Programming Basics: Loops and Arrays

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Questions and Answers

What is the primary benefit of using an ArrayList over a traditional array?

ArrayLists automatically resize. (correct)

ArrayLists require manual resizing.

ArrayLists are more memory efficient than arrays.

ArrayLists can only store integers.

Which method would you use to determine the number of elements in an ArrayList?

list.count()

list.length()

list.size() (correct)

list.getSize()

What will be the value of val after executing the code 'int val = list.get(1);' if the list contains {5, 3, 10, 4}?

3 (correct)

What happens when you execute 'list.set(2, 88);' on the list {5, 3, 10, 4}?

The list becomes {5, 3, 88, 4}. Signup and view all the answers

What is the correct way to loop over an ArrayList named list using an enhanced for loop?

for(int elem: list) {} Signup and view all the answers

What will be printed when executing `System.out.println(myList.get(0));` after adding the element 100 to the list?

100 Signup and view all the answers

What is the size of the ArrayList `numbers` after the loop that adds integers from 0 to 99?

100 Signup and view all the answers

What value will be at index 3 of the `numbers` ArrayList after adding the numbers 1 to 5 and 10 at index 3?

10 Signup and view all the answers

If an attempt is made to access an index that is out of range in an ArrayList, what will occur?

An IndexOutOfBoundsException will be thrown. Signup and view all the answers

What will happen if you try to retrieve an element from an empty ArrayList?

It will throw an IndexOutOfBoundsException. Signup and view all the answers

What value does the variable 'x' hold when accessing the third element in the second array of myNumbers?

7 Signup and view all the answers

Which of the following statements about multidimensional arrays is correct?

They can be accessed using nested loops. Signup and view all the answers

Which of the following is NOT a constructor for creating an ArrayList?

ArrayList(Object o) Signup and view all the answers

Which method is used to determine the number of elements in an ArrayList?

size() Signup and view all the answers

What is a limitation of standard arrays in Java?

They are fixed in size. Signup and view all the answers

Which class from the Java collection framework provides a dynamic array?

ArrayList Signup and view all the answers

Which of the following methods is used to remove an element from an ArrayList?

remove(int index) Signup and view all the answers

Which of the following data types cannot be directly stored in an ArrayList?

int Signup and view all the answers

What is the primary characteristic of an array in programming?

It holds a fixed number of values of a single type. Signup and view all the answers

Which of the following statements correctly describes array instantiation?

You must declare the array before instantiating it using the new keyword. Signup and view all the answers

Which of the following correctly represents the syntax for a for loop in Java?

for (initialization; condition; increment) { } Signup and view all the answers

What happens when the Boolean expression in a while loop evaluates to false?

The loop ends and control passes to the next statement. Signup and view all the answers

In Java, how do you access the first element of an array named arr?

arr[0] Signup and view all the answers

What is a potential issue if you try to access an index that is out of bounds in an array?

An ArrayIndexOutOfBoundsException will be thrown. Signup and view all the answers

What type of loop is best suited for situations where the number of iterations is known beforehand?

For loop Signup and view all the answers

Which of the following best describes the declaration of an array in Java?

int[] arr; Signup and view all the answers

What is the correct syntax for instantiating an array of integers?

int[] arr = new int; Signup and view all the answers

How can you change the second element of a String array named 'cars'?

cars[1] = 'Honda'; Signup and view all the answers

Which statement correctly loops through all elements in an array using a for-each loop?

for(int i : cars) { System.out.println(i); } Signup and view all the answers

What is required to access an element in a two-dimensional array?

One index for the array and one index for the element. Signup and view all the answers

Which of the following correctly initializes an array with specific values?

int[] arrayInt = {1, 2, 3, 4, 5}; Signup and view all the answers

In the context of arrays, what does the '.length' property signify?

The number of elements currently in the array. Signup and view all the answers

What will be the output of the following code? String[] cars = {"Volvo", "BMW", "Ford"}; System.out.print(cars[0] + ", "); System.out.print(cars[1] + ", "); System.out.println(cars[2]);

Volvo, BMW, Ford Signup and view all the answers

Which of the following statements about array elements is false?

Elements cannot be initialized after the array is created. Signup and view all the answers

Study Notes

Repetition Statements

A loop structure repeatedly executes a block of code "as long as" a tested expression is true.
If a loop's tested Boolean expression is true, a block of statements called the loop body executes. This occurs before the Boolean Expression is evaluated again.

Arrays

An array is a container object holding a fixed number of values of the same type.
Array length is set when the array is created.
Each array item (element) is accessed by a numerical index.
Arrays are declared using [ ] after the data type.
Array instantiation uses the new keyword and specifies the array's dimensions.
Array initialization assigns values to the elements. This can be done during instantiation or by assigning values by their indices.
Looping through arrays can use the for loop or the for-each loop.

Two-Dimensional Arrays

A multidimensional array holds one or more arrays.
Creating a two-dimensional array involves placing each array within its curly braces.
Accessing elements in a two-dimensional array requires specifying two indices: one for the array and one for the element within that array.
Looping through a two-dimensional array requires nested for loops, one for each dimension.

ArrayList

ArrayList is a dynamic array, meaning it can grow as needed.
It is easier to manipulate than a traditional array (e.g., removing elements).
It can only hold objects, not primitive data types.
The java.util package contains the ArrayList class.
There are several constructors for ArrayList to create an empty list, initialize it with a collection or set an initial capacity.
Common methods for ArrayList include:
- add(Object o): Adds an element to the end of the list.
- remove(int index): Removes an element at a specific index.
- set(int index, Object o): Replaces the element at a specific index with another element.
- contains(Object o): Checks if the list contains a specific element.
- indexOf(Object o): Returns the index of the first occurrence of a specific element.
- get(int index): Retrieves the element at a specific index.
- clear(): Removes all elements from the list.
- size(): Returns the number of elements in the list.

ArrayList vs. Array

Arrays have a fixed size, while ArrayList can grow dynamically.
ArrayList offers more functionalities than arrays, like removing elements, easily finding elements, resizing, etc.

Using ArrayList

Importing the ArrayList class is needed for using it.
Creating an ArrayList is done using the syntax: ArrayList list = new ArrayList();
Adding elements to an ArrayList is done using the add() method.
Retrieving an element from an ArrayList is done using the get(index) method.
Modifying an existing element in an ArrayList is done using the set(index, value) method.
Determining the size of an ArrayList is done using the size() method.
Looping through elements in an ArrayList can be done with a for loop, a for-each loop, or an iterator (not discussed in the text).

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Description

Explore the fundamentals of loops and arrays in programming. This quiz covers repetition statements, how to declare and initialize arrays, and the concept of two-dimensional arrays. Test your understanding of these essential programming concepts.