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Search found 94 results on 4 pages for 'biginteger'.

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  • simple proof that GUID is not unique

    - by Kai
    I'd like to prove that a GUID is not unique in a simple test program. I expected this to run for hours but it's not working. How can I make it work? BigInteger begin = new BigInteger((long)0); BigInteger end = new BigInteger("340282366920938463463374607431768211456",10); //2^128 for(begin; begin<end; begin++) Console.WriteLine(System.Guid.NewGuid().ToString()); I'm using C#

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  • Java: confirm method Binary division and find remainder is correct?

    - by cadwag
    I am parsing binary files and have to implement a CRC algorithm to ensure the file is not corrupted. Problem is that I can't seem to get the binary math working when using larger numbers. The example I'm trying to get working: BigInteger G = new BigInteger("11001", 2); BigInteger M = new BigInteger("1110010000", 2); BigInteger R = M.remainder(G); I am expecting: R = "0101" But I am getting: R = "1100" I am assuming the remainder of 0101 is correct since it is given to me in this book I am using as a reference for the CRC algorithm (it's not based in Java), but I can't seem to get it working. I can get small binary calculations to work that I have solved by hand, but not the larger ones. I'll admit that I haven't worked the larger ones by hand yet, that is my next step, but I wanted to see if someone could point out a glaring flaw I have in my code. Can anyone confirm or deny that my methodology is correct? Thanks

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  • [Java] RSA BadPaddingException : data must start with zero

    - by Robin Monjo
    Hello everyone. I try to implement an RSA algorithm in a Java program. I am facing the "BadPaddingException : data must start with zero". Here are the methods used to encrypt and decrypt my data : public byte[] encrypt(byte[] input) throws Exception { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");// cipher.init(Cipher.ENCRYPT_MODE, this.publicKey); return cipher.doFinal(input); } public byte[] decrypt(byte[] input) throws Exception { Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");/// cipher.init(Cipher.DECRYPT_MODE, this.privateKey); return cipher.doFinal(input); } privateKey and publicKey attributes are read from files this way : public PrivateKey readPrivKeyFromFile(String keyFileName) throws IOException { PrivateKey key = null; try { FileInputStream fin = new FileInputStream(keyFileName); ObjectInputStream ois = new ObjectInputStream(fin); BigInteger m = (BigInteger) ois.readObject(); BigInteger e = (BigInteger) ois.readObject(); RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(m, e); KeyFactory fact = KeyFactory.getInstance("RSA"); key = fact.generatePrivate(keySpec); ois.close(); } catch (Exception e) { e.printStackTrace(); } return key; } Private key and Public key are created this way : public void Initialize() throws Exception { KeyPairGenerator keygen = KeyPairGenerator.getInstance("RSA"); keygen.initialize(2048); keyPair = keygen.generateKeyPair(); KeyFactory fact = KeyFactory.getInstance("RSA"); RSAPublicKeySpec pub = fact.getKeySpec(keyPair.getPublic(), RSAPublicKeySpec.class); RSAPrivateKeySpec priv = fact.getKeySpec(keyPair.getPrivate(), RSAPrivateKeySpec.class); saveToFile("public.key", pub.getModulus(), pub.getPublicExponent()); saveToFile("private.key", priv.getModulus(), priv.getPrivateExponent()); } and then saved in files : public void saveToFile(String fileName, BigInteger mod, BigInteger exp) throws IOException { FileOutputStream f = new FileOutputStream(fileName); ObjectOutputStream oos = new ObjectOutputStream(f); oos.writeObject(mod); oos.writeObject(exp); oos.close(); } I can't figured out how the problem come from. Any help would be appreciate ! Thanks in advance.

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  • how to read input with multiple lines in java

    - by Gandalf StormCrow
    Hi all, Our professor is making us do some basic programming with java, he gaves a website and everything to register and submit our questions, for today I need to do this one example I feel like I'm on the right track but I just can't figure out the rest .. here is the actualy question : **Sample Input:** 10 12 10 14 100 200 **Sample Output:** 2 4 100 And here is what I've got so far : public class Practice { public static int calculateAnswer(String a, String b) { return (Integer.parseInt(b) - Integer.parseInt(a)); } public static void main(String[] args) { System.out.println(calculateAnswer(args[0], args[1])); } } Now I always get the answer 2 because I'm reading the single line, how can I take all lines into account? thank you For some strange reason everytime I want to execute I get this error: C:\sonic>java Practice.class 10 12 Exception in thread "main" java.lang.NoClassDefFoundError: Fact Caused by: java.lang.ClassNotFoundException: Fact.class at java.net.URLClassLoader$1.run(URLClassLoader.java:20 at java.security.AccessController.doPrivileged(Native M at java.net.URLClassLoader.findClass(URLClassLoader.jav at java.lang.ClassLoader.loadClass(ClassLoader.java:307 at sun.misc.Launcher$AppClassLoader.loadClass(Launcher. at java.lang.ClassLoader.loadClass(ClassLoader.java:248 Could not find the main class: Practice.class. Program will exit. Whosever version of answer I use I get this error, what do I do ? However if I run it in eclipse Run as Run Configuration - Program arguments 10 12 10 14 100 200 I get no output EDIT I have made some progress, at first I was getting the compilation error, then runtime error and now I get wrong answer , so can anybody help me what is wrong with this : import java.io.BufferedReader; import java.io.IOException; import java.io.InputStreamReader; import java.math.BigInteger; public class Practice { public static BigInteger calculateAnswer(String a, String b) { BigInteger ab = new BigInteger(a); BigInteger bc = new BigInteger(b); return bc.subtract(ab); } public static void main(String[] args) throws IOException { BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in)); String line; while ((line = stdin.readLine()) != null && line.length()!= 0) { String[] input = line.split(" "); if (input.length == 2) { System.out.println(calculateAnswer(input[0], input[1])); } } } }

