Java Methods Quiz

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Questions and Answers

What is the purpose of inheritance in Java?

To define a contract for classes that implement it

To allow a class to inherit properties and behaviors from another class (correct)

To encapsulate data and methods within a single unit

To simplify complex systems by modeling classes based on essential properties and behaviors

What does the length() method return for the string 'RockStar'?

9 (correct)

What does the indexOf method return for the character 'S' in the string 'RockStar'?

5 (correct)

-1

What does the charAt(5) method return for the string 'RockStar'?

t Signup and view all the answers

What does the contains method return for the characters 'tar' in the string 'RockStar'?

false Signup and view all the answers

What does the replace method return for replacing 'Rock' with 'Duke' in the string 'RockStar'?

DukeStar Signup and view all the answers

What is a Java String in technical terms?

An array of characters Signup and view all the answers

Why are Strings important in computer science?

Language symbols are important to meaning and decision making Signup and view all the answers

What is the result of concatenating two strings in Java?

A new string containing the combined characters of the original strings Signup and view all the answers

What does the 'Length' method in Java String class do?

Obtain the length of the string Signup and view all the answers

How is a String represented in Java?

As a series of characters enclosed in double quotes Signup and view all the answers

What is the primary purpose of expressions in Java?

To compute and assign values to variables Signup and view all the answers

Which statement is used to evaluate a condition in Java?

if statement Signup and view all the answers

Which type of statement is used to control the flow of Java code?

Control flow statement Signup and view all the answers

What is the purpose of a loop statement in Java?

To repeat a block of code Signup and view all the answers

What is the purpose of the if-else statement in Java?

To execute a block of code if the condition of the if-block is false Signup and view all the answers

What is the main difference between the if-else statement and the if-else-if ladder?

The if-else statement has only one else block, while the if-else-if ladder can have multiple else-if blocks Signup and view all the answers

In nested if-statements, what happens if the condition of the outer if-statement is false?

The program exits the nested if-statements and continues with the rest of the code Signup and view all the answers

What is the main advantage of using a switch statement over if-else-if statements?

Switch statements provide better readability and are easier to use Signup and view all the answers

When is the for loop in Java used?

When the number of iterations is known Signup and view all the answers

What is the initial capacity of an empty list constructed using the ArrayList class in Java?

10 Signup and view all the answers

Which package is the ArrayList class implemented in?

java.util Signup and view all the answers

What type of implementation does the ArrayList class provide for the List interface?

Dynamic array-like Signup and view all the answers

Study Notes

Inheritance in Java

Inheritance in Java allows classes to inherit properties and methods from parent classes, promoting code reusability and a hierarchical structure.

String Methods

The length() method returns the length of the string, which is 8 for "RockStar".
The indexOf() method returns the index of the first occurrence of the character 'S', which is 5 in "RockStar".
The charAt(5) method returns the character at the specified index, which is 'S' for "RockStar".
The contains() method returns true if the string contains the specified characters, so true for "tar" in "RockStar".
The replace() method returns a new string with the specified replacements, resulting in "DukeStar" for replacing "Rock" with "Duke" in "RockStar".

Java String

In technical terms, a Java String is an immutable sequence of characters represented as a java.lang.String object.

Importance of Strings in Computer Science

Strings are fundamental in computer science for representing and manipulating textual data, crucial for communication, user interaction, and data storage.

String Concatenation

Concatenating two strings in Java results in a new string combining the characters of both original strings.

'Length' Method

The length() method in the Java String class returns the number of characters in the string.

String Representation in Java

In Java, strings are represented as an array of Unicode characters, ensuring efficient handling of text in various languages.

Expressions in Java

The primary purpose of expressions in Java is to compute values, involving variables, operators, and function calls.

Conditional Evaluation

The if statement is used to evaluate a condition in Java, executing code blocks based on the outcome of the comparison.

Control Flow Statements in Java

Control flow statements in Java, including if, else, switch, for, and while, determine the execution order of code blocks based on specific conditions.

Loop Statements

Loop statements, such as for and while, automate repetitive tasks, iterating through blocks of code until a specific condition is met.

if-else Statement

The if-else statement in Java executes one block of code based on a condition, while executing a different block if the condition is false.

if-else-if Ladder vs if-else

The key difference between the if-else statement and the if-else-if ladder lies in the evaluation of multiple conditions. The ladder evaluates conditions sequentially, stopping at the first true condition, while if-else only evaluates two conditions.

Nested if Statements

If the condition of the outer if statement is false in nested statements, the inner statements within that if block are skipped, and the code execution continues with the statements following the outer if.

Advantage of Switch Statement

The main advantage of using a switch statement over if-else-if statements is improved readability and efficiency for evaluating a single variable against multiple potential values.

for Loop Usage in Java

The for loop in Java is typically used when the number of iterations is known beforehand, allowing for controlled iteration over a sequence of values.

ArrayList Initial Capacity

An empty list constructed using the ArrayList class in Java has an initial capacity of 10 elements.

ArrayList Package

The ArrayList class is implemented in the java.util package.

ArrayList Implementation

The ArrayList class provides a dynamic array implementation for the List interface, allowing for efficient insertion and retrieval of elements while maintaining the order.

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Description

Test your knowledge of Java methods with this quiz! Explore key concepts such as method signature, return type, and parameter list. Brush up on your understanding of how methods work within a Java class.