Tag: web technology

Questions Related to web technology

Given: public static void before() { Set set = new TreeSet(); set.add("2"); set.add(3); set.add("1"); Iterator it = set.iterator(); while (it.hasNext()) System.out.print(it.next() + " "); } Which statements are true?
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  1. The before() method will print 1 2

  2. The before() method will print 1 2 3

  3. The before() method will print three numbers, but the order cannot be determined

  4. The before() method will not compile

  5. The before() method will throw an exception at runtime

Show answer
Correct Option: E

What is output to the web page on the second access to the same instance of the following JSP? (Choose one.) Chapter 6 Question 2

Chapter 6 Question 2
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  1. 0

  2. 1

  3. 2

  4. 3

  5. 4

  6. Page does not translate.

Show answer
Correct Option: D

Which architecture does PS framework follow
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  1. Hibernate Architecture

  2. Struts Architecture

  3. MVC Architecture

  4. Web Architecture

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Correct Option: C

In the UML notation, parameterized (generic) classes are represented by
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  1. the normal class representation with a dotted arrow pointing at the template parameter classes

  2. the normal class representation but shaded grey.

  3. the normal class representation with a dotted outline and the names of its parameter classes listed on the top right-hand corner.

  4. the normal class representation with a rectangular box in its top left-hand corner.

  5. Its a trick question - parameterized classes can't be specified in the UML notation.

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Correct Option: C

Which of the following are true statements about the JavaServer Page life cycle? (Choose two.)
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  1. The _jspService() method is called from the generated servlet's service() method.

  2. jspInit() is only ever called on the first request to a JSP instance.

  3. jspDestroy() is only ever called on the last request to a JSP instance.

  4. All servlet methods are accessible from the jspInit() method.

  5. You cannot override or provide a no-parameter init() method in a JSP page.

Show answer
Correct Option: A,D

Which of the following techniques is likely to return an initialization parameter for a JSP page? (Choose two.)
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Show answer
Correct Option: B,D

What will be the result of pressing the submit button in the following HTML form? (Choose two.)

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  1. A request is sent with the HTTP method HEAD.

  2. A request is sent with the HTTP method POST.

  3. A request is sent with the HTTP method GET.

  4. The parameter fullName is the only parameter passed to the web server in the request URL.

  5. The parameters fullName and sbmButton are passed to the web server in the request URL.

  6. The parameter fullName is the only parameter passed to the web server as part of the request body.

Show answer
Correct Option: C,F

Which of the following are valid servlet methods that match up with HTTP methods? (Choose four.)

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  1. doGet()

  2. doPost()

  3. doConnect()

  4. doOptions()

  5. doHead()

  6. doRequest()

Show answer
Correct Option: A,B,D,F

AI Explanation

To answer this question, you need to understand the relationship between servlet methods and HTTP methods.

In the Java Servlet API, there are several methods that correspond to different HTTP methods. These methods are used to handle requests from clients and provide appropriate responses. The commonly used methods are:

A. doGet() - This method is used to handle the GET requests. It retrieves information from the server and sends it back to the client.

B. doPost() - This method is used to handle the POST requests. It submits data to the server for processing.

C. doConnect() - This is not a valid servlet method. There is no HTTP method called CONNECT.

D. doOptions() - This method is used to handle the OPTIONS requests. It provides information about the communication options available for the requested resource.

E. doHead() - This method is used to handle the HEAD requests. It retrieves the headers of the response without the response body.

F. doRequest() - This is not a valid servlet method. There is no HTTP method called REQUEST.

Based on the above explanations, the valid servlet methods that match up with HTTP methods are A. doGet(), B. doPost(), D. doOptions(), and F. doRequest().

Therefore, the correct answer is A, B, D, F.

Which statements are true about comparing two instances of the same class, given that the equals() and hashCode() methods have been properly overridden? (Choose all that apply.)

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  1. If the equals() method returns true, the hashCode() comparison == might return false

  2. If the equals() method returns false, the hashCode() comparison == might return true

  3. If the hashCode() comparison == returns true, the equals() method must return true

  4. If the hashCode() comparison == returns true, the equals() method might return true

  5. If the hashCode() comparison != returns true, the equals() method might return true

Show answer
Correct Option: B,D

AI Explanation

To answer this question, we need to understand the concepts of the equals() and hashCode() methods in Java.