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  • RSA example that do not use NoPadding

    - by Tom Brito
    Where can I find a RSA encrypt example that does not use "NoPadding"? --update Better: how to make this code run correctly without throw the "too much data for RSA block" exception? import java.math.BigInteger; import java.security.KeyFactory; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; /** * Basic RSA example. */ public class TestRSA { public static void main(String[] args) throws Exception { byte[] input = new byte[100]; Cipher cipher = Cipher.getInstance("RSA/None/NoPadding", "BC"); KeyFactory keyFactory = KeyFactory.getInstance("RSA", "BC"); // create the keys RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger("d46f473a2d746537de2056ae3092c451", 16), new BigInteger("11", 16)); RSAPrivateKeySpec privKeySpec = new RSAPrivateKeySpec(new BigInteger( "d46f473a2d746537de2056ae3092c451", 16), new BigInteger("57791d5430d593164082036ad8b29fb1", 16)); RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec); RSAPrivateKey privKey = (RSAPrivateKey) keyFactory.generatePrivate(privKeySpec); // encryption step cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherText = cipher.doFinal(input); // decryption step cipher.init(Cipher.DECRYPT_MODE, privKey); byte[] plainText = cipher.doFinal(cipherText); } }

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  • MySQL JDBC date issues with database server in different timezone

    - by Somatik
    I have a database server in "Europe/London" time zone and my web server in "Europe/Brussels". Since it is summer time now my application server has a 2 hour difference. I created a test to reproduce my issue: Query q = JPA.em().createNativeQuery("SELECT UNIX_TIMESTAMP(startDateTime) FROM `Event` WHERE `id` =574"); BigInteger unix = (BigInteger) q.getSingleResult(); System.out.println(unix + "000 UNIX_TIMESTAMP to BigInteger"); Query q2 = JPA.em().createNativeQuery("SELECT startDateTime FROM `Event` WHERE `id` =574"); Timestamp o = (Timestamp) q2.getSingleResult(); System.out.println(o.getTime() + " Timestamp"); The startDateTime column is defined as 'datetime' (but same issue with 'timestamp') The output I am getting is this: 1340291591000 UNIX_TIMESTAMP to BigInteger 1340284391000 Timestamp Reading java date objects results in a shift in time zone, how do I fix this? I would expect the jdbc driver to just set the "unix time" value it gets from the server in the Date object. (a proper solution should work with any timezone combination, not only for db in GMT)

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  • get greatest prime factor in F#

    - by Alex
    I had VS 11 beta and the following code was working without problem: let rec fac x y = if (x = y) then y elif (x % y = 0I) then fac (x / y) y else fac x / (y + 1I);; Now I installed VS 2012 RC and I get the following error: The type 'System.Numerics.BigInteger -> System.Numerics.BigInteger' is not compatible with the type 'System.Numerics.BigInteger' Is code not correct or F# interactive? It's F# 3.0.

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  • AES code throwing NoSuchPaddingException: Padding NoPaddin unknown

    - by Tom Brito
    The following code is a try to encrypt data using AES with asymmetric key: import java.io.OutputStream; import java.math.BigInteger; import java.security.Key; import java.security.KeyFactory; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import javax.crypto.Cipher; public class AsyncronousKeyTest { private final Cipher cipher; private final KeyFactory keyFactory; private final RSAPrivateKey privKey; private AsyncronousKeyTest() throws Exception { cipher = Cipher.getInstance("AES/CBC/NoPaddin", "BC"); keyFactory = KeyFactory.getInstance("AES", "BC"); // create the keys // TODO should this numbers be random? RSAPrivateKeySpec privKeySpec = new RSAPrivateKeySpec(new BigInteger( "d46f473a2d746537de2056ae3092c451", 16), new BigInteger("57791d5430d593164082036ad8b29fb1", 16)); privKey = (RSAPrivateKey) keyFactory.generatePrivate(privKeySpec); } public void generateAuthorizationAct(OutputStream outputStream) throws Exception { // TODO Ticket #14 - GenerateAuthorization action KeyFactory keyFactory = KeyFactory.getInstance("AES", "BC"); // TODO should this numbers be random? RSAPublicKeySpec pubKeySpec = new RSAPublicKeySpec(new BigInteger("d46f473a2d746537de2056ae3092c451", 16), new BigInteger("11", 16)); RSAPublicKey pubKey = (RSAPublicKey) keyFactory.generatePublic(pubKeySpec); byte[] data = new byte[] {0x01}; byte[] encrypted = encryptAO(pubKey, data); outputStream.write(encrypted); } /** Encrypt the AuthorizationObject. */ public byte[] encryptAO(Key pubKey, byte[] data) throws Exception { cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherText = cipher.doFinal(data); return cipherText; } public byte[] decrypt(byte[] cipherText) throws Exception { cipher.init(Cipher.DECRYPT_MODE, privKey); byte[] decyptedData = cipher.doFinal(cipherText); return decyptedData; } public static void main(String[] args) throws Exception { System.out.println("start"); AsyncronousKeyTest auth = new AsyncronousKeyTest(); auth.generateAuthorizationAct(System.out); System.out.println("done"); } } but at line cipher = Cipher.getInstance(AesEncrypter.getTransformation(), "BC"); it throws NoSuchPaddingException: Padding NoPaddin unknown. What is this? And how to solve?

