Could not find main class HelloWorld

Question

I installed Java 1.7.0 in the following folder C:\\Program Files\\Java. My operating system is Windows XP(Version 2002) with Service pack 3.

The envir

Answer 1

Java is not finding where your compiled class file (HelloWorld.class) is. It uses the directories and JAR-files in the CLASSPATH environment variable for searching if no -cp or -classpath option is given when running java.exe.

You don't need the rt.jar in the CLASSPATH, these was only needed for older versions of Java. You can leave it undefined and the current working directory will be used, or just add . (a single point), separated by ';', to the CLASSPATH variable to indicate the current directory:

CLASSPATH: .;C:\...\some.jar

Alternatively you can use the -cp or -classpath option:

java -cp . HelloWorld

And, as Andreas wrote, JAVA_HOME is not needed by Java, just for some third-party tools like ant (but should point to the correct location).