Computer Science I: Java

What are the basic components of a computer system?

Hardware, software, programs, and operating systems.

How is Java related to the World Wide Web?

Java was used for developing web applications and applets that run in web browsers.

What does JDK stand for?

Java Development Kit; it includes tools for developing Java applications.

What is an IDE?

Integrated Development Environment; a software application that provides comprehensive facilities to programmers for software development.

How do you display output on the console in Java?

Using System.out.println().

What is the basic syntax of a Java program?

A Java program consists of classes, methods, and statements, with a main method as the entry point.

How do you compile and run a Java program?

Use javac to compile and java to run the program.

What is camelCase?

A naming convention where the first letter of each word is capitalized except for the first word (e.g., myVariableName).

What is a syntax error in Java?

A syntax error occurs when the code violates Java's grammatical rules, preventing the program from compiling.

How do you perform simple computations in Java?

Using arithmetic operators like +, -, *, /, and %.

How do you obtain input from the console in Java?

Using the Scanner class.

What are identifiers in Java?

Names used to identify variables, constants, methods, and classes.

How do you store data in variables?

By declaring a variable and assigning a value to it.

What is an assignment statement?

A statement that assigns a value to a variable (e.g., x = 5;).

What are constants in Java?

Variables whose values cannot be changed once assigned, typically declared using the final keyword.

What are Java numeric primitive data types?

byte, short, int, long, float, and double.

How do you read a numeric value from the keyboard?

Using the Scanner class methods like nextInt(), nextDouble(), etc.

What operators are used for arithmetic operations in Java?

+, -, *, /, and %.

How do you perform exponentiation in Java?

Using Math.pow(a, b).

What are literals in Java?

Fixed values that are directly written in the code, such as integer literals, floating-point literals, and string literals.

How do you obtain the current system time in milliseconds?

Using System.currentTimeMillis().

What are augmented assignment operators?

Operators that combine an arithmetic operation with assignment (e.g., +=, -=, *=, /=).

What are relational operators?

Operators used to compare two values (e.g., ==, !=,

What is the difference between postincrement and preincrement?

Postincrement (i++) increments after the current value is used; preincrement (++i) increments before the current value is used.

How do you cast one data type to another in Java?

By using the cast operator (e.g., (int)variable).

How do you declare boolean variables?

By using the boolean keyword (e.g., boolean isTrue = true;).

What is a one-way if statement?

A conditional statement that executes a block of code if the condition is true.

What is a two-way if-else statement?

A conditional statement that executes one block of code if the condition is true and another block if it is false.

What is a nested if statement?

An if statement inside another if statement.

What is a switch statement?

A control statement that allows multi-way branching based on the value of a variable.

How do you generate random numbers in Java?

Using the Math.random() method.

What are logical operators?

Operators used to combine multiple boolean expressions (e.g., &&, ||, !).

What is the purpose of the break statement?

To exit a loop or switch statement prematurely.

What is a method in Java?

A block of code that performs a specific task and can be called when needed.

What is the difference between a method call and a method definition?

A method call executes the method, while a method definition specifies what the method does.

What is the difference between an argument and a parameter?

A parameter is a variable in the method definition, while an argument is the actual value passed to the method.

What are access modifiers in Java?

Keywords that set the accessibility of classes, methods, and variables (e.g., private, public, protected).

What is the method signature?

The combination of the method's name and its parameter list.

What is method overloading?

Defining multiple methods with the same name but different parameter lists.

What is the difference between a void method and a return method?

A void method does not return a value, while a return method returns a value of a specified type.

What is variable scope?

The context in which a variable is accessible, determined by where it is declared.

What is an API in Java?

An API (Application Programming Interface) is a set of classes and interfaces that provide functionality for Java applications.

How do you write a simple Java program?

Define a class, include a main method, and write statements inside it.

What are Java style conventions?

Rules for naming variables, classes, and methods, using camelCase and proper indentation.

What is the difference between style and syntax in Java?

Syntax refers to the rules of the language, while style involves best practices for readability and maintainability.

What is scientific notation in Java?

A way to represent very large or very small numbers using E or e (e.g., 1.23E4 for 12300).

What is operator precedence?

The order in which operators are evaluated in an expression.

What is operator associativity?

The direction in which an expression is evaluated when operators have the same precedence (left-to-right or right-to-left).

How do you represent characters in Java?

Using the char data type, which holds a single character.

What is ASCII?

A character encoding standard that represents characters using numbers.

What is Unicode?

A character encoding system that includes ASCII and additional characters for multiple languages.

What are escape sequences in Java?

Consists of a backslash (\) followed by a character or a combination of digits

How do you convert a numeric value to a character?

By casting an int to char (e.g., (char)65 gives A).

How do you compare characters in Java?

Using relational operators (==, !=,

What is an object in Java?

An instance of a class that contains data (fields) and methods.

What is an instance method?

A method that belongs to an instance of a class and requires an object to be invoked.

How do you represent strings in Java?

Using the String class.

How do you concatenate strings in Java?

Using the + operator or concat() method.

How do you convert a string to uppercase or lowercase?

Using toUpperCase() and toLowerCase() methods.

How do you remove leading and trailing spaces from a string?

Using the trim() method.

How do you read a string from the console?

Using Scanner and nextLine().

How do you compare strings in Java?

Using .equals() for content comparison and compareTo() for lexicographical comparison.

How do you find a character or substring in a string?

Using indexOf().

How do you obtain a substring from a string?

Using substring(startIndex, endIndex).

How do you format output in Java?

Using System.out.printf()

What is a while loop?

A loop that runs as long as its condition evaluates to true.

What is a do-while loop?

A loop that executes at least once before checking the condition.

What is a for loop?

A loop that consists of an initialization, condition, and update statement.

What is a nested loop?

A loop inside another loop.

What is a loop control variable?

A variable that controls the number of loop iterations.

What is a sentinel value?

A special value that signals the end of input.

What is a flag variable?

A boolean variable used to control the flow of a loop.

How do you exit a loop prematurely?

Using the break statement.

How do you skip an iteration of a loop?

Using the continue statement.

How can you remove a break statement from a loop?

By using a flag variable to control the loop's termination.

How do you pass data to a method?

By using parameters in the method definition.

What is method overloading?

Defining multiple methods with the same name but different parameter lists.

What is the private access modifier in Java?

The private modifier restricts access to the member within the same class only. It cannot be accessed from outside the class.

What is the public access modifier in Java?

The public access modifier in Java will allow you access to the data anywhere in the program.

What is the protected access modifier in Java?

The protected modifier allows a class member to be accessed within the same package and by subclasses, even if they are in different packages.

Draw an If Statement Flowchart

Done!

Draw an If Else Statement Flowchart

Done!

Draw a Switch Statement Diagram

Done!

Draw a While Statement Flowchart

Done!

Draw a Do-While Statement Flowchart

Done!

What is a runtime error in Java?

A runtime error occurs while running if the environment detects an operation that is impossible to carry out.

What is a logic error in Java?

A logic error occurs when a program does not perform the way it was intended to.

What is the difference between postdecrement and predecrement in Java?

Postdecrement (i--): The current value of i is used first, then i is decremented.
Predecrement (--i): i is decremented first, then the updated value is used.