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  • Java RSA Encrypt using .NET XML Key File - need help

    - by badMonkey
    In .net I have generated the following public key file: <RSAKeyValue> <Modulus>xTSiS4+I/x9awUXcF66Ffw7tracsQfGCn6g6k/hGkLquHYMFTCYk4mOB5NwLwqczwvl8HkQfDShGcvrm47XHKUzA8iadWdA5n4toBECzRxiCWCHm1KEg59LUD3fxTG5ogGiNxDj9wSguCIzFdUxBYq5ot2J4iLgGu0qShml5vwk=</Modulus> <Exponent>AQAB</Exponent> .NET is happy to encrypt using it's normal methods. I am trying to use this key to encode a string in Java and am running into an Arithmetic problem (exception) when I attempt to encrypt the string. The following is the code I am using to encrypt: byte[] modulusBytes = Base64.decode(this.getString(R.string.public_key_modulus)); byte[] exponentBytes = Base64.decode(this.getString(R.string.public_key_exponent)); BigInteger modulus = new BigInteger( modulusBytes ); BigInteger exponent = new BigInteger( exponentBytes); RSAPublicKeySpec rsaPubKey = new RSAPublicKeySpec(modulus, exponent); KeyFactory fact = KeyFactory.getInstance("RSA"); PublicKey pubKey = fact.generatePublic(rsaPubKey); Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherData = cipher.doFinal( new String("big kitty dancing").getBytes() ); It is the final line in the code block that fails. I have looked at numerous examples and this is the best I could come up with. If it is not obvious, the R.string.public_key_modulus is a copy/paste of the text in the Modulus element, same applies for exponent.

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  • Big numbers with fraction support

    - by dutt
    I need a c# number something that can handle very large numbers but also fraction support, I looked at System.Numberics.BigInteger coming in .NET 4.0 but I can't get it to work with fractions. something i = 2; something j = 5; something k = i/j; //should be 0.4 when i tried BigInteger i = 2; BigInteger j = 5; double d = (double)(i/j); //d is 0.0 Does anybody know such a library?

