I have an object profileModel in my profile package and my profile.scala.html file have following code
#(model: ProfileModel)
when I compiles, it is giving an error recursive value model needs type
But when I moved this class to models with my application.conf as
ebean.default="models.*"
it works.
My guess is scala compiler automatically adds models.* to class path at the time of compilation
Is there a way to make this work without moving the class back to models package ?
I am using play 2.2.1 built with Scala 2.10.2
If I understand you right, if your ProfileModel exists in profile package correct declaration in the view should be:
#(myProfile: profile.ProfileModel)
And 'yes', Play imports automatically all models and controllers (and also other well known types), but if you want to use any type in custom package (or ie. imported lib) you need to use full qualified path to it.
Related
In my Android Application I have an annotation processor which generates files using JavaPoet and places them under the package generated.schema.
The files are generating correctly. Whenever I use the generated file like so
GeneratedFile.someGeneratedMethod();
I get the following error:
error: package generated.schema does not exist.
But if I include the fully qualified class name instead of importing like so
generated.schema.GeneratedFile.someGeneratedMethod();
the code compiles and runs without any error.
I don't want to add complete package each time I am using GeneratedFile. I'm not sure what I did wrong, since I'm still learning to work with Annotation Processor.
Files generated by other libraries including Realm, DataBinding are all working correctly as expected.
File Generation :
using JavaPoet I run the following code.
if (roundEnvironment.processingOver()) {
for (TypeElement element : apiList) {
TypeSpec clazz = generateFile(element);
JavaFile.builder(NamespaceCreator.generateClassPackage(element), clazz)
.build()
.writeTo(filer);
}
}
NamespaceCreator.generateClassPackage(element) returns the package name for class i.e generated.schema.
While generating classes I was waiting for the last processing pass. the code generation encapsulated by
if (roundEnvironment.processingOver())
I was getting a warning because of this:
File for type 'generated.schema.GeneratedFile' created in the last round will not be subject to annotation processing.
I was aware of this warning before I posted the question, however I was willing to ignore further annotation processing on my generated files for simplicity of generating all files in one go.
Even though, after removing the last round/pass check from file generation I can correctly (with import) access the generated files without any error; I still don't understand how generating files throughout all rounds affects accessing files during build with import.
For that I will be posting a new question.
I would like to reference a class Bag in a JAR file, but Eclipse is telling me that Bag cannot be resolved to a type. I have added the JAR in which Bag is defined to the classpath for the project, but the error is still there. What am I doing wrong?
I think you can't do that, because the Bag class in algs4.jar is inside the default package.
Before J2SE 1.4, we still can import classes from the default package using a syntax like this:
import Unfinished;
But from J2SE 1.5, that's no longer allowed. So if we want to access a default package class from within a packaged class requires moving the default package class into a package of its own. Read here for more detail explanation :
How to access java-classes in the default-package?
Some options you can choose :
Access the class via reflection or some other indirect method. But it is a little bit hard, something like this :
Class fooClass = Class.forName("FooBar");
Method fooMethod = fooClass.getMethod("fooMethod", new Class[] { String.class });
String fooReturned = fooMethod.invoke(fooClass.newInstance(), new String("I did it"));
If you own the source code of that jar library, you need to put it in properly package and wrap it again as a new jar library.
You may need to either fully qualify the Bag class, or import it.
So I have two Jars I want to use in my project from here http://www.jhlabs.com/ip/filters/index.html
I added both CheckFilter and MarbleFilter to my class path. But when I do
CheckFilter();
It says I have to create a method CheckFilter()
I'm pretty sure that's the method I need to call to use that effect. But when I try any of the other methods in the library Jar it still gives me the same thing.
I have no experience with importing/using external libraries. Any help would be great.
checkFilter = new CheckFilter();
CheckFilter();
I tried above and it says I need to create a local variable checkFilter
How are you writing up the code. I will suggest to use eclipse IDE, it will make your tasks simple
If you are using eclipse. You need to do import the jar Filters.jar to your build path
which as you mentioned you downloaded from JHLabs Download page
I found Filters.jar inside dist directory.
Then you will be able to import the class or package
import com.jhlabs.image.*;
OR
import com.jhlabs.image.CheckFilter;
After importing the class or package you will be able to create object to it by
CheckFilter checkFilter = new CheckFilter();
In case you are totally new you can take help from people over IRC or chat and get going.
Someone would be able to quickly help you out
----==----==----==----==----==----==----==----==----
Read your comments and Question again.
You are totally missing the point. If you call to CheckFilter() directly without invoking new keyword, compiler will consider you are trying to access a method which is inside the class you are writing up. and give you error.
As I mentioned above. Your are trying to accessing Instance variable for the class without declaring it. Either do
CheckFilter checkFilter;
before you access checkFilter variable or directly instantiate the class the way I mentioned.
Seems to me you are missing a log of points :D
Methods don't exist without a class. That is probably the constructor to a class. Use
CheckFilter checkFilter = new CheckFilter();
instead. Then call methods on checkFilter.
