File operation is quite platform dependent. Although Java is a cross platform programming language, the file operation in Java is also platform dependent. The obvious evidence is the file permission check. In Java, we can call canRead(), canWrite() and canExecutable() to check whether the program can read, write or execute the file specified. However, on Windows, when we call canRead() on a File object, we may get unexpected result.Actually, on Windows, when we call canRead() on a File object, we will always get the true returned even if we have denied the read access to the file. There is als...

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 layered on top of CAPI and helps Java platform applications access CAPI cryptographic services using ...

In secondary school, we have learned permutation. Basically, for n numbers, the number of permutations for these n numbers can be calculated to n! which is called 'n factorial'. But to display all the permutations on the screen, we need to use a recursive function. The problem is how to write this function. Next I write a program to display the permutations for n numbers with JavaScript. First, we need to understand that from these n numbers, we can first take any one number from it, and the (n-1) numbers remaining has the similar property as the n numbers, we need to find the permutation...

Similarities:Java and C have same syntax operators.Difference—thinkingTwo paradigms:Java: Object oriented languageC: Structured languageDifferences: --SyntaxNo preprocessorJava does not include a preprocessor and does not define any analogs of the #define, #include, and #ifdef directives. Constant definitions are replaced with static final fields in Java. (See the java.lang.Math.PI field for an example.) Macro definitions are not available in Java, but advanced compiler technology and inlining has made them less useful. Java does not require an&nbs...

TIOBE has released the Programming Community Index for May 2012 a bit late. The top 3 languages do not change compared to last Month TIOBE : C overtakes Java as the No.1 programming language, they are still C,Java and C++. However, the share of Java is continuing dropping, Objective-C is steadily rising  Other languages which have rising trend are Visual Basic.NET，PL/SQL and Logo.The last 8 years not much has changed in the top 10 of the TIOBE index except for Objective-C (in) and Delphi (out). Apart from iPhone language Objective-C, new language adoption appears to be much harder th...

C++ is a complex language, full of subtle traps for the unwary. There is an almost infinite number of ways to screw things up. Fortunately, modern compilers are pretty good at detecting a large number of these cases and notifying the programmer via compile errors or warnings. Ultimately, any error that is compiler-detectable becomes a non-issue if properly handled, as it will be caught and fixed before the program leaves development. At worst, a compiler-detectable error results in lost time while the programmer searches for a solution or workaround.The dangerous errors are the ones that co...

In Go, there is a type called slice which is built on top of array. It's a very convenient type when we want to handle a group of data. This post will explain a subtle but tricky difference between empty slice and nil slice.A nil slice is a slice has a length and capacity of zero and has no underlying array. The zero value of slice is nil. If a slice is declared like below, it is a nil slice.package mainimport "fmt"func main() { var a []string fmt.Println(a == nil)}The output will be true for above code snippet. An empty slice is a slice also has a length and capacity of zero but has unde...

When we are coding we may often see some encoding specifications in our source codes such as UTF-8,GB2312. Do you know what these encoding mean and why we need them? In this post, Julián Solórzano will introduce the most widely used encoding specification around the world accomodating all different character sets in the world.UTF-8 is a method for encoding Unicode characters using 8-bit sequences. Unicode is a standard for representing a great variety of characters from many languages.Something like 40 years ago, the standard for information encoding ASCII was created. ASCII...