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  • Euler Problem 13

    - by MarkPearl
    The Problem Work out the first ten digits of the sum of the following one-hundred 50-digit numbers. 37107287533902102798797998220837590246510135740250 46376937677490009712648124896970078050417018260538 74324986199524741059474233309513058123726617309629 91942213363574161572522430563301811072406154908250 23067588207539346171171980310421047513778063246676 89261670696623633820136378418383684178734361726757 28112879812849979408065481931592621691275889832738 44274228917432520321923589422876796487670272189318 47451445736001306439091167216856844588711603153276 70386486105843025439939619828917593665686757934951 62176457141856560629502157223196586755079324193331 64906352462741904929101432445813822663347944758178 92575867718337217661963751590579239728245598838407 58203565325359399008402633568948830189458628227828 80181199384826282014278194139940567587151170094390 35398664372827112653829987240784473053190104293586 86515506006295864861532075273371959191420517255829 71693888707715466499115593487603532921714970056938 54370070576826684624621495650076471787294438377604 53282654108756828443191190634694037855217779295145 36123272525000296071075082563815656710885258350721 45876576172410976447339110607218265236877223636045 17423706905851860660448207621209813287860733969412 81142660418086830619328460811191061556940512689692 51934325451728388641918047049293215058642563049483 62467221648435076201727918039944693004732956340691 15732444386908125794514089057706229429197107928209 55037687525678773091862540744969844508330393682126 18336384825330154686196124348767681297534375946515 80386287592878490201521685554828717201219257766954 78182833757993103614740356856449095527097864797581 16726320100436897842553539920931837441497806860984 48403098129077791799088218795327364475675590848030 87086987551392711854517078544161852424320693150332 59959406895756536782107074926966537676326235447210 69793950679652694742597709739166693763042633987085 41052684708299085211399427365734116182760315001271 65378607361501080857009149939512557028198746004375 35829035317434717326932123578154982629742552737307 94953759765105305946966067683156574377167401875275 88902802571733229619176668713819931811048770190271 25267680276078003013678680992525463401061632866526 36270218540497705585629946580636237993140746255962 24074486908231174977792365466257246923322810917141 91430288197103288597806669760892938638285025333403 34413065578016127815921815005561868836468420090470 23053081172816430487623791969842487255036638784583 11487696932154902810424020138335124462181441773470 63783299490636259666498587618221225225512486764533 67720186971698544312419572409913959008952310058822 95548255300263520781532296796249481641953868218774 76085327132285723110424803456124867697064507995236 37774242535411291684276865538926205024910326572967 23701913275725675285653248258265463092207058596522 29798860272258331913126375147341994889534765745501 18495701454879288984856827726077713721403798879715 38298203783031473527721580348144513491373226651381 34829543829199918180278916522431027392251122869539 40957953066405232632538044100059654939159879593635 29746152185502371307642255121183693803580388584903 41698116222072977186158236678424689157993532961922 62467957194401269043877107275048102390895523597457 23189706772547915061505504953922979530901129967519 86188088225875314529584099251203829009407770775672 11306739708304724483816533873502340845647058077308 82959174767140363198008187129011875491310547126581 97623331044818386269515456334926366572897563400500 42846280183517070527831839425882145521227251250327 55121603546981200581762165212827652751691296897789 32238195734329339946437501907836945765883352399886 75506164965184775180738168837861091527357929701337 62177842752192623401942399639168044983993173312731 32924185707147349566916674687634660915035914677504 99518671430235219628894890102423325116913619626622 73267460800591547471830798392868535206946944540724 76841822524674417161514036427982273348055556214818 97142617910342598647204516893989422179826088076852 87783646182799346313767754307809363333018982642090 10848802521674670883215120185883543223812876952786 71329612474782464538636993009049310363619763878039 62184073572399794223406235393808339651327408011116 66627891981488087797941876876144230030984490851411 60661826293682836764744779239180335110989069790714 85786944089552990653640447425576083659976645795096 66024396409905389607120198219976047599490197230297 64913982680032973156037120041377903785566085089252 16730939319872750275468906903707539413042652315011 94809377245048795150954100921645863754710598436791 78639167021187492431995700641917969777599028300699 15368713711936614952811305876380278410754449733078 40789923115535562561142322423255033685442488917353 44889911501440648020369068063960672322193204149535 41503128880339536053299340368006977710650566631954 81234880673210146739058568557934581403627822703280 82616570773948327592232845941706525094512325230608 22918802058777319719839450180888072429661980811197 77158542502016545090413245809786882778948721859617 72107838435069186155435662884062257473692284509516 20849603980134001723930671666823555245252804609722 53503534226472524250874054075591789781264330331690   The Solution private static List<string> table = new List<string> { "37107287533902102798797998220837590246510135740250", "46376937677490009712648124896970078050417018260538", "74324986199524741059474233309513058123726617309629", "91942213363574161572522430563301811072406154908250", "23067588207539346171171980310421047513778063246676", "89261670696623633820136378418383684178734361726757", "28112879812849979408065481931592621691275889832738", "44274228917432520321923589422876796487670272189318", "47451445736001306439091167216856844588711603153276", "70386486105843025439939619828917593665686757934951", "62176457141856560629502157223196586755079324193331", "64906352462741904929101432445813822663347944758178", "92575867718337217661963751590579239728245598838407", "58203565325359399008402633568948830189458628227828", "80181199384826282014278194139940567587151170094390", "35398664372827112653829987240784473053190104293586", "86515506006295864861532075273371959191420517255829", "71693888707715466499115593487603532921714970056938", "54370070576826684624621495650076471787294438377604", "53282654108756828443191190634694037855217779295145", "36123272525000296071075082563815656710885258350721", "45876576172410976447339110607218265236877223636045", "17423706905851860660448207621209813287860733969412", "81142660418086830619328460811191061556940512689692", "51934325451728388641918047049293215058642563049483", "62467221648435076201727918039944693004732956340691", "15732444386908125794514089057706229429197107928209", "55037687525678773091862540744969844508330393682126", "18336384825330154686196124348767681297534375946515", "80386287592878490201521685554828717201219257766954", "78182833757993103614740356856449095527097864797581", "16726320100436897842553539920931837441497806860984", "48403098129077791799088218795327364475675590848030", "87086987551392711854517078544161852424320693150332", "59959406895756536782107074926966537676326235447210", "69793950679652694742597709739166693763042633987085", "41052684708299085211399427365734116182760315001271", "65378607361501080857009149939512557028198746004375", "35829035317434717326932123578154982629742552737307", "94953759765105305946966067683156574377167401875275", "88902802571733229619176668713819931811048770190271", "25267680276078003013678680992525463401061632866526", "36270218540497705585629946580636237993140746255962", "24074486908231174977792365466257246923322810917141", "91430288197103288597806669760892938638285025333403", "34413065578016127815921815005561868836468420090470", "23053081172816430487623791969842487255036638784583", "11487696932154902810424020138335124462181441773470", "63783299490636259666498587618221225225512486764533", "67720186971698544312419572409913959008952310058822", "95548255300263520781532296796249481641953868218774", "76085327132285723110424803456124867697064507995236", "37774242535411291684276865538926205024910326572967", "23701913275725675285653248258265463092207058596522", "29798860272258331913126375147341994889534765745501", "18495701454879288984856827726077713721403798879715", "38298203783031473527721580348144513491373226651381", "34829543829199918180278916522431027392251122869539", "40957953066405232632538044100059654939159879593635", "29746152185502371307642255121183693803580388584903", "41698116222072977186158236678424689157993532961922", "62467957194401269043877107275048102390895523597457", "23189706772547915061505504953922979530901129967519", "86188088225875314529584099251203829009407770775672", "11306739708304724483816533873502340845647058077308", "82959174767140363198008187129011875491310547126581", "97623331044818386269515456334926366572897563400500", "42846280183517070527831839425882145521227251250327", "55121603546981200581762165212827652751691296897789", "32238195734329339946437501907836945765883352399886", "75506164965184775180738168837861091527357929701337", "62177842752192623401942399639168044983993173312731", "32924185707147349566916674687634660915035914677504", "99518671430235219628894890102423325116913619626622", "73267460800591547471830798392868535206946944540724", "76841822524674417161514036427982273348055556214818", "97142617910342598647204516893989422179826088076852", "87783646182799346313767754307809363333018982642090", "10848802521674670883215120185883543223812876952786", "71329612474782464538636993009049310363619763878039", "62184073572399794223406235393808339651327408011116", "66627891981488087797941876876144230030984490851411", "60661826293682836764744779239180335110989069790714", "85786944089552990653640447425576083659976645795096", "66024396409905389607120198219976047599490197230297", "64913982680032973156037120041377903785566085089252", "16730939319872750275468906903707539413042652315011", "94809377245048795150954100921645863754710598436791", "78639167021187492431995700641917969777599028300699", "15368713711936614952811305876380278410754449733078", "40789923115535562561142322423255033685442488917353", "44889911501440648020369068063960672322193204149535", "41503128880339536053299340368006977710650566631954", "81234880673210146739058568557934581403627822703280", "82616570773948327592232845941706525094512325230608", "22918802058777319719839450180888072429661980811197", "77158542502016545090413245809786882778948721859617", "72107838435069186155435662884062257473692284509516", "20849603980134001723930671666823555245252804609722", "53503534226472524250874054075591789781264330331690"}; static void Main(string[] args) { BigInteger result = 0; table.ForEach(x => result += BigInteger.Parse(x)); Console.WriteLine(result.ToString().Substring(0,10)); Console.ReadLine(); }

