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  Generate certificate in Java -- Certificate chain

In previous post, we have introduced the use of Certificate and how to generate self signed certificate using Java. In this post, we will show you how to generate a certificate chain. Sometimes we may only have a certificate request or we don't have a trusted certificate which can be used for business. Now we need to have a trusted CA to sign our certificate so that it can be used on SSL communications. To generate a certificate chain, we may first have our own certificate(A), then we may use ot...

   Java,Certificate chain,Creation, Pure Java     2014-07-30 08:24:52

  Reflection in Java

What is Reflection? Reflection is a feature in Java that allows a program to obtain information about itself at runtime and dynamically manipulate the properties, methods, and constructors of classes or objects. With reflection, we can instantiate objects, call methods, and set properties without knowing the exact class name beforehand. The core of the reflection mechanism is the Class object, which represents a class. The Java Virtual Machine (JVM) automatically creates this Class object when i...

   JAVA REFLECTION,TUTORIAL,FIELD,METHOD     2024-06-27 07:52:12

  Singleton Design Pattern in Java

Singleton is frequently used in applications where resource may be expensive to create and no instance specific state needs to be maintained. For example, when creating database connection, a singleton may be needed. Today we will share the famous Singleton design pattern in Java. 1. Definition Singleton design pattern is a design pattern that restricts the instantiation of a class to one object. It is one of the most well-known design patterns. 2. Application Singleton ...

   DESIGN PATTERN,SINGLETON,MULTITHREAD,JAVA     2020-04-11 02:16:28

  Generating CSR using Java

A CSR(Certificate Signing Request) is a kind of request generated by an application and is to be sent to a Certificate Authority to create a signed certificate which can be distributed. It usually contains certificate information such as subject name, public key info and signature info. In Java, keytool can be used to generate a certificate request with option -certreq.  But sometimes if an application wants to create a CSR programmatically, keytool will not do a favor, instead you should u...

   JAVA,SECURITY,CSR,CERTIFICATE REQUEST     2016-05-25 04:49:17

  Recursive class initialization in Java

When a Java class is referenced and initialized, it has to go through the loading and linking first. Once the loading and linking complete successfully. The class will be initialized. The static variables and constant variables will be initialized during this process. Once the class is initialized, it is ready for use. If when class A is initialized and it is referencing a class B, the class B will also get initialized. But what will happen if class B is referencing class A as well? This is call...

   Java,JVM,class initialization,static final     2015-04-15 21:04:29

  Java Cipher encryption/decryption example

In Java, Cipher is the API for doing data encryption/decryption. Many cryptographic algorithms such as AES, DES, RC4 etc can be specified when creating Cipher instance. The Cipher instance calls the underlying algorithm specific implementation to do the actual encryption/decryption.  Before doing the encryption/decryption, a key needs to be created and it will be used to do the encryption/decryption. A sample program for performing all these is : import java.security.Key; import javax.cryp...

   Java, Java Security, Cipher, Example, Sample     2015-08-14 07:07:10

  Different types of keystore in Java -- Windows-MY

Windows-MY is a type of keystore on Windows which is managed by the Windows operating system. It stores the user keys and certificates which can be used to perform cryptographic operations such as signature verification, data encryption etc. Since it's a kind of native keystore, Java doesn't have a general API to access it. To help Java applications access the keys and certificates stored in Windows-MY keystore, Java provides a separate API -- SunMSCAPI. The SunMSCAPI provider is ...

   JAVA,KEYSTORE,WINDOWS-MY,SUNMSCAPI     2016-01-09 05:45:59

  Why exception would be thrown when deleting element while looping through HashMap in Java

HashMap and other Collection types are frequently used in Java application programming. This post will explain why exception would be thrown when deleting element with Map.remove() while looping through a Map using Iterator. This issue would also occur to other Collection types such as Set, List. Below is a sample code snippet demonstrating the exception thrown. Map<String,String> map = Collections.synchronizedMap(new TreeMap<String,String>()); map.put("key1","value1"); map.put("ke...

   JAVA,HASHMAP,CONCURRENTMODIFICATIONEXCEPTION     2018-06-30 12:49:09

  Apple CEO criticizes Windows 8 on D10

In the D10 Digital Conference held by The Wall Street Journal, Apple’s CEO Tim Cook expressed his sharp criticism about Windows 8 to be launched by Microsoft. According to Cook, the idea of this OS attempting to perfectly apply to both tablet and PC is far from realistic.On D10, Tim Cook said : "[With Windows 8, Microsoft] is pulling all of the leg weight of the PC market. You wind up with something that's very similar to what tablets were 10 years ago. The more you look at combining th...

   Apple CEO,Tim Cook,Windows 8,D10     2012-05-31 05:31:32

  Android socket programming example

Socket is a kind of interface for different sides t communicate, it usually identified by an IP and a port. There are many server side software on a server and they would provide different service. Each server many create some sockets and bind them to some ports so that clients can listen to. Software on the Internet will exchange data though a bidirectional connection established. Each end of the connection has a socket created. In Java, Socket and ServerSocket are in java.net package, ServerSo...

   Android,Socket,Java     2013-05-11 22:17:16

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