Java program compiled under Ubuntu

Ubuntu under the Java program to compile the first need to install the JDK, and configure the corresponding environment variables under the simple HelloWorld example file named Helloworld.javajava code: Public classHelloWorld { Public Static voidMain (String args[]) {System. out. println ("Hello world!"); }} Compile: Javac Helloworld.java the HelloWorld is generated in the current folder.classfile run: Java HelloWorld Runtime If an error occurs: Cannot find or Load main class (and English error: Could not find or load mainclassHelloWorld the same) possible workaround:1. File name and class name are inconsistent, case-sensitive resolution: Modify the file name or class name to keep the two consistent2The environment variable is not set correctly so that the running program cannot find the specified main class workaround: A) Specify the main classpath by option for example: Java-classpath. HelloWorld (Specify current directory) b) If the file Helloworld.class is in the current working path, you can modify the environment variable to resolve sudo gedit/etc/Environment in CLASSPATH="***"Previous add":."(classpath=".:****"), that is, add the current work path to classpath immediately using environment variables: source/etc/Environment

Java program compiled under Ubuntu