java,methods,finalRelated issues-Collection of common programming errors
Preetygeek
java c++ winforms jni
So, i have visual studio consloe project that compile to .dll file. I’ve created simple windows form System::Windows::Forms::FormI’ve created a .java file:import java.io.Serializable;public class MyBean implements Serializable{/*** */static{System.loadLibrary(“MyBean”); }private static final long serialVersionUID = 1L;private static native String getDateCpp();public String getDate(){return getDateCpp();}}compiled it and generate a .h file by javah:/* DO NOT EDIT THIS FILE – it is machine genera
Felix
java javassist
With Javassist, is there any way to inject code into a native method? In this case, I’m trying to make the OpenGL calls in my game print out their names and values when called, but all my attempts have hit errors when I assume the openGL dll code is added.The method would look something like:public static native void glEnable(int paramInt);Since the methods initially have no body, the only way I’ve found to actually add the code is with something like:CtBehavior method = cl.getDeclaredBehaviors(
Can Eldem
java eclipse leap-motion
I have a project that uses leap motion sdk. I wrote this project in Eclipse. When I run my program I don’t have any problem because I set my native libraries as it is suggested from configuration. However, when I export my application I can not run my program because Eclipse does not include my native libraries and I am having this error. Native code library failed to load. java.lang.UnsatisfiedLinkError: no LeapJava in java.library.pathMy purpose is create a .jar file which user can run with o
Arturs
java android upnp
From Android 4.1 (under Wi-Fi Direct service discovery) it is suppose to support native UPnP service discovery.I presume it was developed for Wi-Fi Direct, but the methods available seem to be generic. Even the JavaDoc for methods mention that it searches for all UPnP services on the network and not only WiFi Direct slaves/masters.However, I am failing to implement it so that it works… I manage to set up all requirements and I get positive onSuccess callbacks, but I receive no onUpnpServiceAva
TheEnemyOfQuality
java dll linker jni
I’ve got a bit of an odd problem. I have a project in C++ that’s basically a wrapper for a third party DLL like this:MyLibrary –loads DLL_A —-loads DLL_BI load DLL_A with LoadLibrary(), wrap several of its functions and generate my own DLL. I’ve tested this in a C++ project and a C# project. Both do everything they’re supposed to do: load DLL_A, make a couple of function calls, and indirectly load DLL_B. The problem is when I build a DLL for java and make the calls through JNI. Everything run
user614454
java android https
I am trying to make a HTTPS call using Java to a browser that uses the native login prompt.http://blog.stevensanderson.com/2008/08/25/using-the-browsers-native-login-prompt/Currently I’m using the below for HTTP and it works fine for other websites since I know the parameters to put in…however it fails for the above type of login (I am not sure how to capture the parameters…it’s a login pop up..or if this is even the correct approach)….any ideas??..thanksHttpUtility.sendPostRequest(request
Karel Petranek
java java-web-start java-native-interface
I am using Java Web Start to launch a Java application that depends on some third party native libraries. These native libraries then subsequently load another native library (commonLib) as their dependency using LoadLibrary/dlopen.When not using Web Start, everything works as expected when the native libraries are located in the same directory.Web Start, however, requires the native libraries to be packed in a jar file and referenced in the jnlp file, which I did:<!– Windows OS –><re
MvG
lion java 32-bit
MotivationI have a proprietary java application which used to work under Snow Leopard but fails under Lion with the following backtrace:Exception in thread “AWT-EventQueue-0” java.lang.IllegalArgumentException: Invalid display modeat apple.awt.CGraphicsDevice.setDisplayMode(CGraphicsDevice.java:472)at apple.awt.CGraphicsDevice.setFullScreenWindowSynchronized(CGraphicsDevice.java:363)at apple.awt.CGraphicsDevice.access$000(CGraphicsDevice.java:25)at apple.awt.CGraphicsDevice$1SetFullScreenAction.
