All Flashcards
What is the output of the following code?
java
ArrayList<Integer> nums = new ArrayList<>(Arrays.asList(1, 2, 3));
for (int i = 0; i < nums.size(); i++) {
System.out.print(nums.get(i) + " ");
}
1 2 3
What is the output of the following code?
java
ArrayList<String> words = new ArrayList<>(Arrays.asList("hello", "world"));
for (String word : words) {
System.out.print(word + " ");
}
hello world
Identify the error in the following code:
java
ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(1, 2, 3));
for (int i = 0; i <= numbers.size(); i++) {
System.out.println(numbers.get(i));
}
IndexOutOfBoundsException. The loop condition should be i < numbers.size().
What is the output of the following code?
java
ArrayList<Integer> list = new ArrayList<>(Arrays.asList(2, 4, 6, 8));
for (int i = 0; i < list.size(); i++) {
if (list.get(i) % 4 == 0) {
list.remove(i);
i--;
}
}
System.out.println(list);
[2, 6]
What is the output of the following code?
java
ArrayList<Integer> list = new ArrayList<>(Arrays.asList(1, 3, 5, 7));
for (int i = 0; i < list.size(); i++) {
if (list.get(i) % 2 != 0) {
list.add(i, list.get(i));
i++;
}
}
System.out.println(list);
[1, 1, 3, 3, 5, 5, 7, 7]
Identify the error in the following code:
java
ArrayList<Integer> nums = new ArrayList<>(Arrays.asList(1, 2, 3));
for (Integer num : nums) {
if (num % 2 == 0) {
nums.remove(num);
}
}
ConcurrentModificationException. Cannot modify the ArrayList while using an enhanced for loop.
What is the output of the following code?
java
ArrayList<String> names = new ArrayList<>(Arrays.asList("Alice", "Bob", "Charlie"));
for (String name : names) {
name = "David";
}
System.out.println(names);
[Alice, Bob, Charlie]
What is the output of the following code?
java
ArrayList<Integer> numbers = new ArrayList<>(Arrays.asList(10, 20, 30));
for (int i = 0; i < numbers.size(); i++) {
numbers.set(i, numbers.get(i) / 2);
}
System.out.println(numbers);
[5, 10, 15]
What is the output of the following code?
java
ArrayList<Integer> values = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5));
values.removeIf(n -> (n % 2 == 0));
System.out.println(values);
[1, 3, 5]
What is the output of the following code?
java
ArrayList<String> colors = new ArrayList<>(Arrays.asList("red", "green", "blue"));
colors.forEach(color -> System.out.print(color.toUpperCase() + " "));
RED GREEN BLUE
What are the differences between using a regular for loop and an enhanced for loop to traverse an ArrayList?
Regular for loop: Requires manual index management, allows modifications to the ArrayList during traversal. Enhanced for loop: Simpler syntax, does not allow modifications to the ArrayList during traversal.
What are the differences between modifying an ArrayList using set() within a for loop vs. modifying the enhanced for loop variable?
set(): Changes the actual element in the ArrayList. Enhanced for loop variable modification: Only changes the loop variable, not the ArrayList element (pass-by-value).
What are the differences between handling IndexOutOfBoundsException and ConcurrentModificationException?
IndexOutOfBoundsException: Occurs due to invalid index access. ConcurrentModificationException: Occurs due to structural modification during enhanced for loop traversal.
Compare the performance implications of adding elements at the end versus the beginning of an ArrayList.
Adding at the end: Generally faster, O(1) amortized time. Adding at the beginning: Slower, O(n) time due to element shifting.
Compare the use of removeIf() with a regular for loop for removing elements from an ArrayList based on a condition.
removeIf(): More concise, uses lambda expressions. Regular for loop: More control over the removal process and index management.
What are the differences between ArrayList and a standard Java array when traversing and modifying elements?
ArrayList: Dynamic size, uses get() and set() methods. Array: Fixed size, uses bracket notation for access and modification.
Compare the efficiency of searching for an element in an ArrayList using a loop versus using the contains() method.
Loop: Requires manual iteration, O(n) time complexity. contains(): Uses built-in optimized search, potentially faster in some implementations.
What are the differences between using a while loop and a for loop to traverse an ArrayList?
While loop: Requires manual initialization and increment of the index. For loop: More concise and manages index automatically.
Compare the readability and maintainability of using streams and lambda expressions versus traditional loops for processing ArrayList elements.
Streams and lambdas: More concise and declarative, can improve readability. Traditional loops: More verbose, but can be easier to understand for complex logic.
What are the differences between using Iterator and enhanced for loop for traversing an ArrayList?
Iterator: Allows removing elements during traversal using iterator.remove(). Enhanced for loop: More concise but does not allow removing elements.
What is an ArrayList?
A resizable array implementation of the List interface.
What is IndexOutOfBoundsException?
An exception thrown when trying to access an invalid index in an ArrayList.
What is ConcurrentModificationException?
An exception thrown when an ArrayList is structurally modified while being traversed with an enhanced for loop.
What does 'pass-by-value' mean?
A method of passing arguments to a function where a copy of the variable's value is passed, not the original variable itself.
What is the purpose of the get() method in ArrayList?
It retrieves the element at a specific index in the ArrayList.
What is the purpose of the size() method in ArrayList?
It returns the number of elements currently in the ArrayList.
What is the purpose of the remove(i) method in ArrayList?
It removes the element at the specified index i from the ArrayList.
What is the purpose of the add(i, element) method in ArrayList?
It inserts the specified element at the specified position i in the ArrayList.
What is traversing?
Visiting each element in a data structure, such as an ArrayList, in a specific order.
What is the purpose of the set() method in ArrayList?
Replaces the element at the specified position in this list with the specified element.