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  • Converting a byte array to a X.509 certificate

    - by ddd
    I'm trying to port a piece of Java code into .NET that takes a Base64 encoded string, converts it to a byte array, and then uses it to make a X.509 certificate to get the modulus & exponent for RSA encryption. This is the Java code I'm trying to convert: byte[] externalPublicKey = Base64.decode("base 64 encoded string"); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); EncodedKeySpec publicKeySpec = new X509EncodedKeySpec(externalPublicKey); Key publicKey = keyFactory.generatePublic(publicKeySpec); RSAPublicKey pbrtk = (java.security.interfaces.RSAPublicKey) publicKey; BigInteger modulus = pbrtk.getModulus(); BigInteger pubExp = pbrtk.getPublicExponent(); I've been trying to figure out the best way to convert this into .NET. So far, I've come up with this: byte[] bytes = Convert.FromBase64String("base 64 encoded string"); X509Certificate2 x509 = new X509Certificate2(bytes); RSA rsa = (RSA)x509.PrivateKey; RSAParameters rsaParams = rsa.ExportParameters(false); byte[] modulus = rsaParams.Modulus; byte[] exponent = rsaParams.Exponent; Which to me looks like it should work, but it throws an exception when I use the base 64 encoded string from the Java code to generate the X509 certificate. Is Java's X.509 implementation just incompatible with .NET's, or am I doing something wrong in my conversion from Java to .NET? Or is there simply no conversion from Java to .NET in this case?

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  • SQLAlchemy DetachedInstanceError with regular attribute (not a relation)