From #andy-thomas in this similar question
The import statement imports classes from the jar file, not the jar file itself.
An import statement of the form:
import stdlib.*;
will import all the classes in the package stdlib.
Oracle provides this tutorial on importing.
This statement
CheckFilter();
Tries to call a method CheckFilter defined in your class, which is not the case. If this is a utility function, this may be a static method, in which case you can call it like this
ClassName.CheckFilter(); // replace ClassName with the class containing this function
If not, then you may have to instantiate an object
ClassName obj = new ClassName();
obj.CheckFilter();
or skip the object variable
new ClassName().CheckFilter(); // Not prefered
To add jar files, right click on your project in "Package Explorer", go to "Configure Build Path" and then to "Add External Jars".
Set the jar (libraries) into your classpath and use import statements in your java code to include the required Classes.
Recently I have encountered some problem which seems a little strange to me.
In order to use some predefined class, I imported two .jar files say foo.jar and bar.jar(Both were written by others)
And my source code is like the following:
package jerry.deque
public class Deque {
.....
.....
Foo item = new Foo(); //Already defined in the foo.jar
.....
}
I added the external library exactly as what How to Import a Jar in Eclipse
did. But when I tried to use the class defined in foo.jar Eclipse shows me that "Foo can't be resolved to a type".
I spent a lot of time to fix this problem and finally succeeded after I removed
the clause: "package jerry.deque" at the beginning of my class file.
I think this is weird because just a few days ago when I was doing some Android development, I followed the same way to add a Twitter API library. And it works fine even when I declared "package jerry.search_twittes" at the beginning of my .java
file. I'm confused by this problem and couldn't figure out what's going wrong. Could someone help me to explain it in detail? Thanks very much.
Check that Foo is same package as Deque class. If they are not same
package, you need to import Foo class in Deque class.
For example,
package jerry.deque;
import packagename.foo; // packagename.foo
public class Deque {
.....
.....
Foo item = new Foo(); //Already defined in the foo.jar
.....
}
Added Explanation
I want you to check access modifier of Foo class carefully.
There are 2 access level for top level(class) access control . These
are public, or package-private (no explicit modifier).
Your Foo class is under default package(not specified package)and may be no explicit access modifier. Hope so! Then, all classes under default package can access to Foo class. That's why when you remove package jerry.deque clause, it works.
Similarly, I want you to check Android development java code in which it works fine even when you declared "package jerry.search_twittes". In that case, classes inside Twitter API library's access modifier is public.So you can access it from anywhere.
For more information you can read this.Is this information helpful???
Foo is in default package. Classes from default package cannot be imported directly.
So when you remove the package declaration in your code, you don't get the error.
You can look for reflection api or write a proxy in the default package for that class.
I have successfully created an Acceleo module for M2T purposes and am trying to execute it from a Java program.
This is what I tried :
String[] str = {"/home/hamza/workspace/HLRedundancy/model/System1.xmi", "/home/hamza/workspace/HLRedundancy/"};
Generate.main(str);
Generate being the name of the Acceleo module I created and thus, the name of the Java class containing the Acceleo generation methods.
Here is the error I'm always getting :
Exception in thread "main" org.eclipse.acceleo.engine.AcceleoEvaluationException: The type of the first parameter of the main template named 'generateElement' is a proxy.
at org.eclipse.acceleo.engine.service.AcceleoService.doGenerate(AcceleoService.java:566)
at org.eclipse.acceleo.engine.service.AbstractAcceleoGenerator.generate(AbstractAcceleoGenerator.java:193)
at org.eclipse.acceleo.engine.service.AbstractAcceleoGenerator.doGenerate(AbstractAcceleoGenerator.java:158)
at HighLevelGenerator.main.Generate.doGenerate(Generate.java:250)
at HighLevelGenerator.main.Generate.main(Generate.java:160)
at Execute.main(Execute.java:11)
I've been searching for a while about this error but I have no idea about its cause.
Any idea about a solution to my problem ?
Thanks
The most common cause of this issue is failure in properly registering the metamodel and factory corresponding to your inpu model (System1.xmi).
If you look at the comments in the generated class "Generate.java", you will notice a number of places where we indicate steps to follow if running in standalone. The most important begin registerPackages where you are required to register your metamodel.
If you debug the launch down to the point where the model is loaded (place a breakpoint right after the line model = ModelUtils.load(newModelURI, modelResourceSet);), you can look at the model.eResource().getErrors() list to see whether there were errors loading your model.
You might also be interested in looking at this video describing the process (registration required) .
Check out the first line of your acceleo module,
what is the URI of the metamodel? Does it start with 'http://' ?
Maybe this can help:
Acceleo stand alone - first parameter is proxy
This issue happen when your meta model contains sub-packages and the top package not contain any class.
to solve the problem, add a Dummy class the the top package and regenerate the meta-model code. It worked fine for me.