Java Program Structure and Guidelines
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Java Program Structure and Guidelines

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What must be avoided when naming identifiers in Java?

  • Using underscores
  • Using alphabetic characters
  • Using mixed cases for multi-word identifiers
  • Starting with a number (correct)

    • What is a defining feature of JavaDoc comments?

  • They start with a forward slash and two asterisks (/**) (correct)
  • They always contain HTML format
  • They are used for variable declarations
  • They begin with two forward slashes (//)

    • Which of the following correctly describes an end-of-line comment?

  • Only the text following the slashes is ignored (correct)
  • It can be used to document entire classes
  • It must be in a separate line from code
  • It can only be used at the beginning of the line

    • Which guideline is recommended for naming identifiers in Java?

    <p>Use clear and context-relevant names</p> Signup and view all the answers

    What is a significant restriction when naming identifiers?

    <p>Identifiers cannot include spaces</p> Signup and view all the answers

    Which character sequence signifies the start of a block comment in Java?

    <p>/*</p> Signup and view all the answers

    What is a suggested practice for naming multi-word identifiers?

    <p>Capitalize the first letter of each word or use underscores</p> Signup and view all the answers

    Which statement about Java keywords is true?

    <p>Keywords are reserved words and cannot be used as identifiers</p> Signup and view all the answers

    What is a necessary requirement for Java program files?

    <p>The file must have the same name as the public class.</p> Signup and view all the answers

    What do curly braces denote in a Java program?

    <p>They form a block that groups statements together.</p> Signup and view all the answers

    What does a Java statement require at the end?

    <p>A semicolon.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of comments in Java?

    <p>Comments are necessary for the program to run.</p> Signup and view all the answers

    What is the purpose of indentation in Java coding?

    <p>To improve readability.</p> Signup and view all the answers

    What is the role of the args variable in a Java program?

    <p>It can be renamed according to Java naming rules.</p> Signup and view all the answers

    Which of the following describes a block comment in Java?

    <p>Starts with /* and ends with */.</p> Signup and view all the answers

    Which statement about Java statements is correct?

    <p>They can be grouped together in a block.</p> Signup and view all the answers

    Which method is used to indicate a long (64-bit) integer in Java?

    <p>By appending an uppercase or lowercase L at the end</p> Signup and view all the answers

    What is the appropriate way to declare a float literal in Java?

    <p>float value = 5.5F;</p> Signup and view all the answers

    Which of the following options correctly specifies an octal literal?

    <p>045</p> Signup and view all the answers

    What are valid values for a Boolean literal in Java?

    <p>true and false</p> Signup and view all the answers

    How are string literals represented in Java?

    <p>Enclosed in double quotation marks</p> Signup and view all the answers

    Which of the following represents a valid character literal?

    <p>'a'</p> Signup and view all the answers

    Which statement about hexadecimal literals in Java is correct?

    <p>They are denoted by '0x' prefix</p> Signup and view all the answers

    What is a common mistake when declaring a float literal?

    <p>Forgetting the 'F' suffix</p> Signup and view all the answers

    Which of the following is NOT a primitive data type in Java?

    <p>String</p> Signup and view all the answers

    What is the initial value of a Boolean variable in Java?

    <p>false</p> Signup and view all the answers

    How many characters can the char data type represent in Java?

    <p>65,536</p> Signup and view all the answers

    Which escape sequence correctly represents the trademark symbol (™) in Java?

    <p>\u2122</p> Signup and view all the answers

    Which of the following statements about the char data type is false?

    <p>Char literals must be enclosed in double quotes.</p> Signup and view all the answers

    Which statement correctly describes the integer data types in Java?

    <p>They allow the representation of negative values.</p> Signup and view all the answers

    Which sequence must begin with the characters '\u' to represent a Unicode character?

    <p>Hexadecimal escape sequence</p> Signup and view all the answers

    Which of the following is a characteristic of the Boolean data type in Java?

    <p>It is one bit wide.</p> Signup and view all the answers

    What type should be used to represent the number of inhabitants of the planet?

    <p>long</p> Signup and view all the answers

    What is a key difference between Java and C regarding integer types?

    <p>Java provides the same integer type ranges on all machines.</p> Signup and view all the answers

    Why is the double type usually preferred over float in applications?