    - by haridsv
    I just started using SQLAlchemy and get a DetachedInstanceError and can't find much information on this anywhere. I am using the instance outside a session, so it is natural that SQLAlchemy is unable to load any relations if they are not already loaded, however, the attribute I am accessing is not a relation, in fact this object has no relations at all. I found solutions such as eager loading, but I can't apply to this because this is not a relation. I even tried "touching" this attribute before closing the session, but it still doesn't prevent the exception. What could be causing this exception for a non-relational property even after it has been successfully accessed once before? Any help in debugging this issue is appreciated. I will meanwhile try to get a reproducible stand-alone scenario and update here. Update: This is the actual exception message with a few stacks: File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 159, in __get__ return self.impl.get(instance_state(instance), instance_dict(instance)) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/attributes.py", line 377, in get value = callable_(passive=passive) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/state.py", line 280, in __call__ self.manager.deferred_scalar_loader(self, toload) File "/home/hari/bin/lib/python2.6/site-packages/SQLAlchemy-0.6.1-py2.6.egg/sqlalchemy/orm/mapper.py", line 2323, in _load_scalar_attributes (state_str(state))) DetachedInstanceError: Instance <ReportingJob at 0xa41cd8c> is not bound to a Session; attribute refresh operation cannot proceed The partial model looks like this: metadata = MetaData() ModelBase = declarative_base(metadata=metadata) class ReportingJob(ModelBase): __tablename__ = 'reporting_job' job_id = Column(BigInteger, Sequence('job_id_sequence'), primary_key=True) client_id = Column(BigInteger, nullable=True) And the field client_id is what is causing this exception with a usage like the below: Query: jobs = session \ .query(ReportingJob) \ .filter(ReportingJob.job_id == job_id) \ .all() if jobs: # FIXME(Hari): Workaround for the attribute getting lazy-loaded. jobs[0].client_id return jobs[0] This is what triggers the exception later out of the session scope: msg = msg + ", client_id: %s" % job.client_id

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  • How would you handle making an array or list that would have more entries than the standard implemen

    - by faceless1_14
    I am trying to create an array or list that could handle in theory, given adequate hardware and such, as many as 100^100 BigInteger entries. The problem with using an array or standard list is that they can only hold Integer.MAX_VALUE number of entries. How would you work around this limitations? A whole new class/interface? A wrapper for list? another data type entirely?

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  • What types of programming contest problems are there?

    - by Alex
    Basically, I want to make a great reference for use with programming contests that would have all of the algorithms that I can put together that I would need during a contest as well as sample useage for the code. I'm planning on making this into a sort of book that I could print off and take with me to competitions. I would like to do this rather than simply bringing other books (such as Algorithms books) because I think that I will learn a lot more by going over all of the algorithms myself as well as I would know exactly what I have in the book, making it more efficient to have and use. So, I've been doing research to determine what types of programming problems and algorithms are common on contests, and the only thing I can really find is this (which I have seen referenced a few times): Hal Burch conducted an analysis over spring break of 1999 and made an amazing discovery: there are only 16 types of programming contest problems! Furthermore, the top several comprise almost 80% of the problems seen at the IOI. Here they are: Dynamic Programming Greedy Complete Search Flood Fill Shortest Path Recursive Search Techniques Minimum Spanning Tree Knapsack Computational Geometry Network Flow Eulerian Path Two-Dimensional Convex Hull BigNums Heuristic Search Approximate Search Ad Hoc Problems The most challenging problems are Combination Problems which involve a loop (combinations, subsets, etc.) around one of the above algorithms - or even a loop of one algorithm with another inside it. These seem extraordinarily tricky to get right, even though conceptually they are ``obvious''. Now that's good and all, but that study was conducted in 1999, which was 13 years ago! One thing I know is that there are no BigNums problems any more (as Java has a BigInteger class, they have stopped making those problems). So, I'm wondering if anyone knows of any more recent studies of the types of problems that may be seen in a programming contest? Or what the most helpful algorithms on contests would be?

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  • Is generic Money<T_amount> a good idea?

    - by jdk
    I have a Money Type that allows math operations and is sensitive to exchange rates so it will reduce one currency to another if rate is available to calculate in a given currency, rounds by various methods. It has other features that are sensitive to money, but I need to ask if the basic data type used should be made generic in nature. I've realized that the basic data type to hold an amount may differ for financial situations, for example: retail money might be expressed as all cents using int or long where fractions of cents do not matter, decimal is commonly used for its fixed behaviour, sometimes double seems to be used for big finance and large values sometimes a special BigInteger or 3rd-party type is used. I want to know if it would be considered good form to turn Money into Money<T_amount> so it can be used in any one of the above chosen scenarios?

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  • Why is Java not telling me when I can't use Integer?

    - by Sebi
    For a small project (Problem 10 Project Euler) i tried to sum up all prime numbers below 2 millions. So I used a brute force method and iterated from 0 to 2'000'000 and checked if the number is a prime. If it is I added it to the sum: private int sum = 0; private void calculate() { for (int i = 0; i < 2000000; i++) { if (i.isPrime()) { sum = sum + i; } } sysout(sum) } The result of this calculation is 1179908154, but this is incorrect. So i changed int to BigInteger and now i get the correct sum 142913828922. Obviously the range of int was overflowed. But why can't Java tell my that? (e.g. by an exception)

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  • Convert an array of bytes into one decimal number as a string

    - by Martin Kirsche
    I'm trying to write function that converts an arbitrary large array of bytes (larger than 64-bit) into a decimal number represented as string in c# and I simply can't figure out how to do it. For example the following code ... Console.WriteLine(ConvertToString( new byte[] { 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 0x00 })); .. should print out 22774453838368691933757882222884355840 I don't want to just use an extra library like biginteger for that, because I want it to be simple and like to understand how it works.

