Runtime objRuntime = Runtime.getRuntime();
            String strBackupString = "mysqldump -u " + userName + " -p" + password + " " + dbName;
            Process objProcess = objRuntime.exec(strBackupString);

This is used for backup of database. But what exactly happens? Can anybody make me explain, what is the purpose of Runtime and Process class?

Is this class used to act as if we are typing command from command prompt? Then what should i pass to objRuntime.exec() if i want to open notepad? And is the command executed as soon as we call exec method? If yes, then what purpose does Process serve here? I really can't understand these two classes. Please make me understand. Thanks in advance :)