primitive

问题 I have two Arrays of unknown type...is there a way to check the elements are the same: public static boolean equals(Object a , Object b) { if (a instanceof int[]) return Arrays.equals((int[]) a, (int[])b); if (a instanceof double[]){ ////etc } I want to do this without all the instanceof checks.... 回答1: ArrayUtils.isEquals() from Apache Commons does exactly that. It also handles multi-dimensional arrays. 回答2: You should try Arrays.deepEquals(a, b) 回答3: Arrays utilities class could be of help

问题 I've written a piece of java code that when given an array (arrayX), works out the prefix averages of that array and outputs them in another array (arrayA). I am supposed to count the primitive operations and calculate the Big-O notation (which i'm guessing is the overall number of calculations). I have included the java code and what I believe to be the number of primitive operations next to each line, but I am unsure whether I have counted them correctly. Thanks in advance and sorry for my

问题 I just started to work with 3D meshes, oriented to be used for finite element analysis. I would like to model inclusions for materials (any shape, but mainly interested in spheres and ellipsoids) in a cube-like matrix. These inclusions shouldn't be coincident with each other. So I was thinking to use some sort of package for python which can plot primitive objects, look for their intersection (if it exists) and export the geometry (or mesh it and export it). In case of spheres, I was coding

问题 I read that all primitives fall under the System namespace. If I comment out using System , I would expect there to be a build error in my program. However, it is running successfully. Why is this? 回答1: It's because int is an alias for System.Int32 , and since the "Int32" is already prefixed with its namespace (ie. "fully qualified"), the syntax is legal without having to specify using System; at the top of your code. The MSDN snippet below describes this concept- Most C# applications begin

问题 I did some profiling on my application and one of the results turned out that about 18% of memory on the heap is used by objects of type Double . It turns out these objects are the values in Map s, where I cannot use the primitive type. My reasoning is that the primitive type of double consumes less memory than it's object Double . Is there a way to have a map like data structure, that would accept any type as key and a primitive double as values? Main operations would be: insertion (probably

问题 I did some profiling on my application and one of the results turned out that about 18% of memory on the heap is used by objects of type Double . It turns out these objects are the values in Map s, where I cannot use the primitive type. My reasoning is that the primitive type of double consumes less memory than it's object Double . Is there a way to have a map like data structure, that would accept any type as key and a primitive double as values? Main operations would be: insertion (probably

问题 When searching for explanations of how logical equals == works in Java the answers are always something along the lines of: For primitives it returns whether the primitives have the same value (this includes comparing a primitive to its WrapperObject as the WrapperObject gets automatically unboxed to a primitive). For Objects it returns whether they represent the same Object on the Heap. But these explanations all seem to imply that these are 2 different things , that == behaves differently

问题 Is there any operator or trick for such operation? Or is it necessary to use if(5<i && i<10) ? 回答1: There is no such thing in Java (unless you work with booleans). The 5<i results in a boolean on the left side on <10 which the compiler dislikes. 回答2: You cannot chain inequalities. You can, however, define a static boolean method isInRange(value, low, high) that will perform such a check. Some other languages, like Python or Icon, allow this notation. 回答3: You can use a single comparison but

问题 Is there any operator or trick for such operation? Or is it necessary to use if(5<i && i<10) ? 回答1: There is no such thing in Java (unless you work with booleans). The 5<i results in a boolean on the left side on <10 which the compiler dislikes. 回答2: You cannot chain inequalities. You can, however, define a static boolean method isInRange(value, low, high) that will perform such a check. Some other languages, like Python or Icon, allow this notation. 回答3: You can use a single comparison but

问题 I want to do something when creating a string, for example: String = new Proxy(String, { construct: (t, a) => { return { a: 123 } } }) console.log(new String('q')) // { a: 123 } However, if you use primitives, it doesn't work. String = new Proxy(String, { construct: (t, a) => { return { a: 123 } } }) console.log('1') // Expected: { a: 123 }, Actual: 1 Is there any way? then the second question is, when the runtime converts primitives, can I proxy the process? var a = '123' // This is a