Java 8 Features and Multithreading

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Questions and Answers

What is the primary purpose of the Optional class in Java 8?

To avoid null pointer exceptions (correct)

To facilitate functional programming

To provide a concise way to represent single-method interfaces

To synchronize thread access to shared resources

What is the syntax for a lambda expression in Java 8?

(parameters) -> {code} (correct)

{code} (parameters) ->

{code} (parameters) =>

(parameters) => {code}

What is the purpose of the default method in Java 8 interfaces?

To facilitate functional programming

To provide a concise way to represent single-method interfaces

To synchronize thread access to shared resources

To add new methods to interfaces without breaking existing implementations (correct)

What is the primary purpose of thread synchronization in Java?

To coordinate access to shared resources Signup and view all the answers

What is a deadlock in multithreading?

A situation where two or more threads are blocked indefinitely Signup and view all the answers

What is the purpose of the Runnable interface in Java?

To create and execute threads Signup and view all the answers

What is the default behavior of the decision tree algorithm in Weka?

It prunes the tree to improve generalization Signup and view all the answers

What is the purpose of the minNum parameter in the decision tree algorithm?

To define the minimum number of instances in a leaf node Signup and view all the answers

What is the name of the decision tree algorithm in Weka that is an advanced version of the REPTree?

J48 Signup and view all the answers

What does setting the noPruning parameter to True do?

It turns off pruning Signup and view all the answers

What type of problem can the k-nearest neighbors algorithm be used for?

Both classification and regression Signup and view all the answers

How can you visualize a decision tree in Weka?

By right-clicking on the 'Result list' and clicking 'Visualize Tree' Signup and view all the answers

What is the primary purpose of the 5 classification algorithms discussed in the context of Weka?

To provide a starting point for solving a classification problem Signup and view all the answers

What is the characteristic of the input variables in the Ionosphere dataset?

They are all numeric variables with the same scale Signup and view all the answers

What is the task in the Ionosphere binary classification problem?

To predict whether or not there is structure in the ionosphere Signup and view all the answers

What is the next step after loading the Ionosphere dataset in the Weka Explorer?

Click the “Classify” button to open the Classify tab Signup and view all the answers

What is the reported accuracy of top results in the Ionosphere classification problem?

Around 98% accuracy Signup and view all the answers

What is the purpose of the Weka Explorer interface?

To explore and test machine learning algorithms Signup and view all the answers

What is the default search algorithm used in the k-Nearest Neighbors Algorithm?

LinearNN Search Signup and view all the answers

What is the purpose of normalizing input data in Support Vector Machines?

To convert nominal values to numerical values Signup and view all the answers

What is the default distance function used in the k-Nearest Neighbors Algorithm?

Euclidean distance Signup and view all the answers

What is the purpose of trying different k values and distance measures in the k-Nearest Neighbors Algorithm?

To find the optimal combination for a specific problem Signup and view all the answers

What type of classification problems were Support Vector Machines originally developed for?

Binary classification problems Signup and view all the answers

What is the accuracy of the k-Nearest Neighbors Algorithm with the default configuration on the Ionosphere dataset?

86% Signup and view all the answers

Study Notes

Java 8 Features

Lambda Expressions

A concise way to represent a single-method interface
Allows for functional programming
Syntax: (parameters) -> {code}

Functional Interfaces

An interface with a single abstract method (SAM)
Can be used with lambda expressions
Examples: Runnable, Callable

Method References

A shorthand for lambda expressions
Syntax: Classname::methodName
Can be used to refer to existing methods or constructors

Default Methods

Allows adding new methods to interfaces without breaking existing implementations
Can be used to provide default implementations for interface methods
Syntax: default return-type methodName(parameters) {code}

Optional Class

A container for a value that may or may not be present
Can be used to avoid null pointer exceptions
Methods: isPresent(), get(), orElse()

Multithreading

Thread Creation

Can be created using Thread class or Runnable interface
Thread class provides a start() method to start the thread
Runnable interface provides a run() method to be executed by the thread

Thread Synchronization

Used to coordinate access to shared resources
Methods: synchronized block, wait(), notify(), notifyAll()

Thread Safety

Ensuring that multiple threads can access shared resources without causing errors
Techniques: atomic operations, locks, immutable objects

Deadlock

A situation where two or more threads are blocked indefinitely
Caused by circular dependencies between threads
Can be avoided by using deadlock-avoidance algorithms or careful design

Thread States

Newborn: thread is created but not started
Runnable: thread is running or ready to run
Running: thread is currently executing
Waiting: thread is waiting for some event to occur
Sleeping: thread is sleeping for a specified amount of time
Blocked: thread is blocked due to I/O or synchronization
Dead: thread has finished execution

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Description

Test your knowledge of Java 8 features such as lambda expressions, functional interfaces, and method references, as well as multithreading concepts like thread creation, synchronization, and deadlock avoidance.