All Flashcards
What are the differences between arrays and ArrayLists?
Arrays: Fixed size, primitive and object types, length property. ArrayLists: Dynamic size, object types only, methods like add(), remove(), size().
What are the differences between == and .equals() for Strings?
==: Compares object references. .equals(): Compares the content of the strings.
What are the differences between for and while loops?
for: Used when the number of iterations is known. while: Used when the number of iterations is unknown, and depends on a condition.
What are the differences between method overloading and method overriding?
Overloading: Multiple methods with the same name but different parameters in the same class. Overriding: A subclass providing a different implementation for a method already defined in its superclass.
What are the differences between x++ and ++x?
x++: Post-increment, returns the original value then increments. ++x: Pre-increment, increments then returns the new value.
What is the value of x after: int x = 5; x += 3;?
8
What is the value of y after: int y = 10; y /= 2;?
5
What is the output of: String s = "Hello"; System.out.println(s.substring(1, 4));?
ell
What is the output of: int[] arr = {1, 2, 3}; System.out.println(arr[1]);?
2
What is the output of: ArrayList<String> list = new ArrayList<>(); list.add("A"); System.out.println(list.get(0));?
A
What is the output of: int[][] matrix = {{1, 2}, {3, 4}}; System.out.println(matrix[1][0]);?
3
What is the output: int x = 5; if (x > 3) System.out.print("A"); else System.out.print("B");?
A
What is the output: for(int i = 0; i < 3; i++) System.out.print(i);?
012
What is wrong with: String s = "Hello"; s[0] = 'J';?
Strings are immutable; you cannot change a character at a specific index directly.
What is the output: int x = 5; System.out.println(x++); System.out.println(x);?
5 6
What is the output: int x = 5; System.out.println(++x); System.out.println(x);?
6 6
What is the output: String str1 = "hello"; String str2 = new String("hello"); System.out.println(str1 == str2);?
false
What is the output: String str1 = "hello"; String str2 = new String("hello"); System.out.println(str1.equals(str2));?
true
How are arrays applied in real-world scenarios?
Storing lists of data, such as student names, product prices, or sensor readings.
How are ArrayLists applied in real-world scenarios?
Managing a dynamic list of items, such as a shopping cart or a playlist.
How are 2D arrays applied in real-world scenarios?
Representing tables of data, such as spreadsheets, game boards, or image pixels.
How is inheritance applied in real-world scenarios?
Creating a hierarchy of classes, such as different types of vehicles inheriting from a base Vehicle class.
How is recursion applied in real-world scenarios?
Solving problems that can be broken down into smaller, self-similar subproblems, such as searching a file system or parsing a complex data structure.
How are if statements applied in real-world scenarios?
Controlling program flow based on conditions, such as validating user input or determining which action to take based on the current state.
How are for loops applied in real-world scenarios?
Iterating through a collection of data, such as processing each item in a list or performing an action a specific number of times.
How are while loops applied in real-world scenarios?
Repeating an action until a certain condition is met, such as continuously reading data from a sensor until a specific value is reached.