# java > Java Application Launcher. > More information: . - Execute a java `.class` file that contains a main method by using just the class name: `java {{classname}}` - Execute a java program and use additional third-party or user-defined classes: `java -classpath {{path/to/classes1}}:{{path/to/classes2}}:. {{classname}}` - Execute a `.jar` program: `java -jar {{filename.jar}}` - Execute a `.jar` program with debug waiting to connect on port 5005: `java -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=*:5005 -jar {{filename.jar}}` - Display JDK, JRE and HotSpot versions: `java -version` - Display usage information for the java command: `java -help`