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  Convert time to Unix time

Unix time is defined as the number of seconds that have elapsed since midnight Coordinated Universal Time (UTC), 1 January 1970,not counting leap seconds. It is used widely in Unix-like and many other operating systems and file formats. It is neither a linear representation of time nor a true representation of UTC. Unix time may be checked on some Unix systems by typing date +%s on the command line. Sometimes it's a bit difficult to compare times stored in different applications or systems with ...

   UNIX time, Oracle DATE, conversion, timestamp     2013-01-19 09:04:17

  Java Then, Java Now - Looking at the evolution of Java from EE7 to EE9

Java, the programming language developed at Sun Microsystems in the 90s and later acquired by Oracle, is the most common programming environment used today, by developers across the globe. With the diversification of applicability that accompanied the technological boom, Java updates now come as Standard Editions (SE), Enterprise Edition (EE) and Micro Edition (ME). The Java SE contains the core programming logic and platform, used for relatively smaller-scale tasks and academic purposes. Java E...

   JAVA DEVELOPMENT COMPANY     2017-07-05 01:09:28

  ByteBuffer in Java

ByteBuffer is introduced in java.nio since Java 1.4. It provides a way of representing raw structured data such as from a file or from network. It enables fast access of underlying data compared to traditional ways like byte[] Prior to Java 1.4, if you want to represent a structured raw data, you need to create a byte[] and then having a set of checks to delimit the byte array to get the expected tokens. There are three ways to create a ByteBuffer: Wrapping an exiting array by calling ByteBuffe...

   JAVA,BYTEBUFFER,ALLOCATION     2015-07-08 03:17:44

  Java SynchronizedList and Iterator

While reading some material about concurrency, I come up with some writing about using SynchronizedList wrap about normal List to enable synchronization.   But one interesting thing is http://docs.oracle.com/javase/7/docs/api/java/util/Collections.html#synchronizedList%28java.util.List%29   It says     It is imperative that the user manually synchronize on the returned list when iterating over it:     1   List list = Collections.synchronizedList(new A...

       2015-12-03 03:04:08

  Work with MySQL character set and collation

For non-English websites, they often have to deal with character set and collation if they want to store data to and read data from databases with other languages. Character set tells the database which kind of character encoding scheme to use to store or read data, collation can be simply understood as a subset of character set, it tells the database how to sort data. We talk about working with character set and collation of MySQL today.  In MySQL, if we want to store Chinese, Japanese or ...

   MySQL,character set,collation,Chinese,question mark     2012-06-17 07:07:28

  Migrate from MySQL to MariaDB in Ubuntu

The biggest movement of escaping from MySQL in this century starts, openSUSE,Fedora and Arch have started to use MariaDB instead of MySQL as their default database. Many people also dislike the attitude of Oracle on MySQL, so it's reasonable to migrate from MySQL to MariaDB. The whole process is not complicated. Here we share the steps to migrate from MySQL to MariaDB in Ubuntu. Installation procedure: sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 0xcbcb082a1bb943db Modify /etc/a...

   MySQL,MariaDB,Ubuntu     2013-08-13 11:14:51

  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); ...

   Hexadecimal,long,Java,bitwise operation     2014-06-18 23:44:32

  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...

   ConcurrentHashMap,Collections.synchronizedMap     2014-09-18 05:04:59

  Twitter user database is hacked

According to Sina Tech, One hacker from Islamic Republic of Mauritania claimed today that he had acquired Twitter's entire user database and he shared over 15000 user account information on file sharing website Zippyshare.These information include the name of each account on Twitter, username and access tokens of third-party applications which have access to their Twitter accounts(such as Instagram or HootSuite).Twitter has yet to comment on the matter, but the company sent messages urging ...

   Twitter,Hacker,Access token     2013-08-20 10:49:44

  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 ...

   JAVA,KEYSTORE,OVERVIEW,JKS,PKCS12,JCEKS,PKCS11,DKS,BKS     2014-08-18 02:09:54

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