It is conventional for a class name to start with a capital letter, but this is not required by the compiler. The remaining characters can be a mix of alphabetic characters, digits, underscore, and dollar sign $.В No spacesВ are allowed inside an identifier. The first character of an identifier cannot be a digit. In programming, theВ name for something is called an identifier.В An identifier is one or more characters long. The name of the class (and therefore the name of the file) is up to you.

Most classes contain many more lines than this one.В Everything that makes up a class is placed between the first brace В . What is the name of the bytecode file the compiler creates?.What is the name of the bytecode file the compiler createДЈ.Here is the first line of another Java program: public class AddUpNumbers When the program is compiled the compiler creates a file of bytecodes called Hello.class. Says that this source program defines a class called Hello.В A classВ is a section of a program that describes an object.В (A more complete definition will come later on in these notes.) Small programs often consist This is not required by Java, but makes the program easier to understand. Lines are indented to show the logical structure of the program. On allВ computers, upper and lower case inside a Java program are important.ДЄ programming language whereВ upper and lower case make a difference is called case sensitive.В Java is case sensitive. (So if the file is named hello.javaВ withДЄ small hВ it will not work). The file must be named Hello.javaВ to match the name of the class, HelloВ On most computer systems, the upper and lower case characters of the file name are important. Public static void main ( String args )ДЄbove is the source program (source file) from chapter 5 The program types the characters Hello World!В on the monitor. a file created by a Java compiler that contains machine language for the Java virtual machine.a text file created by a programmer that contains a Java program.

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