Good Programming Practice 2.2 Use lines and space characters to enhance program readability. Line 4 public class Welcome1 begins a declaration for class Every program in Java consists of at least one Welcome1. class declaration that is defined by youthe programmer. These are known as or The introduces a class declaration in classes user-defined classes. class keyword Java and is immediately followed by the class name (Welcome1). Keywords (sometimes called reserved words) are reserved for use by Java (we discuss the various keywords throughout the text) and are always spelled with all lowercase letters. By convention, all class names in Java begin with a capital letter and capitalize the first letter of each word they include (e.g., A Java class name is an identifiera series of SampleClassName). characters consisting of letters, digits, underscores (_) and dollar signs ($) that does not begin with a digit and does not contain spaces. Some valid identifiers are Welcome1, $value, and The name is not a valid identifier because it _value, m_inputField1 button7. 7button begins with a digit, and the name is not a valid identifier because it contains a input field space. Normally, an identifier that does not begin with a capital letter is not the name of a Java class. Java is case sensitive that is, uppercase and lowercase letters are distinct, so and are a1 A1 different (but both valid) identifiers. Good Programming Practice 2.3 By convention, always begin a class name's identifier with a capital letter and start each subsequent word in the identifier with a capital letter. Java programmers know that such identifiers normally represent Java classes, so naming your classes in this manner makes your programs more readable. Common Programming Error 2.2 Java is case sensitive. Not using the proper uppercase and lowercase letters for an identifier normally causes a compilation error. class we define begins with the keyword. For now, we will simply require this public keyword. When you save your class declaration in a file, the file name must be the class public name followed by the ".java" file-name extension. For our application, the file name is Welcome1.java. Common Programming 2.3
Good Programming Practice 2.2 Use lines and space characters to enhance program readability. Line 4 public class Welcome1 begins a declaration for class Welcome1. Every program in Java consists of at least one class declaration that is defined by youthe programmer. These are known as classes or user-defined classes. The class keyword introduces a class declaration in Java and is immediately followed by the class name (Welcome1). Keywords (sometimes called reserved words) are reserved for use by Java (we discuss the various keywords throughout the text) and are always spelled with all lowercase letters. By convention, all class names in Java begin with a capital letter and capitalize the first letter of each word they include (e.g., SampleClassName). A Java class name is an identifiera series of characters consisting of letters, digits, underscores (_) and dollar signs ($) that does not begin with a digit and does not contain spaces. Some valid identifiers are Welcome1, $value, _value, m_inputField1 and button7. The name 7button is not a valid identifier because it begins with a digit, and the name input field is not a valid identifier because it contains a space. Normally, an identifier that does not begin with a capital letter is not the name of a Java class. Java is case sensitive that is, uppercase and lowercase letters are distinct, so a1 and A1 are different (but both valid) identifiers. Good Programming Practice 2.3 By convention, always begin a class name's identifier with a capital letter and start each subsequent word in the identifier with a capital letter. Java programmers know that such identifiers normally represent Java classes, so naming your classes in this manner makes your programs more readable. Common Programming Error 2.2 Java is case sensitive. Not using the proper uppercase and lowercase letters for an identifier normally causes a compilation error. class we define begins with the public keyword. For now, we will simply require this keyword. When you save your public class declaration in a file, the file name must be the class name followed by the ".java" file-name extension. For our application, the file name is Welcome1.java. Common Programming 2.3
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