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Articles by Krantik Chavan
Page 17 of 18
C++ Perform to a 2D FFT Inplace Given a Complex 2D Array
Fast Fourier transform (FFT) is an algorithm to compute the discrete Fourier transform (DFT) and its inverse. Basically Fourier analysis converts time (or space) to frequency and vice versa. A FFT rapidly computes transformations by factorizing the DFT matrix into a product of sparse (mostly zero) factors.AlgorithmBegin Declare the size of the array Take the elements of the array Declare three arrays Initialize height =size of array and width=size of array Create two outer loops to iterate on output data Create two outer loops to iterate on input data Compute real, img and ...
Read MoreWhat is Type_FORWARD_ONLY ResultSet in JDBC?
A ResultSet interface in JDBC represents the tabular data generated by SQL queries. It has a cursor which points to the current row. Initially, this cursor is positioned before the first row.You can retrieve the column value at the current row using the getter methods getInt(), getString(), getDate() etc…To move the cursor and to navigate/iterate through the ResultSet the java.sql.ResultSet interface provides various methods such as next(), Previous(), first(), last(), relative(), absolute(), beforeFirst(), afterLast() etc...Type_FORWARD_ONLY Only ResultSetIn forward only ResultSet you can move the cursor only in forward direction. By default, a ResultSet is of type forward only.
Read MoreWhat is TYPE_SCROLL_INSENSITIVE ResultSet in JDBC?
This represents a scrollable ResultSet i.e. the cursor moves in forward or backward directions. This type of ResultSet is insensitive to the changes that are made in the database i.e. the modifications done in the database are not reflected in the ResultSet.Which means if we have established a connection with a database using JDBC program and retrieved a ResultSet holding all the records in a table named SampleTable and, meanwhile if we add some more records to the table (after retrieving getting the ResultSet), these recent changes will not be reflected in the ResultSet object we previously obtained.ExampleConsider we have ...
Read MoreWhat is TYPE_SCROLL_SENSITIVE ResultSet in JDBC?
This represents is a scrollable ResultSet i.e. the cursor moves in forward or backward directions. This type of ResultSet is sensitive to the changes that are made in the database i.e. the modifications done in the database are reflected in the ResultSet.Which means if we have established a connection with a database using a JDBC program and retrieved a ResultSet holding all the records in a table named SampleTable. Meanwhile, if we have added some more records to the table (after retrieving the ResultSet), these recent changes will be reflected in the ResultSet object we previously obtained.Following is an example ...
Read MoreHow to format and display date in Java as '201904'
To format and display date like this i.e. YearMonth, you need to set the pattern:uuuuMMAt first, set a LocalDate:LocalDate localDate = LocalDate.now();Now format and display date as ‘201904’:localDate.format(DateTimeFormatter.ofPattern("uuuuMM"))Exampleimport java.time.LocalDate; import java.time.format.DateTimeFormatter; public class Demo { public static void main(String[] args) { LocalDate localDate = LocalDate.now(); System.out.println("Date = "+localDate); System.out.println("Date (Year and Month) = "+localDate.format(DateTimeFormatter.ofPattern("uuuuMM"))); } }OutputDate = 2019-04-19 Date (Year and Month) = 201904
Read MoreHow can I display Java date as '12/04/2019'
To format and display date like this i.e. Day/Month/Year, you need to set the pattern:dd/MM/yyyyAt first, set a LocalDate:LocalDate localDate = LocalDate.now();Now format and display date as '12/04/2019':localDate.format(DateTimeFormatter.ofPattern("dd/MM/yyyy"))Exampleimport java.time.LocalDate; import java.time.format.DateTimeFormatter; public class Demo { public static void main(String[] args) { LocalDate date = LocalDate.now(); System.out.println("Date = "+date); DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy"); System.out.println("Formatted Date = "+date.format(formatter)); } }OutputDate = 2019-04-12 Formatted Date = 12/04/2019
Read MoreWhat is the difference between the TYPE_SCROLL_INSENSITIVE and TYPE_SCROLL_SENSITIVE ResultSets in JDBC?
In the TYPE_SCROLL_INSENSITIVE ResultSet, the cursor moves in forward or backward directions. This type of ResultSet is insensitive to the changes that are made in the database i.e. the modifications done in the database are not reflected in the ResultSet.Which means if we have established a connection with a database using a JDBC program and retrieved a ResultSet holding all the records in a table named SampleTable. Meanwhile, if we have added some more records to the table (after retrieving getting the ResultSet), these recent changes will not be reflected in the ResultSet object we previously obtained.In the TYPE_SCROLL_SENSITIVE ResultSet, ...
Read MoreJava Program to convert a list to a read-only list
Let’s say the following is our list which isn’t read-only:List < Integer > list = new ArrayList < Integer > (); list.add(10); list.add(20); list.add(30); list.add(40); list.add(50); list.add(20); list.add(40); list.add(50);Convert the above list to Read-only:list = Collections.unmodifiableList(list);On conversion, now you won’t be add or remove elements from the List. Let us see an example:The following program will give an error because we first update the list to read only and then try to remove an element from it, which is not possible now. The reason is we have converted the list to readonly and you cannot add or remove element from ...
Read MoreWhat is ResultSet Concurrency in JDBC?
The concurrency of the ResultSet object determines whether its contents can be updated or not.The Connection interface provides 3 variants of the createStatement() method where one of the method's signature is as follows:Statement createStatement(int resultSetType, int resultSetConcurrency)This method accepts two integer type variables where one represents the type of the ResultSet and the other represents the Concurrency of the ResultSet.The ResultSet interface provides two values to specify the concurrency of the ResultSet.CONCUR_READ_ONLY: If you set this as a value of the concurrency while creating the ResultSet object you cannot update the contents of the ResultSet you can only read/retrieve them.CONCUR_UPDATABLE: ...
Read MoreWhat is CONCUR_READ_ONLY ResultSet in JDBC? Explain?
In general, you will pass this as a value to the createStatement() method as a value of ResultSet Concurrency type.Statement createStatement(int resultSetType, int resultSetConcurrency)This type of result set is not updatable. i.e. once you get a ResultSet object you cannot update its contents.ExampleSuppose, we have a table named Employee in the database with the following contents:+----+---------+--------+----------------+ | Id | Name | Salary | Location | +----+---------+--------+----------------+ | 1 | Amit | 3000 | Hyderabad | | 2 | Kalyan | 4000 | Vishakhapatnam | | 3 | Renuka | 6000 ...
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