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Questions and Answers
Which of the following types of languages best describes Java?
Which of the following types of languages best describes Java?
In what kind of language are the original source files distributed to the target computer?
In what kind of language are the original source files distributed to the target computer?
Which language family has been around since the 1970s and gained object-oriented concepts in a later decade?
Which language family has been around since the 1970s and gained object-oriented concepts in a later decade?
Which pair of companies are the original and current owners of the Java language?
Which pair of companies are the original and current owners of the Java language?
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What important JRE component lets Java programs run on any operating system without recompiling?
What important JRE component lets Java programs run on any operating system without recompiling?
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The Java compiler will turn files from which input format to which output format?
The Java compiler will turn files from which input format to which output format?
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What part of the Java platform will programmers install to get tools that compile Java source code?
What part of the Java platform will programmers install to get tools that compile Java source code?
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What key feature distinguishes Java from earlier, high-level compiled languages like C++?
What key feature distinguishes Java from earlier, high-level compiled languages like C++?
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What is the name of the command we can use to display a line of text to the output console?
What is the name of the command we can use to display a line of text to the output console?
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Which of the following keywords does Java use to describe a group of statements that work together to perform a task?
Which of the following keywords does Java use to describe a group of statements that work together to perform a task?
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Which of the following contains a properly formatted main() method declaration?
Which of the following contains a properly formatted main() method declaration?
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Which important pair of symbols are used to mark the start and end of classes, methods, and other blocks of code?
Which important pair of symbols are used to mark the start and end of classes, methods, and other blocks of code?
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Which symbol is used to mark the end of a program statement?
Which symbol is used to mark the end of a program statement?
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Why is using white space important in your Java source code?
Why is using white space important in your Java source code?
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How do you start and end a multi-line comment?
How do you start and end a multi-line comment?
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What is the purpose of indenting some statements to the right in Java source files?
What is the purpose of indenting some statements to the right in Java source files?
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Which area would you visit within Oracle's online Java documents to get reference information on any class in the JCL?
Which area would you visit within Oracle's online Java documents to get reference information on any class in the JCL?
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Which area would you visit to get step-by-step guidance on a variety of Java topics?
Which area would you visit to get step-by-step guidance on a variety of Java topics?
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Which of the following data types is best suited to hold the number of goals scored by a soccer team?
Which of the following data types is best suited to hold the number of goals scored by a soccer team?
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Which of the following data types is best suited to hold the elapsed time in a race, including two digits to the right of the decimal point?
Which of the following data types is best suited to hold the elapsed time in a race, including two digits to the right of the decimal point?
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Which data type would you choose to hold the answer to a true / false question?
Which data type would you choose to hold the answer to a true / false question?
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Which data type will hold a single character like 'X'?
Which data type will hold a single character like 'X'?
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What limits a numeric data type's precision and range?
What limits a numeric data type's precision and range?
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What is the best naming style to use for a variable that contains a count of the number of frogs in a pond?
What is the best naming style to use for a variable that contains a count of the number of frogs in a pond?
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What two things do you need to declare (but not initialize) a new variable in your code?
What two things do you need to declare (but not initialize) a new variable in your code?
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Which of the following variable names is invalid?
Which of the following variable names is invalid?
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Which of the following statements will successfully assign a true value to the boolean variable 'isReady'?
Which of the following statements will successfully assign a true value to the boolean variable 'isReady'?
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Study Notes
Java Language Characteristics
- Java is classified as a high-level language, designed for readability and ease of use.
- It differs from machine language, which consists of binary instructions directly understood by the computer's CPU.
- Original source files in interpreted or scripted languages are typically run without prior compilation.
Java Language Family and History
- The C/C++ language family emerged in the 1970s and later adapted object-oriented programming concepts.
- The original owner of Java was Sun Microsystems, which later became Oracle.
Java Runtime and Development
- The Java Virtual Machine (JVM) enables Java programs to run on any operating system without recompilation.
- Java source code is compiled from
.java
files to.class
files by the Java compiler. - The Java Development Kit (JDK) provides essential tools for compiling Java code and creating executable distributions.
Source Code Structure
- A key feature of Java is cross-platform compatibility, where compiled programs run on any computer with a JVM.
- The command
System.out.println()
outputs text to the console. - The keyword
class
denotes a group of statements that work together in object-oriented programming.
Main Method and Code Blocks
- The correct declaration for the main method is
public static void main(String[] args)
. - Code blocks, including classes and methods, are defined by opening and closing curly braces
{}
. - A statement in Java ends with a semicolon
;
.
Code Readability and Commenting
- White space in Java source code enhances readability for developers.
- Multi-line comments start with
/*
and end with*/
. - Indentation visually organizes code, indicating which lines belong to the same block.
Java Documentation Resources
- API Documentation provides reference information for any class in the Java Class Library (JCL).
- Java Tutorials offer step-by-step guidance on various programming topics.
Data Types in Java
- The
int
data type is ideal for counting discrete values, such as goals scored in a soccer game. - The
float
data type is well-suited for measuring elapsed time, allowing for decimal precision. - The
boolean
data type is used to represent true or false values, whilechar
holds single characters.
Variable Declaration and Naming
- Numeric data types' precision and range are limited by the number of bytes allocated in memory.
- When declaring a variable, both the data type and variable name are required but initialization is optional.
- Variable names must not contain spaces, making "race time" an invalid name.
Variable Assignment and Operations
- The statement
isReady = true;
assigns a true value to an already declared boolean variable. - A series of assignments such as
int result = 42; result = 43; result = 44;
results in the variableresult
storing the last assigned value, which is 44.
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Description
Test your knowledge of programming languages with this engaging quiz! Each question explores different types of programming languages, including high-level and machine languages. Perfect for beginners and enthusiasts alike.