    <p>Double offers greater precision than float.</p> Signup and view all the answers

    Which of the following prefixes indicates a hexadecimal number in Java?

    <p>0x</p> Signup and view all the answers

    What suffix is used to denote a float type in Java?

    <p>F</p> Signup and view all the answers

    In what situations is it advisable to use the float type instead of double?

    <p>When performance and speed are critical.</p> Signup and view all the answers

    Which of the following statements is false regarding floating-point representations in Java?

    <p>Float integers cannot exceed 3.402.</p> Signup and view all the answers

    What must every variable in Java have?

    <p>A specific data type and a name.</p> Signup and view all the answers

    Study Notes

    Java Program Structure

    • Program name: The name of the Java program is an identifier that should be the same as the filename.
    • Curly braces: Every Java program requires at least two pairs of curly braces: one surrounding the entire program and another surrounding the main method.
    • args variable: This is a placeholder for the command-line arguments that the program can receive.

    Java Coding Guidelines

    • Filename: The filename of a Java program must match the public class name and end with .java.
    • Comments: Use comments for documentation and readability. They are ignored by the compiler.
    • White spaces: White spaces (like spaces and tabs) are ignored by the compiler.
    • Indentation: Indentation is for readability and helps organize the code.

    Java Statements

    • Statement: A statement is one or more lines of code terminated by a semicolon (;). It represents an action to be performed during the program's execution.
    • Block: A block is a group of statements enclosed within curly braces ({}). Blocks act as single units and replace statements within a program's structure.
    • Comments: Comments are used for documentation and are ignored by the compiler.
      • Block comment: Begins with /* and ends with */. Used for multi-line descriptions.
      • Line comment: Starts with // and continues until the end of the line. Used for single-line comments.
      • JavaDoc comment: Starts with /** and ends with */. Used for documenting classes, attributes, and methods.

    Identifiers

    • Definition: Identifiers are names used by programmers to identify elements like classes, methods, and variables.
    • Naming rules:
      • Must start with a letter, underscore _, or dollar sign $.
      • Can contain letters, numbers, underscores, and dollar signs after the first character.
      • Cannot be a Java keyword.
    • Guidelines:
      • Choose names that describe the purpose of the element.
      • Use lowercase for method and variable names, uppercase for class names.
      • Separate words in multi-word identifiers with underscores or by capitalizing the first letter of each word.

    Java Keywords

    • Definition: Keywords are reserved words that have specific meanings in the Java language. They cannot be used as identifiers.
    • Examples: public, class, static, void, main, String, System, out, println, int, for, while, if, else

    Java Literals

    • Definition: Literals are values that are directly represented in the code.
    • Integer literals:
      • Decimal: Start with a non-zero digit and don't contain a decimal point.
      • Octal: Start with a leading 0.
      • Hexadecimal: Start with 0x.
    • Floating-point literals: End with F or f to indicate float type.
    • Boolean literals: true or false.
    • String literals: Enclosed in double quotes ("). Can contain escape sequences.
    • Character literals: Enclosed in single quotes ('). Can contain escape sequences.

    Data Types

    • Simple types: Built-in, primitive data types.
    • Composite types: Created by programmers using simple types, arrays, classes, and interfaces.
    • Primitive data types:
      • boolean: Stores true or false values.
      • char: Stores single Unicode characters.
      • byte: Stores integers from -128 to 127.
      • short: Stores integers from -32,768 to 32,767.
      • int: Stores integers from -2,147,483,648 to 2,147,483,647 (most widely used).
      • long: Stores integers from -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807.
      • float: Stores single-precision floating-point numbers (7 significant digits).
      • double: Stores double-precision floating-point numbers (15-16 significant digits).

    Variables

    • Definition: Variables are named locations in memory that store data.
    • Components: Each variable has a data type and a name. The data type determines the kind of data the variable can hold.

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    Related Documents

    Module 04 - Java Syntax and Grammar PDF

    Description

    This quiz covers the fundamental structure of a Java program, including naming conventions, the use of curly braces, and the args variable. Additionally, it addresses coding guidelines such as comments, whitespace, indentation, and statements. Test your understanding of these essential Java concepts.

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