How to generate a CIRCULAR MATRIX using Multi-Dimensional Arrays

I have been asked to write a program for circular matrix in a interview programming round. 

Following program is a generic way of creating a circular matrix:

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package blogspot.thinkwithjava; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; /** * * @author R.D * */ class CircularMatrix { public static void main(String args[]) throws IOException { BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.print("Enter the number of elements : "); int n = Integer.parseInt(br.readLine()); int A[][] = new int[n][n]; int k = 1, c1 = 0, c2 = n - 1, r1 = 0, r2 = n - 1; while (k <= n * n) { for (int i = c1; i <= c2; i++) { A[r1][i] = k++; } for (int j = r1 + 1; j <= r2; j++) { A[j][c2] = k++; } for (int i = c2 - 1; i >= c1; i--) { A[r2][i] = k++; } for (int j = r2 - 1; j >= r1 + 1; j--) { A[j][c1] = k++; } c1++; c2--; r1++; r2--; } /* Printing the Circular Matrix */ System.out.println("The Circular Matrix is:"); for (int i = 0; i < n; i++) { for (int j = 0; j < n; j++) { System.out.print(A[i][j] + "\t"); } System.out.println(); } } }

The output will look like this:

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How to convert java.util.Date to java.sql.Date - JDBC Example

JDBC has their own data types for date and time e.g. java.sql.Date, java.sql.Time and java.sql.TimeStamp to match with database date, time and date time types, we cannot pass java.util.Date directly.
All methods which are suppose to store dates e.g. setDate(input1, input2) expects java.sql.Date, so it becomes essential to know how to convert java.util.Date to java.sql.Date in JDBC.

 You would be surprised to know that java.sql.Date is a subclass of java.util.Date and all it does is suppress or remove time-related fields from java.util.Date.

 It is also a good example of a class which violates Liskov substitution principle, because even though java.sql.Date extends java.util.Date, you cannot pass around it to the method which expect java.util.Date because all time-related methods e.g. getHour(), getMinute() and getSeconds() method throws java.util.NotSupportedException.

Converting java.util.Date to java.sql.Date - Example

Unfortunately, there is no method like toSQLDate() in java.util.Date class to facilitate conversion between util date and SQL date but you can use getTime() method to extract long millisecond value from java.util.Date and create a new java.sql.Date based upon that value as shown below:

Date now = new Date();

java.sql.Date sqlDate = new java.sql.Date(now.getTime());

This is the easiest and right way to convert a java.util.Date to java.sql.Date in Java.

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