Delphi Sample Technical Placement Paper

7/29/2019 Delphi Sample Technical Placement Paper

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Delphi Technical Latest Sample Placement Paper1. How are the wait/signal operations for monitor different from those

for semaphores?

ANS: If a process in a monitor signal and no task is waiting on the

condition variable, the signal is lost. So this allows easier program

design. Whereas in semaphores, every operation affects the value of

the semaphore, so the wait and signal operations should be perfectly

balanced in the program.

2. How do I create a subscript operator for a Matrix class?

ANS: Use operator () rather than operator [].When you have multiple subscripts, the cleanest way to do it is with

operator () rather than with operator []. The reason is that operator []

always takes exactly one parameter, but operator () can take any

number of parameters (in the case of a rectangular matrix, two

parameters are needed).

For example:

class Matrix {

public:

Matrix(unsigned rows, unsigned cols);

double& operator() (unsigned row, unsigned col); subscript operators

often come in pairs double operator() (unsigned row, unsigned col)

const; subscript operators often come in pairs

...

~Matrix(); // Destructor

Matrix(const Matrix& m); // Copy constructor

Matrix& operator= (const Matrix& m); // Assignment operator

... private:

unsigned rows_, cols_;

double* data_;

};


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inline

Matrix::Matrix(unsigned rows, unsigned cols)

: rows_ (rows)

, cols_ (cols)

//data_ = rows_ || col >= cols_)throw BadIndex("Matrix subscript out of bounds");

return data_[cols_*row + col];

}

inline

double Matrix::operator() (unsigned row, unsigned col) const

{

if (row >= rows_ || col >= cols_)

throw BadIndex("const Matrix subscript out of bounds");return data_[cols_*row + col];

}

Then you can access an element of Matrix m using m(i,j) rather than

m[i][j]:


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int main()

{

Matrix m(10,10); m(5,8) = 106.15; std::cout


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10.What is Zorder Method?

ANS: Object.Zorder = 1 or 0 Place a Specified mdiform form or control

at the front or back of the z-order with n its Graphical Level.11.How can I customize the serialization process?

I.e. how can one have a control over the serialization process?

ANS: Yes it is possible to have control over serialization process. The

class should implement Externalizable interface. This interface contains

two methods namely readExternal and writeExternal. You should

implement these methods and write the logic for customizing the

serialization process.

12.What is the different between Microsoft ODBC Driver and OracleOBDC Driver?

ANS: Microsoft ODBC driver will support all the methods and properties

of Visual Basic. Whereas the Oracle not.

13.What is the common usage of serialization?

ANS: Whenever an object is to be sent over the network, objects need

to be serialized. Moreover if the state of an object is to be saved,

objects need to be serialized.14.How do I serialize an object to a file?

ANS: The class whose instances are to be serialized should implement

an interface Serializable. Then you pass the instance to the

ObjectOutputStream which is connected to a fileoutputstream. This will

save the object to a file.

15.What one should take care of while serializing the object?

ANS: One should make sure that all the included objects are alsoserializable. If any of the objects is not serializable then it throws a

NotSerializableException.

16.What if I write static public void instead of public static void?

ANS: Program compiles and runs properly.


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17.What if the static modifier is removed from the signature of the

main method?

ANS: Program compiles. But at runtime throws an error

NoSuchMethodError.

18.What is the diff between RDO and ADO?

ANS: RDO is Hierarchy model whereas ADO is Object model. ADO can

access data from both flat files as well as the data bases. I.e., It is

encapsulation of DAO, RDO and OLE that is why we call it as OLE-DB

Technology.

19. Have you create Properties and Methods for your own Controls?

ANS: Properties Public variable of a Class & Method Public procedure of

a class.

20.How to change the Mouse Pointer?

ANS: Screen.MousePointer = VBHourGlass/VBNormal.

21.What if I do not provide the String array as the argument to the

method?

ANS: Program compiles but throws a runtime error

NoSuchMethodError.

22.What is the difference between Property Get, Set and Let?

ANS: Set Value is assigned to ActiveX Object from the form.

