To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) A. assert value == null; - This option is incorrect because the assert statement is used for debugging purposes and is typically disabled in production code. It is not an appropriate way to handle a null value.

Option B) B. assert value !null, “value is null”; - This option is incorrect because the syntax is incorrect. The correct syntax for checking if a value is not null is value != null (without the exclamation mark).

Option C) C. if (value == null) { throw new AssertionException(”value is null”); - This option is incorrect because AssertionException is not a standard exception in Java. It is not appropriate to throw an assertion-specific exception to handle a null value.

Option D) D. if (value == null) { throw new IllegalArgumentException(”value is null”); - This option is correct because IllegalArgumentException is a standard exception in Java that is commonly used to indicate that an argument passed to a method is invalid. Throwing an IllegalArgumentException with an appropriate error message is an appropriate way to handle a null value in this context.

The correct answer is D. This option is correct because it uses the appropriate exception (IllegalArgumentException) to handle a null value.

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To answer this question, we need to understand the concept of abstract classes and how they are declared in Java.

An abstract class is a class that cannot be instantiated and is meant to be extended by other classes. It may contain abstract methods, which are methods without any implementation, as well as regular methods with implementations.

Let's go through each option to understand why it is correct or incorrect:

Option A) public abstract class Canine { public Bark speak(); } This option is incorrect because the abstract method "speak()" is not given an implementation. Abstract methods must be implemented in the concrete subclass that extends the abstract class.

Option B) public abstract class Canine { public Bark speak() { } } This option is correct because it declares an abstract class "Canine" with a concrete method "speak()" that returns a "Bark" object. The method implementation can be empty, as long as it is provided.

Option C) public class Canine { public abstract Bark speak(); } This option is incorrect because the class "Canine" is not declared as abstract, but it contains an abstract method "speak()". Abstract methods can only exist in abstract classes.

Option D) public class Canine abstract { public abstract Bark speak(); } This option is incorrect because the keyword "abstract" should come before the class name, not after it. The correct syntax is "public abstract class Canine".

The correct answer is B. This option is correct because it declares an abstract class "Canine" with a concrete method "speak()" that returns a "Bark" object, even though the implementation is empty.

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• Wrong explanation

To answer this question, we need to understand the JavaBeans standard. The JavaBeans standard is a design pattern for writing reusable and customizable components in Java. According to this standard, the names of methods in JavaBeans should follow specific conventions.

Let's go through each option to determine if it follows the JavaBeans standard:

A. addSize - This method name does not follow the JavaBeans standard. According to the standard, getter and setter methods should have names that start with "get" and "set" respectively.

B. getCust - This method name follows the JavaBeans standard. It starts with "get" and is followed by a capitalized property name ("Cust"). This naming convention is used for getter methods.

C. deleteRep - This method name does not follow the JavaBeans standard. According to the standard, getter and setter methods should have names that start with "get" and "set" respectively.

D. isColorado - This method name follows the JavaBeans standard. It starts with "is" and is followed by a capitalized property name ("Colorado"). This naming convention is used for boolean getter methods.

E. putDimensions - This method name does not follow the JavaBeans standard. According to the standard, getter and setter methods should have names that start with "get" and "set" respectively.

Therefore, the method names that follow the JavaBeans standard are B. getCust and D. isColorado.

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• Wrong explanation