or javaw. More...
Compiler is an application that converts text files created by a programmer into binary files the computer understands. A Java compiler converts a Java text file into a class file. The JDK includes a Java compiler application named javac that produces class files. The Java Virtual Machine knows how to execute class files.
Editor is an application used to edit text files. For Windows users, Notepad is the simplest editor and can be used to edit simple Java programs. Developers prefer using specific Java editors that color Java instructions such as 'for' 'if' 'else' making it easier to work with Java files. Java editors can even provide suggestions to complete what you are currently typing - this feature is called 'code assist'. Java IDE's provide powerful Java editors that also show the location of syntax errors. More...
Command line is an application used to type in commands to a computer. It is often used by developers to execute applications. If you don't use a Java IDE you can compile Java programs and execute them directly through the command line. You do so by calling the applications javac and java from the JDK and JRE and passing the name of the Java programs to compile or execute. More...