Let Value is retried to ActiveX Object from the form.

Get- Assigns the value of an expression to a variable or property.

23.How can one prove that the array is not null but empty?

ANS: Print args.length. It will print 0. That means it is empty. But if it

would have been null then it would have thrown a

NullPointerException on attempting to print args.length.

24.What are the Style properties of List Box?

ANS: Simple Single Select, Extended. Multiple Select.


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25.What environment variables do I need to set on my machine in

order to be able to run Java programs?

ANS: CLASSPATH and PATH are the two variables.

26.What is Collection Objects?

ANS: Similarly to arrays but is preferred over an array because of the

following reasons.

1. A collection objects uses less Memory than an array.

2. It provides methods to add and delete members.

3. It does not required reason statement when objects are added or

deleted.

4. It does not have boundary limitations.

27.Can an application have multiple classes having main method?

ANS: Yes it is possible. While starting the application we mention the

class name to be run. The JVM will look for the Main method only in the

class whose name you have mentioned. Hence there is not conflict

amongst the multiple classes having main method.

28.In project properties if we set Unattended what is it mean?

ANS: This cannot have user interface. This can be used for the COM

creation.

29. What are Checked and UnChecked Exception?

ANS: A checked exception is some subclass of Exception (or Exception

itself), excluding class RuntimeException and its subclasses. Making an

exception checked forces client programmers to deal with the

possibility that the exception will be thrown. e.g., IOException thrown

by java.io.FileInputStreams read () method.Checked exceptions are RuntimeException and any of its subclasses.

Class Error and its subclasses also are unchecked. With an unchecked

exception, however, the compiler doesnt force client programmers

either to catch the exception or declare it in a throws clause. In fact,


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client programmers may not even know that the exception could be

thrown. e.g., StringIndexOutOfBoundsException thrown by Strings

charAt () method Checked exceptions must be caught at compile time.

Runtime exceptions do not need to be. Errors often cannot be.

30.Handling Error in Calling chain.

ANS: This will call the top most error where the error is handled.

31.What is a Cartesian product in PL/SQL?

ANS: When a Join condition is not specified by the programmer or is

invalid (fails), PL/SQL forms a Cartesian product.

In a Cartesian product, all combinations of rows will be displayed.For example, All rows in the first table are joined to all rows in the

second table. It joins a bunch of rows and its result is rarely useful

unless you have a need to combine all rows from all tables.

32.Why we use Treeview Control?

ANS: To list the hierarchical list of the node objects. Such of files and

Directories.

33.What is the purpose of garbage collection in Java, and when is it

used?

ANS: The purpose of garbage collection is to identify and discard

objects that are no longer needed by a program so that their resources

can be reclaimed and reused. A Java object is subject to garbage

collection when it becomes unreachable to the program in which it is

used.

34.What is view Port?

ANS: The area under which the container provides the view of theActiveX Document is known as a view port.

35.What are the Style Properties of Combo Box?

ANS: Simple, Dropdown list We can type and select. Dropdown Combo

Only Drop Down.


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36.What is Mixed Cursors?

ANS: Static + Keyset.

37.What is HashMap and Map?

ANS: Map is Interface and Hashmap is class that implements that.

38.Describe synchronization in respect to multithreading?

ANS: With respect to multithreading, synchronization is the capability

to control the access of multiple threads to shared resources. Without

synchronization, it is possible for one thread to modify a shared

variable while another thread is in the process of using or updating

same shared variable. This usually leads to significant errors.

39.Difference between HashMap and HashTable?

ANS: The HashMap class is roughly equivalent to Hashtable, except that

it is unsynchronized and permits nulls. (HashMap allows null values as

key and value whereas Hashtable doesnt allow). HashMap does not

guarantee that the order of the map will remain constant over time.

HashMap is non-synchronized and Hashtable is synchronized.

40.Drag and Drop state numbers and functions?

ANS: State 0 Source control is being dragged with the range of a target.

1 Out of the range of a target.

2 One position in the target to another.

Delphi Sample Technical Placement Paper

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