Podcast
Questions and Answers
What must any program in Java have?
at least one class
Java is case-sensitive in its syntax.
True
What is the entry point for executing a Java program?
main method
What file extension do Java files have?
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What does System.out.println() do?
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What does the escape sequence \n represent?
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Match the following formatting specifiers with their descriptions:
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What do you put at the end of a statement in Java?
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Write a single line comment in Java.
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What is the syntax for the main method in Java?
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Study Notes
Principles of Programming
- Any program in Java must have at least one class.
- Classes consist of methods and data items.
- Classes must have a beginning and an end, marked by curly braces "{ }".
- Statements in Java must end with a semicolon (;).
- Java is case-sensitive.
- Code is stored in files with the .java extension.
Output / Print
- System.out.print(): Prints a string to the console without a newline character.
- System.out.println(): Prints a string to the console followed by a newline character.
- System.out.printf(): Allows for formatted printing to the console.
Escape Sequences
- \n: Newline
- \t: Tab
- \r: Carriage return
- \: Prints a backslash character
- \”: Prints a double-quote character
Formatting With printf()
- %c: Formats characters
- %d: Formats decimal (integer) numbers (base 10)
- %e: Formats exponential floating-point numbers
- %f: Formats floating-point numbers
- %o: Formats octal numbers (base 8)
- %s: Formats a string of characters
- %x: Formats numbers in hexadecimal (base 16)
- %n: Inserts a newline character
Formatting a String
- System.out.printf("%s%n", "hello world!"); Prints a string followed by a newline character.
- System.out.printf("'%S' %n", "hello world!"); Prints a string enclosed in single quotes followed by a newline character.
Formatting Numbers
- System.out.printf("it is an integer: %d%n", 10000); Formats an integer.
- System.out.printf("%f%n", 3.1423); Formats a floating-point number with default precision.
- System.out.printf("%3.2f'%n", 3.1423); Formats a floating-point number with a specific precision (3 digits total, 2 after the decimal point).
Comments in Java
- Single-line comments: Start with '//' and extend to the end of the line.
- Multi-line comments: Start with '/' and end with '/'.
Flow of Control
- Linear Execution: Statements are executed in order unless otherwise specified.
- Flow Control Statements: Allow for decisions in code execution, such as conditional execution or loops.
If...Else Statement
- Allows for conditional execution based on a Boolean expression.
Ternary Operator
- Provides a concise syntax for conditional expressions.
Switch Statement
- Allows for branching execution based on a variable's value.
Shorthand Operators
- Provide a concise syntax for common mathematical operations.
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Description
Test your understanding of the fundamental principles of Java programming, including class structures, methods, and data items. This quiz also covers output techniques and the use of escape sequences, alongside formatted printing with printf().