Arne
java sql hibernate hsqldb
I use HSQLDB and Hibernate. I have to implement some functionality on database level (trigger …) and because of this I have to execute some native SQL. I create a new table (works) and then try to insert some data (fails). I do this as SA such there should be no access right violation. Someone can guess why the user lacks privilege or object not found: A492Interface is thrown?This is my code (simplified):session.createSQLQuery(“CREATE TABLE entity_table_map (entity_name VARCHAR(50) NOT NULL PR
user3299028
java hadoop native-code
I am having issues while running job with large data (~15G) on hadoop cluster using SimString Native library. However job runs fine on medium/small dataset(~200M). During the job SimString first create a file based database for matching strings and then perform matching on a given String against strings in database. After job is completed it deletes the file-based database. The job runs in a multi-threaded(100 threads) fashion.Around 22 mappers are created for job execution, each running 100 thr
bjsn
c++ interface methods virtual
I read different opinions about this question. Let’s say I have an interface class with a bunch of pure virtual methods. I implement those methods in a class that implements the interface and I do not expect to derive from the implementation.Is there a need for declaring the methods in the implementation as virtual as well? If yes, why?
Brian
java methods parameters arguments return
I’m trying to understand passing arguments and I’ve run into an issue.Let’s say I have the following code:I pass the value 60 to the method someMethod. From there I want that value to be modified with a user input. Once it gets modified, I want it pass that value to another method called getValue. The getValue method then returns that value.Here’s the problem:1) If I were to call someMethod, it would also call for the user input again which I don’t want.2) What is the correct way of printing out
Groo
c# methods method-hiding
Per MSDN, the “new” keyword when used for method hiding only suppresses a warning. http://msdn.microsoft.com/en-us/library/435f1dw2.aspxDo I really need this “new” keyword to perform method hiding? If I have a child class that has the same method name but doesn’t explicitly state that it is overriding, isn’t that the same thing essentially, I just get a warning? Please tell me if my understanding is correct. Thanks
tr9sh
c# methods namespaces field
I am trying to create an application that deletes user documents at start-up (I am aware that this may sound malicious but it is for a school project).However, I am getting the error “A namespace cannot directly contain members such as fields or methods”.Looking over it, it seems fine? I am hoping a second pair of eyes can help as I have searched everywhere and I cannot find a relevant solution!Admittedly, because of my very basic knowledge, I have used a lot of help online and from books and wh
John Kugelman
java class methods constructor
I’m a student. Just got back a homework assignment stating I should call the constructor method rather than reusing the same code. I copied the code because I could not call the constructor without an error. What is the proper syntax to call the constructor method…from a separate method?I did do a search, but I could not find this specific (within the class) issue. I did try using “this” as well as creating a class instance too, but I keep getting errors.import java.util.Random; public class C
aioobe
java methods deprecated
I am using eclipse to develop a web application. Just today I have updated my struts version by changing the JAR file. I am getting warnings at some places that methods are deprecated, but the code is working fine.I want to know some thingsIs it wrong to use Deprecated methods or classes in Java? What if I don’t change any method and run my application with warnings that I have, will it create any performance issue.
Brandon Miller
c++ oop templates methods implementation
I am aware that the syntax for declaring a template class method in a header and defining it in a source file goes as so:myclass.htemplate <typename T> class MyClass {public:void method(T input);private:T privVar; };myclass.cpptemplate <typename T> void MyClass<T>::method(T input) {privVar = input; }But, what if the method is also a template? I have am adding methods to the basic_string class, and I want to know how to write the implementation for the functions.MyString.htempla
Silver Quettier
java exception methods
Context:I have an abstract class SuperClass, which has a substantial number of subclasses, each working on a different business object, but in similar fashion.I need to add some new functionality which definitely has its place in SuperClass, but will rely on a subclass-specific attribute, that I need to get in the superclass method. The obvious way here is to add an abstract getter in SuperClass for the attribute, and have every subclass override it so that it can send the correct attribute when
Alex
ruby-on-rails methods routes
I have just started using Rails and I am trying to build a banking app. I am having trouble setting up transactions between accounts. I have currently scaffolded Transaction and Account. In my transaction page I can create a list of transaction with each transaction containing information about the source account, amount to transfer and the destination account. However, at the end of the page I would like a link or a button that processes all the transactions on the page and clears the page. T
Tshepang
java methods compiler
I’ve never had this issue and since there are no errors given, I am unsure of where to even look. I’ve had a heck of a time with this program (it is my first time doing methods). Prior to this issue, it kept throwing exceptions. While I researched that piece, and managed to fix the error, I get the feeling it isn’t right. Please let me know if the entire code is off (preferably some constructive criticism) or if I’m close:import java.io.*;public class InsuranceMethod2//class name here, same
ChssPly76
java reflection final
Let’s start with a simple test case:import java.lang.reflect.Field;public class Test {private final int primitiveInt = 42;private final Integer wrappedInt = 42;private final String stringValue = “42”;public int getPrimitiveInt() { return this.primitiveInt; }public int getWrappedInt() { return this.wrappedInt; }public String getStringValue() { return this.stringValue; }public void changeField(String name, Object value) throws IllegalAccessException, NoSuchFieldException {Field field = Test.