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  • Spring MVC configuration problems

    - by Smek
    i have some problems with configuring Spring MVC. I made a maven multi module project with the following modules: /api /domain /repositories /webapp I like to share the domain and the repositories between the api and the webapp (both web projects). First i want to configure the webapp to use the repositories module so i added the dependencies in the xml file like this: <dependency> <groupId>${project.groupId}</groupId> <artifactId>domain</artifactId> <version>1.0-SNAPSHOT</version> </dependency> <dependency> <groupId>${project.groupId}</groupId> <artifactId>repositories</artifactId> <version>1.0-SNAPSHOT</version> </dependency> And my controller in the webapp module looks like this: package com.mywebapp.webapp; import com.mywebapp.domain.Person; import com.mywebapp.repositories.services.PersonService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.Configuration; import org.springframework.stereotype.Controller; import org.springframework.ui.ModelMap; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RequestMethod; @Controller @RequestMapping("/") @Configuration @ComponentScan("com.mywebapp.repositories") public class PersonController { @Autowired PersonService personservice; @RequestMapping(method = RequestMethod.GET) public String printWelcome(ModelMap model) { Person p = new Person(); p.age = 23; p.firstName = "John"; p.lastName = "Doe"; personservice.createNewPerson(p); model.addAttribute("message", "Hello world!"); return "index"; } } In my webapp module i try to load configuration files in my web.xml like this: <context-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:/META-INF/persistence-context.xml, classpath:/META-INF/service-context.xml</param-value> </context-param> These files cannot be found so i get the following error: org.springframework.beans.factory.BeanDefinitionStoreException: IOException parsing XML document from class path resource [META-INF/persistence-context.xml]; nested exception is java.io.FileNotFoundException: class path resource [META-INF/persistence-context.xml] cannot be opened because it does not exist These files are in the repositories module so my first question is how can i make Spring to find these files? I also have trouble Autowiring the PersonService to my Controller class did i forget to configure something in my XML? Here is the error message: [INFO] [talledLocalContainer] SEVERE: Exception sending context initialized event to listener instance of class org.springframework.web.context.ContextLoaderListener [INFO] [talledLocalContainer] org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'personServiceImpl': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.mywebapp.repositories.repository.PersonRepository com.mywebapp.repositories.services.PersonServiceImpl.personRepository; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No matching bean of type [com.mywebapp.repositories.repository.PersonRepository] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)} PersonServiceImple.java: package com.mywebapp.repositories.services; import com.mywebapp.domain.Person; import com.mywebapp.repositories.repository.PersonRepository; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.mongodb.core.MongoTemplate; import org.springframework.stereotype.Service; @Service public class PersonServiceImpl implements PersonService{ @Autowired public PersonRepository personRepository; @Autowired public MongoTemplate personTemplate; @Override public Person createNewPerson(Person person) { return personRepository.save(person); } } PersonService.java package com.mywebapp.repositories.services; import com.mywebapp.domain.Person; public interface PersonService { Person createNewPerson(Person person); } PersonRepository.java: package com.mywebapp.repositories.repository; import com.mywebapp.domain.Person; import org.springframework.data.mongodb.repository.MongoRepository; import org.springframework.stereotype.Repository; import java.math.BigInteger; @Repository public interface PersonRepository extends MongoRepository<Person, BigInteger> { } persistance-context.xml <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xmlns:mongo="http://www.springframework.org/schema/data/mongo" xsi:schemaLocation= "http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd http://www.springframework.org/schema/data/mongo http://www.springframework.org/schema/data/mongo/spring-mongo-1.0.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd"> <context:property-placeholder location="classpath:mongo.properties"/> <mongo:mongo host="${mongo.host}" port="${mongo.port}" id="mongo"> <mongo:options connections-per-host="${mongo.connectionsPerHost}" threads-allowed-to-block-for-connection-multiplier="${mongo.threadsAllowedToBlockForConnectionMultiplier}" connect-timeout="${mongo.connectTimeout}" max-wait-time="${mongo.maxWaitTime}" auto-connect-retry="${mongo.autoConnectRetry}" socket-keep-alive="${mongo.socketKeepAlive}" socket-timeout="${mongo.socketTimeout}" slave-ok="${mongo.slaveOk}" write-number="1" write-timeout="0" write-fsync="true"/> </mongo:mongo> <mongo:db-factory dbname="person" mongo-ref="mongo" id="mongoDbFactory"/> <bean id="personTemplate" name="personTemplate" class="org.springframework.data.mongodb.core.MongoTemplate"> <constructor-arg name="mongoDbFactory" ref="mongoDbFactory"/> </bean> <mongo:repositories base-package="com.mywebapp.repositories.repository" mongo-template-ref="personTemplate"> <mongo:repository id="personRepository" repository-impl-postfix="PersonRepository" mongo-template-ref="personTemplate" create-query-indexes="true"/> </mongo:repositories> Thanks

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  • Is generic Money<TAmount> a good implementation idea?

