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  Using Java keytool programmatically

Java provides a command line tool to access and operate different keystore which store keys and certificates. This tool is named keytool and is located at \bin.  On command line, you can issue below command to generate a keystore named mytest.jks which contains a private key and certificate chain. keytool -genkeypair -alias mykey -keyalg RSA -sigalg SHA256withRSA -dname CN=Java -storetype JKS -keypass password -keystore mytest.jks -storepass password Sometimes, in testing purpose, w...

   JAVA,KEYTOOL     2016-01-09 06:28:07

  Writing Java codes conforming to coding standard

Recently, I was doing some cleanup to one of my current Java project. I find there are many codes which are not conforming to the Java coding standard. So I list them here and hope that people can improve your codes and write maintainable codes. Format source code and manage imports in Eclipse Eclipse provides functions of auto-formatting and imports management, you can use following shortcuts to use these functions. Ctrl+Shift+F --> Format source code Ctrl+Shift+O -- Manage imports an...

   Java, Code standard,Style     2012-09-18 12:50:28

  Replacing small C programs with Haskell

C is the classic go-to tool for small programs that need to be really fast. When scripts.mit.edu needed a small program to be a glorified cat that also added useful HTTP headers to the beginning of its output, there was no question about it: it would be written in C, and it would be fast; the speed of our static content serving depended on it! (The grotty technical details: our webserver is based off of a networked filesystem, and we wanted to avoid giving Apache too many credentials in ca...

   C,Haskell,Small program     2012-01-03 10:51:39

  Traditional recursion vs Tail recursion

Recursion is a frequently adopted pattern for solving some sort of algorithm problems which need to divide and conquer a big issue and solve the smaller but the same issue first. For example, calculating fibonacci  accumulating sum and calculating factorials. In these kinds of issues, recursion is more straightforward than their loop counterpart. Furthermore, recursion may need less code and looks more concise. For example, let's calculate sum of a set of numbers starting with 0 and st...

   ALGORITHM,RECURSION,TAIL RECURSION,TRADITIONAL RECURSION     2016-09-23 23:54:09

  C++ : string beginWith and endWith

C++ is an very powerful programming language. It is efficient and flexible. When writing C++ programs, we may often need to process strings and often we need to check whether a string begin with some substring or end with some substring. We can use following functions to ahieve these:     static bool beginWith(const std::string str,const std::string needle){        return (!str.compare(0,needle.length(),needle));    }    ...

   C++,beginWith,endWith,     2012-08-31 06:53:44

  Why can System.out.println be used to exit while loop

Let's first take a look at one simple Java thread code snippet which is supposed to exit the while loop after the first loop run. public class StopThread { private static boolean stopRequested; public static void main(String[] args) throws InterruptedException { Thread backgroundThread = new Thread(new Runnable() { @Override public void run() { int i = 0; while (!stopRequested) { i++; } } }); backgroundThread.start(); TimeUnit.SECONDS.sleep(1); stopRequested = true; } } But the tr...

   JAVA,THREAD,VOLATILE     2018-12-21 19:25:54

  Generate signed certificate from CSR in Java

In our previous tutorial, we have explained how to generate CSR which can be sent to CA for generating a signed certificate. In this tutorial, we will explain how to generate the signed certificate from CSR in Java. We will not use an actual CA but a self-signed certificate to act as a CA certificate. Since the CSR contains the subject information where a certificate needs to be generated and signed for. The key here is to extract the subject information from the CSR and then set it as the subje...

   JAVA,CSR,SIGN CERTIFICATE     2020-10-24 07:03:17

  Java Sequential IO Performance

Many applications record a series of events to file-based storage for later use.  This can be anything from logging and auditing, through to keeping a transaction redo log in an event sourced design or its close relative CQRS.  Java has a number of means by which a file can be sequentially written to, or read back again.  This article explores some of these mechanisms to understand their performance characteristics.  For the scope of this article I will be using pre-a...

   Java,IO,Sequential,Blocking     2012-02-23 07:09:10

  Use Java ThreadLocal with caution

According to Oracle documentation, ThreadLocal is a class provides thread-local variables. These variables differ from their normal counterparts in that each thread that accesses one (via its get or set method) has its own, independently initialized copy of the variable. ThreadLocal instances are typically private static fields in classes that wish to associate state with a thread. In short, ThreadLocal variables are variables belong to a thread, not a class or an instance of a class. One common...

   JAVA,MEMORY LEAK, THREADLOCAL     2015-11-03 07:31:57

  Google wins the lawsuit against Oracle

According to The Next Web, San Francisco court has made a final decision that Google didn't violate Oracle's Java patent. Although previously some judges and some people in jury said that Google made some mistakes on Java's use. The final decision made by the court saves Google from the charge of Java patent infringement. The next step of this lawsuit was supposed to be the evaluation of the damage and compensation. But now because of court's decision, this step is jumpe...

   Google,Oracle,Java,Anroid     2012-05-24 03:18:11

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