Java Programming

Java MCQ: How does the Files.writeString() method introduced in Java 11 work? a) It appends a string to an existing file b) It writes a string to a file, overwriting any existing content c) It writes a byte array to a file d) It creates a new directory with the given string as the name […]

Java MCQ: What does the Files.readString() method in Java 11 return? a) A List of strings b) A byte array c) A single string containing the file’s content d) A Stream of strings Answer: c) A single string containing the file’s content Explanation: The Files.readString() method, introduced in Java 11, reads the content of a

Java MCQ: Which of the following is a new method added to the String class in Java 11? a) trim() b) strip() c) substring() d) replace() Answer: b) strip() Explanation: The strip() method is one of the new methods added to the String class in Java 11. This method removes all leading and trailing whitespace

Java MCQ: How does the sendAsync() method in Java 11 HttpClient differ from the send() method? a) It sends requests over a different protocol b) It sends requests asynchronously, returning a CompletableFuture c) It sends requests faster d) It sends requests in batches Answer: b) It sends requests asynchronously, returning a CompletableFuture Explanation: The sendAsync()

Java MCQ: What is the return type of the send() method in the Java 11 HttpClient class? a) HttpResponse b) String c) Future d) void Answer: a) HttpResponse Explanation: The send() method in the Java 11 HttpClient class returns an instance of HttpResponse. This method is used to send an HTTP request synchronously, meaning that

Java MCQ: Which method is used to create a new instance of HttpClient in Java 11? a) HttpClient.create() b) HttpClient.newBuilder() c) HttpClient.newHttpClient() d) HttpClient.getInstance() Answer: c) HttpClient.newHttpClient() Explanation: The HttpClient.newHttpClient() method is used to create a new instance of HttpClient in Java 11. This method returns a default HttpClient that can be used to send

Java MCQ: What is the primary use of the Java HTTP Client introduced in Java 11? a) To create TCP connections b) To send and receive HTTP requests and responses c) To manage WebSocket connections d) To encrypt data over a network Answer: b) To send and receive HTTP requests and responses Explanation: The primary

Java MCQ: What does the Local-Variable Syntax for Lambda Parameters in Java 11 allow you to do? a) Define local variables in lambda expressions b) Use the var keyword to declare the types of lambda parameters c) Use instance variables inside lambda expressions d) Automatically infer the types of lambda parameters Answer: b) Use the

Java MCQ: What does the Optional.orElseThrow() method introduced in Java 10 do? a) Returns the contained value if present, otherwise throws NoSuchElementException b) Returns the contained value if present, otherwise returns null c) Returns the contained value if present, otherwise returns a default value d) Returns the contained value if present, otherwise throws IllegalStateException Answer:

Java MCQ: How does the Collectors.toUnmodifiableMap() method handle duplicate keys in Java 10? a) It merges the values associated with duplicate keys b) It throws an IllegalStateException c) It ignores duplicate keys d) It keeps only the first occurrence of the key Answer: b) It throws an IllegalStateException Explanation: The Collectors.toUnmodifiableMap() method, introduced in Java

Java MCQ: What is the purpose of Collectors.toUnmodifiableSet() introduced in Java 10? a) To create a mutable set from a stream b) To create an unmodifiable set from a stream c) To create a sorted set from a stream d) To create a set that allows duplicate elements Answer: b) To create an unmodifiable set

Java MCQ: Which Java 10 feature allows you to collect elements into an unmodifiable list using Collectors? a) Collectors.toUnmodifiableSet() b) Collectors.toUnmodifiableMap() c) Collectors.toUnmodifiableList() d) Collectors.toImmutableList() Answer: c) Collectors.toUnmodifiableList() Explanation: The Collectors.toUnmodifiableList() method, introduced in Java 10, allows you to collect elements into an unmodifiable list. This method is part of the java.util.stream.Collectors class and is

Java MCQ: What is the behavior of the Map.copyOf() method introduced in Java 10 when invoked with a map containing null keys or values? a) It removes the null keys or values from the map b) It replaces null keys or values with empty strings c) It throws a NullPointerException d) It converts null keys

Java MCQ: How does the Set.copyOf() method introduced in Java 10 behave when given a null argument? a) It returns an empty set b) It throws a NullPointerException c) It creates a set with a null element d) It ignores the null argument Answer: b) It throws a NullPointerException Explanation: The Set.copyOf() method, introduced in

Java MCQ: What does the List.copyOf() method introduced in Java 10 return? a) A deep copy of the list b) A shallow copy of the list c) An unmodifiable copy of the list d) A mutable copy of the list Answer: c) An unmodifiable copy of the list Explanation: The List.copyOf() method, introduced in Java

Java MCQ: What is the primary purpose of the var keyword introduced in Java 10? a) To declare a constant variable b) To infer the type of a local variable at compile-time c) To create immutable objects d) To define global variables Answer: b) To infer the type of a local variable at compile-time Explanation:

Java MCQ: What is the behavior of the Map.of() method when invoked with duplicate keys? a) It merges the values of the duplicate keys b) It replaces the previous key with the new one c) It throws an IllegalArgumentException d) It removes the duplicate key Answer: c) It throws an IllegalArgumentException Explanation: The Map.of() method

Java MCQ: Which of the following is true about the Map.ofEntries() method in Java 9? a) It creates a mutable map with a fixed number of entries b) It allows the creation of an immutable map with more than 10 entries c) It creates a map that allows null keys and values d) It replaces

Java MCQ: What is the correct way to define a module in Java 9? a) Using the module keyword in a file named module-info.java b) Using the class keyword in a file named module.java c) Using the package keyword in a file named module.java d) Using the interface keyword in a file named module-info.java Answer:

Java MCQ: Which method in Java 9 is used to create an immutable Map with a variable number of key-value pairs? a) Map.put() b) Map.ofEntries() c) Map.copyOf() d) Map.of() Answer: d) Map.of() Explanation: The Map.of() method introduced in Java 9 is used to create an immutable Map with a variable number of key-value pairs. This

Java MCQ: Which of the following best describes the purpose of the Set.of() method in Java 9? a) To create a mutable set b) To create an immutable set c) To create a set with duplicate elements d) To convert a list to a set Answer: b) To create an immutable set Explanation: The Set.of()

Java MCQ: What happens if you use the Java 9 List.of() method with null elements? a) It creates a List with null elements b) It creates a List and removes the null elements c) It throws a NullPointerException d) It converts null elements to empty strings Answer: c) It throws a NullPointerException Explanation: Using the

Java MCQ: Which statement is true about private methods in interfaces introduced in Java 9? a) They can be called from outside the interface b) They can only be called within default or static methods of the same interface c) They must be overridden by implementing classes d) They are automatically public Answer: b) They

Java MCQ: How do you start a JShell session from the command line? a) Run the command java -jshell b) Run the command jshell c) Run the command java -jar jshell.jar d) Run the command shelljava Answer: b) Run the command jshell Explanation: To start a JShell session from the command line, you run the

Java MCQ: What is a key advantage of using Java modules introduced in Java 9? a) They allow for direct memory access b) They enable better encapsulation and modularization of code c) They improve exception handling d) They increase the speed of the garbage collector Answer: b) They enable better encapsulation and modularization of code