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  ConcurrentHashMap vs Collections.synchronizedMap()

ConcurrentHashMap and Collections.synchronizedMap() both provide thread-safe operations of collections of data. They are used in multithreaded programs to provide both thread safety and performance improvements. In many cases, we can use either of them. But the realization of thread safety is different for these two implementations. ConcurrentHashMap will create an HashEntry[] array internally to store the elements passed in from a Map, while Collections.synchronizedMap() will return a Synchroni...

30,319 1 2          CONCURRENTHASHMAP COLLECTIONS.SYNCHRONIZEDMAP


  Different types of keystore in Java -- JKS

JKS is Java Keystore, a proprietary keystore type designed for Java. It can be used to store private keys and certificates used for SSL communication, it cannot store secret keys however. The keytool shipped with JDKs cannot extract private keys stored on JKS. This type of keystore usually has an extension of jks. Next we will show how to operate the JKS keystore with pure Java code. Create JKS keystore The simplest method to create a JKS keystore to create an empty keystore. We can first get an...

16,865 2 0          DEMO EXAMPLE KEYSTORE JKS


  IDEs for Java programmers

IDEs are great helpers to programmers. They can help programmers write less error-prone programs with less time. They have become an inevitable part of many programmers. As a Java developer, you may be familiar with Eclipse already. But do you know other IDEs for Java programmers? We will give an overview of different IDEs for Java programmers. These IDEs are Eclipse, Intellij IDEA, NetBean and BlueJ. Eclipse Eclipse is the most widely used IDE for Java programmers. It's an open source IDE whic...

6,478 4 0          ECLIPSE JAVA IDE BLUEJ NETBEANS


  Understanding abstract interface in Java

Have you read about an interface declaration as public abstract interface InterfaceName in Java? At the first glance, is it a weird declaration? Why should we declare an interface as abstract? For example, we may see below code in some projects: public abstract interface MyInterface { public void check(); public abstract boolean check(boolean really); } Actually here abstract is redundant, an interface is implicitly abstract, we no need to put an abstract in front of interface. But it do...

3,097 0 0          JAVA ABSTRACT INTERFACE


  Different types of keystore in Java -- Overview

Keystore is a storage facility to store cryptographic keys and certificates. They are most frequently used in SSL communications to prove the identity of servers and clients. A keystore can be a file or a hardware device. Three are three kinds of entries can be stored in a keystore depending on the types of keystores. The three types of entries are: PrivateKey : This is a type of keys which are used in asymmetric cryptography. It is usually protected with password because of its sensitivity. It ...

36,642 4 0          JAVA KEYSTORE OVERVIEW JKS PKCS12 JCEKS PKCS11 DKS BKS


  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...

14,137 2 1          JAVA CERTIFICATE CHAIN CREATION PURE JAVA


  Want to be a Java developer?

Java is one of the top 3 programming languages in the world. It can be used to develop both web applications and desktop applications and more importantly it is cross platform--write once, run everywhere. Also, it's easy to pick up. If you want to be a Java developer, please get to ask yourself whether you know below listed topics. This list is summarized by Vivek Vermani, a Senior Java Developer: For a Core Java Developer , Ffollowing topics should be good. OOPs Concepts Abstract Classes and I...

5,170 2 2          JAVA DEVELOPER RESOURCE


  Hexadecimal and long in Java

Today I encountered a hexadecimal operation problem when I was implementing a bit reverse function for integer type. Basically in the implementation, there is an operation which is to do the bit operation & between one long integer and a hexadecimal number 0x00000000FFFFFFFFF. I was expecting that the high 32 bits of the long integer will be zeroed. But unfortunately I didn't get the expected result. The basic implementation is: long num=0x00F0_0000; num = (num>>16) | (num<<16); ...

3,270 0 0          JAVA HEXADECIMAL LONG BITWISE OPERATION