Weeks 1-4; Elementary, Conditionals, Loops Flashcards
What are the two types of Java programs?
Applications: Standalone programs. Applets: Require a Java-enabled browser to run.
What are the three looping structures in Java?
while (pre-test loop), do-while (post-test loop), for (pre-test loop with control).
What is the difference between while and do-while?
while tests the condition first; do-while executes at least once before testing.
How do you structure a basic if statement?
An if statement checks a condition, and if it is true, executes a block of statements.
How do you structure a for loop?
A for loop combines initialization, condition check, and update in one line.
What is a flag in Java?
A boolean variable that monitors a condition in a program, e.g., boolean highScore.
How do you generate a random number in Java?
Use the Random class and methods like nextInt() or nextDouble() to generate numbers.
How are comments written in Java?
Single-line: // comment; Multi-line: /* comment /; Javadoc: /* comment */.
What is the purpose of the break statement?
Terminates a loop prematurely.
What is the purpose of the continue statement?
Skips the current iteration and moves to the next iteration.
How are strings compared in Java?
Use .equals(), .equalsIgnoreCase() for equality; .compareTo() for lexicographical order.
What is the syntax for a switch statement?
A switch statement evaluates a value and matches it against multiple cases for execution.
How do you create a constant in Java?
Use the final keyword to declare a constant value that cannot change.
How is input validated using a loop?
Use a while loop to repeatedly prompt the user until valid input is entered.
What is the purpose of curly braces {} in loops?
To group multiple statements into a block to execute together.
What are escape sequences in Java?
Examples: \n (newline), \t (tab), \ (backslash), “ (double quote).
What is the purpose of the Scanner class?
To read input from the user using methods like nextInt() or nextLine().
What are the three parts of a for loop?
Initialization: Sets the control variable. Condition: Tests the loop variable. Update: Modifies the control variable.
What is a sentinel value?
A special value indicating the end of input, e.g., -1 in a list of positive numbers.
What is the ternary operator?
A compact form of if-else: result = (condition) ? value1 : value2.
What is the Random class used for?
To generate random numbers using methods like nextInt() and nextDouble().
How is an infinite loop caused?
Forgetting to update the control variable or setting a condition that is always true.
What is a nested loop?
A loop inside another loop where the inner loop completes all iterations for each outer loop iteration.
What are Java reserved keywords?
Examples: abstract, class, void, static, if, else, while, etc.
How are local variables scoped?
Scope begins at declaration and ends at the method’s closing brace.
How do you concatenate strings in Java?
Use the + operator, e.g., “Hello “ + “World”.
What are arithmetic operators in Java?
+, -, *, /, %
What is integer division?
Division with two integers truncates the decimal part, e.g., 5 / 2 = 2.
How does System.out.printf work?
Used for formatted output, allowing control over display of variables and text.
What are relational operators?
> , <, >=, <=, ==, !=
How do logical operators work?
&&: AND, ||: OR, !: NOT
How is a string’s length found?
Use the .length() method to retrieve the length of a string.
What is a bytecode file?
A compiled Java file with .class extension, interpreted by the JVM.
What are escape sequences for characters?
\n (newline), \t (tab), “ (quote), \ (backslash).
What is Object-Oriented Programming (OOP)?
A programming paradigm based on objects that encapsulate data and behavior.
What are the four pillars of OOP?
Encapsulation, Inheritance, Polymorphism, and Abstraction.
What is encapsulation in Java?
Bundling data (fields) and methods that operate on the data into a single unit (class).
How is inheritance implemented in Java?
Using the extends keyword to create a subclass from a parent class.
What is polymorphism in Java?
The ability of objects to take on multiple forms, such as method overriding or overloading.
What is abstraction in Java?
Hiding complex implementation details and showing only essential features.
What is a class in Java?
A blueprint for creating objects that encapsulate data and methods.
What is an object in Java?
An instance of a class containing specific data and behavior.
How do you create an object in Java?
Use the new keyword: ClassName obj = new ClassName();
What are constructors in Java?
Special methods used to initialize new objects.
What is method overloading?
Defining multiple methods with the same name but different parameter lists.
What is method overriding?
Redefining a method in a subclass that already exists in the parent class.
What is the difference between this and super?
this refers to the current object; super refers to the parent class.
What are interfaces in Java?
A reference type that defines abstract methods a class must implement.
How do abstract classes differ from interfaces?
Abstract classes can have implemented methods; interfaces cannot (prior to Java 8).
What is the static keyword used for?
To declare class-level variables or methods shared among all objects of a class.
What is a control statement in Java?
A statement that determines the flow of execution, e.g., if, for, while, switch.
What is the difference between pre-test and post-test loops?
Pre-test loops (while, for) check the condition before executing; post-test loops (do-while) execute at least once.
How is the order of precedence determined in Java?
Operators are evaluated in a specific order: ! > arithmetic > relational > logical.
What are the types of errors in Java?
Syntax errors, runtime errors, and logical errors.
What is short-circuit evaluation in logical operators?
Logical AND (&&) stops if the first condition is false; logical OR (||) stops if the first condition is true.
What are flowcharts used for in programming?
To visually represent the flow of control in algorithms or program logic.
