uniqueidentifier

问题 This question already has answers here : Create a GUID in Java (6 answers) Closed last year . I\'m looking for the best way to create a unique ID as a String in Java. Any guidance appreciated, thanks. I should mention I\'m using Java 5. 回答1: Create a UUID. String uniqueID = UUID.randomUUID().toString(); 回答2: If you want short, human-readable IDs and only need them to be unique per JVM run: private static long idCounter = 0; public static synchronized String createID() { return String.valueOf

问题 I know there are a number of similar questions in stackoverflow such as the followings: What\'s a good way to uniquely identify a computer? What is a good unique PC identifier? Unique computer id C# WIN32_Processor::Is ProcessorId Unique for all computers How to uniquely identify computer using C#? ... and dozens more and I have studied them all. The problem is that some of the accepted answers have suggested MAC address as an unique identifier which is entirely incorrect. Some other answers

问题 I am making a analytics system, the API call would provide a Unique User ID, but it\'s not in sequence and too sparse. I need to give each Unique User ID an auto increment id to mark a analytics datapoint in a bitarray/bitset. So the first user encounters would corresponding to the first bit of the bitarray, second user would be the second bit in the bitarray, etc. So is there a solid and fast way to generate incremental Unique User IDs in MongoDB? 回答1: You can, but you should not https://web

问题 I am using this call: Secure.getString(getApplicationContext().getContentResolver(), Secure.ANDROID_ID); To get a UID for the device. I think I am getting the same ID from multiple devices though. Should this be possible? The ID in question is: 9774d56d682e549c and apparently there is an issue with several devices returning this ID http://code.google.com/p/android/issues/list?cursor=10603&updated=10603&ts=1295993403 回答1: Check into this thread,. However you should be careful as it's

问题 So are NFC tags really UNIQUE from each other, at least in their SERIAL NUMBER ? And can we rely on the fact that no 2 NFC tags can have the same serial number? I\'m highly skeptical about this as there are (and will be more) NFC tags out there and I don\'t think anyone is controlling the serials... The reason I\'m asking is that I\'m developing a key based system using NFC tags. I don\'t need to write to the tags, I basically just need their serial numbers. But I need them to be truly unique

问题 I am creating in my app bunch of programmatic View s. As it appeared to be they all by default have the same id=-1 . In order to work with them I need to generate unique id\'s. I have tried several approaches - random number generation and based on current time, but anyway there\'s no 100% guarantee that different Views will have different id\'s Just wondering is there any more reliable way to generate unique ones? Probably there\'s special method/class? 回答1: Just an addition to the answer of

问题 I am creating a new database for a web site using SQL Server 2005 (possibly SQL Server 2008 in the near future). As an application developer, I\'ve seen many databases that use an integer (or bigint , etc.) for an ID field of a table that will be used for relationships. But lately I\'ve also seen databases that use the unique identifier ( GUID ) for an ID field. My question is whether one has an advantage over the other? Will integer fields be faster for querying and joining, etc.? UPDATE: To

问题 Android 4.4 introduced Host-based Card Emulation (HCE). As you know, all NFC cards come with a fixed card ID ( NfcAdapter.EXTRA_ID ). My office door access usually detects the NFC card ID for the authorization. After flashing my phone to KitKat, I tried to scan my phone with the access reader. But whenever the screen turns off and on again, I get a different card ID. I did try keeping the phone screen on, and registering the emulated card ID to the door access system. It managed to grant the

问题 I was going through Id generation section of the Hibernate reference guide and \"java persistence with Hibernate\" There are quite a few options available with Hibernate and JPA combined. I was looking for a further documentation on how to choose the specific id generation strategy. I am also looking for tipping points. For example, hilo strategy is expected to reduce contention. I am assuming there must be a trade off associated with this choice. I want to be educated about the trade offs.

问题 I\'d like to get an id unique to a computer with Java, on Windows, MacOS and, if possible, Linux. It could be a disk UUID, motherboard S/N... Runtime.getRuntime().exec can be used (it is not an applet). Ideas? 回答1: It is common to use the MAC address is associated with the network card. The address is available in Java 6 through through the following API: Java 6 Docs for Hardware Address I haven't used it in Java, but for other network identification applications it has been helpful. 回答2: The