Rob Kielty
Peter Lawrey
java performance static final initializer
Before I ask my question can I please ask not to get a lecture about optimising for no reason. Consider the following questions purely academic.I’ve been thinking about the efficiency of accesses between root (ie often used and often accessing each other) classes in Java, but this applies to most OO languages/compilers. The fastest way (I’m guessing) that you could access something in Java would be a static final reference. Theoretically, since that reference is available during loading, a good
Dimitri Dewaele
logging static logback final
Should I use a static final or static logger?private static final Logger logger = LoggerFactory.getLogger(MyClass.class);versusprivate static Logger logger = LoggerFactory.getLogger(MyClass.class);Remark: a simular question is available, but only discusses the static part.
romaintaz
java final ternary-operator
Consider this code snippet:public static void main(String[] args) {int z1 = 0;final int z2 = 0;System.out.println(false ? z1 : ‘X’);System.out.println(false ? z2 : ‘X’); }When running this code, I would expect to see two X in your console. However, the real output is:88XIf we take a look at the Java specifications regarding the ternary operator, we found thatIf one of the operands is of type T where T is byte, short, or char, and the other operand is a constant expression of type int whose value
tbroberg
java static final
I’m seeing some very strange behavior in a java program. The failure is not reproducible, so all I have to go on is the original logs.The class looks something like this:public class MyClass {public static final String MY_CONSTANT_STRING = “This should never change”;public boolean checkEndsWithCS(String inString) {return inString.endsWith(MY_CONSTANT_STRING);}public String getString() {return “Some text ‘” + MY_CONSTANT_STRING + “‘ some more text”;} }In the logs, I see a case where getString ret
Without Me It Just Aweso
java static compilation final
In java, say I have the following==fileA.java== class A { public static final int SIZE = 100; } Then in another file i use this value==fileB.java== import A; class b {Object[] temp = new Object[A.SIZE]; }When this gets compiled does SIZE get replaced with the value 100, so that if i were to down the road replace the FileA.jar but not FileB.jar would the object array get the new value or would it have been hardcoded to 100 because thats the value when it was originally built?Thanks, Stephanie
Andres
java security final
While there are many reasons to use the ‘final’ keyword in Java, one of the ones I keep hearing over and over again is that it makes your code more secure. While this seems to make sense in this trivial case:public class Password {public final String passwordHash;… }With the final keyword, you would expect that no malicious code would be able to change the variable passwordHash. However, using reflection it is possible to change the final modifier on the passwordHash field. So does ‘final’ pro
om-nom-nom
java static attributes private final
In java, what’s the difference between:private final static int NUMBER = 10;Andprivate final int NUMBER = 10;Both are private and both are final, the difference is the static attribute.What’s better to use? And why?
Goran Martinic
java garbage-collection final
Today my colleagues and me have a discussion about the usage of the final keyword in Java to improve the garbage collection.For example, if you write a method like:public Double doCalc(final Double value) {final Double maxWeight = 1000.0;final Double totalWeight = maxWeight * value;return totalWeight; }Declaring the variables in the method final would help the garbage collection to clean up the memory from the unused variables in the method after the method exits.Is this true?
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