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CUSTOMER_CODE SMUDE DIVISION_CODE SMUDE EVENT_CODE APR2016 ASSESSMENT_CODE BCA4020_APR2016 QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 12946 QUESTION_TEXT With an example program explain the use of super keyword in Java. SCHEME OF EVALUATION •Whenever a subclass needs to refer to its immediate superclass, it can do so by use of the keyword super. Ithas two general forms: •The first calls the superclass’ constructor •The second is used to access a member of the superclass that has been hidden by a member of a subclass ( 2 Marks) First use of super: A subclass can call a constructor method defined by its superclass by use of the following form of super: super(parameter-list); Example: classBoxWeight extends Box { double weight; // weight of box // initialize width, height, and depth using super() BoxWeight(double w, double h, double d, double m) { super(w, h, d); // call superclass constructor weight = m; } } ( 4 Marks) Second use of super: •It always refers to the superclass of the subclass in which it is used. This usage has the following general form: super. member Here, member can be either a method or an instance variable •This second form of super is most applicable to situations in which member names of a subclass hide members by the same name in the superclass Example: // Using super to overcome name hiding. class A { inti; } // Create a subclass by extending class A. class B extends A { inti; // this i hides the i in A B(int a, int b) { super.i = a; // i in A i = b; // i in B } void show() { System.out.println("i in superclass: " + super.i); System.out.println("i in subclass: " + i); } } classUseSuper { public static void main(String args[]) { B subOb = new B(1, 2); subOb.show(); } } This program displays the following: i in superclass: 1 i in subclass: 2 (4 Marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72589 QUESTION_TEXT a. b. SCHEME OF EVALUATION Addresses on WWW are represented in Java by URL objects. A URL represents any type of information which has to be linked with web. The URL is set up to perform certain activities when a connection is made to it such as loading a web page or downloading a file. URLs are a bit more user friendly to work with than the sockets. (2 marks) a. The URL Class: The URL class transforms a URL string into an object that can then be manipulated using associated methods. These methods serve purposes such as getting the filename, protocol, and hostname. URL also has methods that can open and maintain the data connection of an input stream. b. URLConnection Class: URL Connection Class is another abstract class used to create and control a connection to a platform and firewall Specific location. It is a simplified version of connection interface for the URL class. c. The URLEncoder Class: the URLEncoder Class takes a string a text and turns it into the x-www-form-urlencoded format, which is a MIME format. This can then be used in conjunction with the URL class. d. The URLStreamHandler Class: The URLStreamHandler Class is an abstract class. Its purpose is to create a format for opening a stream connection to a specific URL. This class is concerned with the protocol of What is an URL Object in java? Explain the various URL objects. the URL. If programmer wants to create a new URL stream protocol, it is necessary to implement the methods specified in this abstract class. (2 marks each) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72591 QUESTION_TEXT Explain the tools in the JDK SCHEME OF EVALUATION Naming= 3marks Description = 7 marks TOTAL 10 MARKS QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 72593 QUESTION_TEXT What are the various methods available in RemoteObject class. * * SCHEME OF EVALUATION * * * RemoteArray RemoteBoolean RemoteByte RemoteChar RemoteClass * RemoteDouble * RemoteField * RemoteFloat * RemoteInt * RemoteLong * RemoteShort * RemoteString * RemoteThread * RemoteThreadGroup * RemoteValue Any 10 methods = 10 marks. (1* 10 =Total 10 marks) QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 120576 QUESTION_TEXT What are the different Exception handling techniques? Explain with an example. Try Block Try { //statements that may cause an exception } SCHEME OF EVALUATION Nested try statement ( example) ( 3.5 marks) Catch Block try { //statements that may cause an exception } Catch ( ) { // error handling code example (3.5 marks) } finally block finally { closeFile( ); (3marks) } QUESTION_TYPE DESCRIPTIVE_QUESTION QUESTION_ID 120582 QUESTION_TEXT What is Java IDL? Explain. 1. Java IDL is a technology for distributed objects – i.e. objects interacting on different platform across a network. IDL stands for Interface Definition Language. 2. Java IDL is similar to RMI, which supports distributed objects written entirely in the Java programming language. SCHEME OF EVALUATION However, Java IDL enable objects interact regardless of whether they’re written in the Java programming language or another language such as C, C++, COBOL or others. 3. Java IDL is based on the Common Object Request Brokerage Architecture, an industry standard distributed object model. 4. A key feature of CORBA is IDL, a language –neutral Interface Definition Language. Each language that supports CORBA has its own IDL mapping and as its name implies, Java IDL supports the mapping for Java. CORBA and the IDL mappings are the work of an industry consortium known as the OMG or Object Management Group. 5. TO support interaction between objects in separate programs Java IDL provides an Object Request Broker, or ORB. The Orb is a class library that enables low level communication between Java IDL applications and other CORBA compliant applications. (10 marks)