The equals() method is used to compare two objects for equality. It is typically overridden to compare the values of the instance variables of the objects.

The hashCode() method is used to generate the hash code of an object. It is also typically overridden to generate a hash code based on the values of the instance variables.

Now, let's go through each option to understand why it is correct or incorrect:

Option A) If the equals() method returns true, the hashCode() comparison == might return false.

  • This option is incorrect. According to the contract between the equals() and hashCode() methods, if two objects are equal according to the equals() method, their hash codes must be equal as well. Therefore, the hashCode() comparison == should return true in this case.

Option B) If the equals() method returns false, the hashCode() comparison == might return true.

  • This option is correct. If two objects are not equal according to the equals() method, their hash codes can still be equal. This is because different objects can generate the same hash code, but it does not necessarily mean that they are equal.

Option C) If the hashCode() comparison == returns true, the equals() method must return true.

  • This option is incorrect. While it is true that equal objects must have equal hash codes, the reverse is not necessarily true. Two objects can have the same hash code, but their values may be different, resulting in the equals() method returning false.

Option D) If the hashCode() comparison == returns true, the equals() method might return true.

  • This option is correct. If two objects have the same hash code, it is possible that they are equal according to the equals() method. However, it is also possible that they are not equal.

Option E) If the hashCode() comparison != returns true, the equals() method might return true.

  • This option is incorrect. If two objects have different hash codes, it means that they are not equal according to the equals() method. The equals() method should always return false in this case.

Therefore, the correct answers are: B. If the equals() method returns false, the hashCode() comparison == might return true. D. If the hashCode() comparison == returns true, the equals() method might return true.

Given: import java.util.*; class MapEQ { public static void main(String[] args) { Map m = new HashMap(); ToDos t1 = new ToDos("Monday"); ToDos t2 = new ToDos("Monday"); ToDos t3 = new ToDos("Tuesday"); m.put(t1, "doLaundry"); m.put(t2, "payBills"); m.put(t3, "cleanAttic"); System.out.println(m.size()); } } class ToDos{ String day; ToDos(String d) { day = d; } public boolean equals(Object o) { return ((ToDos)o).day == this.day; } // public int hashCode() { return 9; } } Which is correct? (Choose all that apply.)

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  1. As the code stands it will not compile

  2. As the code stands the output will be 2

  3. As the code stands the output will be 3

  4. If the hashCode() method is uncommented the output will be 2

  5. If the hashCode() method is uncommented the output will be 3

  6. If the hashCode() method is uncommented the code will not compile

Show answer
Correct Option: C,D

AI Explanation

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

Option A) As the code stands, it will not compile - This option is incorrect. The code provided does compile without any errors.

Option B) As the code stands, the output will be 2 - This option is incorrect. The output will not be 2 because the equals() method in the ToDos class is not properly overridden.

Option C) As the code stands, the output will be 3 - This option is correct. The output will be 3 because the equals() method in the ToDos class is comparing the day field of the objects. Since t1 and t2 have the same value for day ("Monday"), they are considered equal, but they are distinct objects, so both of them are added to the map. Therefore, the map contains 3 entries: t1 -> "doLaundry", t2 -> "payBills", and t3 -> "cleanAttic".

Option D) If the hashCode() method is uncommented, the output will be 2 - This option is correct. If the hashCode() method is uncommented, the output will be 2 because the hashCode() method is used to determine the bucket in which to store the key-value pair in the HashMap. Since the hashCode() method is not overridden in the ToDos class, it uses the default implementation from the Object class, which generates a unique hash code for each object. As a result, t1 and t2 will generate different hash codes, and the map will consider them as distinct keys, resulting in only two entries: t2 -> "payBills" and t3 -> "cleanAttic".

Option E) If the hashCode() method is uncommented, the output will be 3 - This option is incorrect. If the hashCode() method is uncommented, the output will be 2 as explained in option D.

Option F) If the hashCode() method is uncommented, the code will not compile - This option is incorrect. Uncommenting the hashCode() method will not cause any compilation errors.

The correct answer is Option C and Option D. These options are correct because they accurately describe the behavior of the code provided.