convert .pem file to .ppk using puttygen - AWS

PEM-Privacy Enhanced Mail is a Base64 encoded DER certificate file format.  PEM certificates are frequently used for web servers as they can easily be translated into readable data using a simple text editor.  Generally when a PEM encoded file is opened in a text editor, it contains very distinct headers and footers.

while creating an instance in Amazon EC2 you will be required to create Key Pairs and .pem file will be generated. I have shown in the below images how to convert .pem file to .ppk file format using puttygen in the below images.

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Java Program to Print Square Pattern with Stars

This is a very basic program for beginners who starts learning for loop. This is the best example to understand how the nested loops works. In our program we are going to print the below square star (* ) pattern as shown in the image.

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How to run two Tomcat Instances on same machine

Sometimes you are forced to work multiple projects at a time, using two work-spaces using IDE's like MyEclipse or Eclipse or NetBeans. In this situation you should run both the tomcat servers to test your changes at a time from your local. If you run both Tomcat servers at a time from different workspaces you will get the error message as showing below:

"Port 8080 required by Tomcat v8.0 Server at localhost is already in Use."

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Java - Unable to Split a String on Caret (^) symbol as a delimiter

In Java Regular Expressions , Caret ( ^ ) is a Special character. Here it means "it should match the beginning" of an input.

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Java Program to find Perimeter of a Circle

The Mathematical equation to find Perimeter or Circumference of a Circle is C=2πr. We can write hte above equation in our program as 2*Math.PI*r

In this tutorial we will learn how to calculate Perimeter(Circumference) of a Circle using java program. To write this program we are using predefined classes like Math, Scanner or BufferedReader. BufferedReader used to read the value of radius at runtime or from console.

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Java Program to Calculate Area of a Circle

The Mathematical formula to find Area of a Circle is : A= πr2 or we can write it as given below.
area = pi * radius * radius

So, to find Area of a circle we need the values of 'pi' and radius. In java we have predefined Mathematical value for pi is defined in java.lang.Math.PI = 3.141592653589793. PI is a static final value.

In our program we need to read radius value from the console by using BufferedReader or Console classes.

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