Java Autoboxing — Part 1 MCQs with Explanations

Autounboxing in Java refers to the automatic conversion of a wrapper class object to its corresponding primitive type. For example, converting an Integer object to an int , or a Double object to a double . Let's examine the options: Option A: String text = "Hello"; — This is just assigning a String literal to a String variable, not related to autounboxing. Option B: int value = Integer.parseInt("42"); — This parses a String to a primitive int , but it does not involve autounboxing because no wrapper object is involved. Option C: Double result = 3.14; — This is an example of autoboxing (primitive to wrapper), not autounboxing. Since none of the options demonstrate converting a wrapper object to a primitive type, the correct answer is None of These .

The automatic conversion of primitive types to their corresponding wrapper classes is the correct answer to “What is autoboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`int` is the correct answer to “Which primitive type corresponds to the `Integer` wrapper class in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

It simplifies code by automatically converting between primitive types and their corresponding wrapper classes is the correct answer to “What is the primary benefit of autoboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

Wrapper classes (e.g., `Integer`, `Double`) is the correct answer to “In Java, which classes are used for autoboxing and unboxing operations”. This question is standard in competitive examination syllabi for Java Autoboxing.

It throws a `NullPointerException` is the correct answer to “What happens if you try to unbox a `null` reference in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`=` is the correct answer to “Which operator is used for autoboxing and unboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

Autoboxing is introduced in Java 5.0 and later versions is the correct answer to “Which of the following statements is true about autoboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`.intValue()` is the correct answer to “In Java, which method can be used to perform unboxing”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “What is the result of the following code in Java? Integer x = 5; Integer y = 5; System.out.println(x == y);”. This question is standard in competitive examination syllabi for Java Autoboxing.

`Integer num = 42;` is the correct answer to “Which of the following is an example of autoboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`false` is the correct answer to “What is the result of the following code in Java? Integer a = 1000; Integer b = 1000; System.out.println(a == b);”. This question is standard in competitive examination syllabi for Java Autoboxing.

`int` to `Integer` is the correct answer to “In Java, which of the following is a valid autoboxing conversion”. This question is standard in competitive examination syllabi for Java Autoboxing.

The automatic conversion of wrapper classes to their corresponding primitive types is the correct answer to “What is autounboxing in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`.intValue()` is the correct answer to “In Java, which method can be used to perform autounboxing”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “What is the result of the following code in Java? Double x = 3.5; Double y = 3.5; System.out.println(x.equals(y));”. This question is standard in competitive examination syllabi for Java Autoboxing.

`30` is the correct answer to “In Java, what is the result of the expression `Integer.valueOf(10) + Integer.valueOf(20)`”. This question is standard in competitive examination syllabi for Java Autoboxing.

`Character` is the correct answer to “Which wrapper class corresponds to the `char` primitive type in Java”. This question is standard in competitive examination syllabi for Java Autoboxing.

`No error, it compiles successfully` is the correct answer to “What is the result of the following code in Java? Integer a = 100; int b = a;”. This question is standard in competitive examination syllabi for Java Autoboxing.

`Integer.parseInt()` is the correct answer to “In Java, which method can be used to convert a string to an integer”. This question is standard in competitive examination syllabi for Java Autoboxing.

`Compilation error` is the correct answer to “What is the result of the following code in Java? Integer num = null; int result = num + 5;”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “In Java, what is the result of the expression `new Integer(5) == 5`”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “What is the result of the following code in Java? Integer x = 1000; Integer y = 1000; System.out.println(x.equals(y));”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “In Java, what is the result of the expression `new Integer(5).equals(5)`”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “What is the result of the following code in Java? Integer num1 = 100; Integer num2 = 100; System.out.println(num1 == num2);”. This question is standard in competitive examination syllabi for Java Autoboxing.

`true` is the correct answer to “In Java, what is the result of the expression `Integer.valueOf(10).equals(Integer.valueOf(10))`”. This question is standard in competitive examination syllabi for Java Autoboxing.

Unit Testing is the correct answer to “JUnits are used for which type of testing”. This question is standard in competitive examination syllabi for Java Autoboxing.

They cannot be run automatically is the correct answer to “Which of the below statement about JUnit is false”. This question is standard in competitive examination syllabi for Java Autoboxing.

@Junit is the correct answer to “Which of the below is an incorrect annotation with respect to JUnits”. This question is standard in competitive examination syllabi for Java Autoboxing.

MockJava is the correct answer to “Which of these is not a mocking framework”. This question is standard in competitive examination syllabi for Java Autoboxing.

assert() is the correct answer to “Which method is used to verify the actual and expected results in Junits”. This question is standard in competitive examination syllabi for Java Autoboxing.

== is the correct answer to “What does assertSame() method use for assertion”. This question is standard in competitive examination syllabi for Java Autoboxing.

@RunWith(PowerMockRunner.class) is the correct answer to “How to let junits know that they need to be run using PowerMock”. This question is standard in competitive examination syllabi for Java Autoboxing.

Mockito.when(...).thenReturn(...) is the correct answer to “How can we simulate if then behavior in Junits”. This question is standard in competitive examination syllabi for Java Autoboxing.

@InjectMocks is the correct answer to “What is used to inject mock fields into the tested object automatically”. This question is standard in competitive examination syllabi for Java Autoboxing.

<dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.8.1</version> </dependency> is the correct answer to “How can junits be implemented using maven”. This question is standard in competitive examination syllabi for Java Autoboxing.

Serialization is the correct answer to “Which of the following is not introduced with Java 8”. This question is standard in competitive examination syllabi for Java Autoboxing.

represents supplier of Boolean-valued results is the correct answer to “What is the purpose of BooleanSupplier function interface”. This question is standard in competitive examination syllabi for Java Autoboxing.

Function is the correct answer to “What is the return type of lambda expression”. This question is standard in competitive examination syllabi for Java Autoboxing.

StringList.forEach() is the correct answer to “Which is the new method introduced in java 8 to iterate over a collection”. This question is standard in competitive examination syllabi for Java Autoboxing.