    - by jdk
    I have a Money Type that allows math operations and is sensitive to exchange rates so it will reduce one currency to another if rate is available to calculate in a given currency, rounds by various methods. It has other features that are sensitive to money, but I need to ask if the basic data type used should be made generic in nature. I've realized that the basic data type to hold an amount may differ for financial situations, for example: retail money might be expressed as all cents using int or long where fractions of cents do not matter, decimal is commonly used for its fixed behaviour, sometimes double seems to be used for big finance and large values sometimes a special BigInteger or 3rd-party type is used. I want to know if it would be considered good form to turn Money into Money<T_amount> so it can be used in any one of the above chosen scenarios?

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  • Cascading updates with business key equality: Hibernate best practices?

    - by Traphicone
    I'm new to Hibernate, and while there are literally tons of examples to look at, there seems to be so much flexibility here that it's sometimes very hard to narrow all the options down the best way of doing things. I've been working on a project for a little while now, and despite reading through a lot of books, articles, and forums, I'm still left with a bit of a head scratcher. Any veteran advice would be very appreciated. So, I have a model involving two classes with a one-to-many relationship from parent to child. Each class has a surrogate primary key and a uniquely constrained composite business key. <class name="Container"> <id name="id" type="java.lang.Long"> <generator class="identity"/> </id> <properties name="containerBusinessKey" unique="true" update="false"> <property name="name" not-null="true"/> <property name="owner" not-null="true"/> </properties> <set name="items" inverse="true" cascade="all-delete-orphan"> <key column="container" not-null="true"/> <one-to-many class="Item"/> </set> </class> <class name="Item"> <id name="id" type="java.lang.Long"> <generator class="identity"/> </id> <properties name="itemBusinessKey" unique="true" update="false"> <property name="type" not-null="true"/> <property name="color" not-null="true"/> </properties> <many-to-one name="container" not-null="true" update="false" class="Container"/> </class> The beans behind these mappings are as boring as you can possibly imagine--nothing fancy going on. With that in mind, consider the following code: Container c = new Container("Things", "Me"); c.addItem(new Item("String", "Blue")); c.addItem(new Item("Wax", "Red")); Transaction t = session.beginTransaction(); session.saveOrUpdate(c); t.commit(); Everything works fine the first time, and both the Container and its Items are persisted. If the above code block is executed again, however, Hibernate throws a ConstraintViolationException--duplicate values for the "name" and "owner" columns. Because the new Container instance has a null identifier, Hibernate assumes it is an unsaved transient instance. This is expected but not desired. Since the persistent and transient Container objects have the same business key values, what we really want is to issue an update. It is easy enough to convince Hibernate that our new Container instance is the same as our old one. With a quick query we can get the identifier of the Container we'd like to update, and set our transient object's identifier to match. Container c = new Container("Things", "Me"); c.addItem(new Item("String", "Blue")); c.addItem(new Item("Wax", "Red")); Query query = session.createSQLQuery("SELECT id FROM Container" + "WHERE name = ? AND owner = ?"); query.setString(0, c.getName()); query.setString(1, c.getOwner()); BigInteger id = (BigInteger)query.uniqueResult(); if (id != null) { c.setId(id.longValue()); } Transaction t = session.beginTransaction(); session.saveOrUpdate(c); t.commit(); This almost satisfies Hibernate, but because the one-to-many relationship from Container to Item cascades, the same ConstraintViolationException is also thrown for the child Item objects. My question is: what is the best practice in this situation? It is highly recommended to use surrogate primary keys, and it is also recommended to use business key equality. When you put these two recommendations in to practice together, however, two of the greatest conveniences of Hibernate--saveOrUpdate and cascading operations--seem to be rendered almost completely useless. As I see it, I have only two options: Manually fetch and set the identifier for each object in the mapping. This clearly works, but for even a moderately sized schema this is a lot of extra work which it seems Hibernate could easily be doing. Write a custom interceptor to fetch and set object identifiers on each operation. This looks cleaner than the first option but is rather heavy-handed, and it seems wrong to me that you should be expected to write a plug-in which overrides Hibernate's default behavior for a mapping which follows the recommended design. Is there a better way? Am I making completely the wrong assumptions? I'm hoping that I'm just missing something. Thanks.

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  • Linear Recurrence for very large n

    - by Android Decoded
    I was trying to solve this problem on SPOJ (http://www.spoj.pl/problems/REC/) F(n) = a*F(n-1) + b where we have to find F(n) Mod (m) where 0 <= a, b, n <= 10^100 1 <= M <= 100000 I am trying to solve it with BigInteger in JAVA but if I run a loop from 0 to n its getting TLE. How could I solve this problem? Can anyone give some hint? Don't post the solution. I want hint on how to solve it efficiently.

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  • Convert a string representation of a hex dump to a byte array using Java?

    - by ravigad
    I am looking for a way to convert a long string (from a dump), that represents hex values into a byte array. I couldn't have phrased it better than the person that posted the same question here: http://www.experts-exchange.com/Programming/Programming_Languages/Java/Q_21062554.html But to keep it original, I'll phrase it my own way: suppose I have a string "00A0BF" that I would like interpreted as the byte[] {0x00,0xA0,0xBf} what should I do? I am a Java novice and ended up using BigInteger and watching out for leading hex zeros. But I think it is ugly and I am sure I am missing something simple...

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