I have developed eclipse plugin which for any given java project create GUI in form of package structure. I have successfully run my plugin for different java project.
Now, I thought should try my code in some open source project, therefore, I download JDOM Framework.
However, I found that the JDOM source code has this structure.
JDOM -> contrib -> src -> java -> org -> jdom2......
where as i assume that the project will have always below structure
Project Name -> Src -> PACKAGE NAME STARTS HERE.....
I load the classes using below code,
IPackageFragment[] packages = javaProject.getPackageFragments();
for (IPackageFragment mypackage : packages) {
if (mypackage.getKind() == IPackageFragmentRoot.K_SOURCE) {
for (ICompilationUnit unit : mypackage.getCompilationUnits()) {
// unit.getPath().toString() give me path, but how to extract only class name with package
// save it in to MAP with Package as key
}
}
}
Now, I want to show classes with only package name, therefore, I remove first two string (PROJECT NAME, SRC), but this cannot be always the case as for JDOM Framework.
Therefore, how can I get only package name along with class name using my method above? Or should I use different mechanism?
Looking at the directory structure alone seems to be an awfully error-prone way to go about it. Who knows how deep the directory tree goes? If instead you scan for Java source files, you should be able to construct a reader that finds the package declaration at the beginning of the file. If there isn't one, you don't need to worry about it. Do I need to say you can store package names in a HashSet to avoid duplicate package declarations?
The ICompilationUnit has a findPrimaryType method:
IType primaryType = unit.findPrimaryType();
and IType has getFullyQualifiedName():
String name = primaryType.getFullyQualifiedName();
Related
Can anyone tell me how to import java classes with the same names and same namespace (package names) into one maven project. I already include those clases in maven project using dependecy tags in pom file. When I want to create new instance of this class i can not define from which project to take class definition. Example:
In project abc i have clas definition:
myclass.FirstClass(){
Pivate String a;
// getter and setter for a
}
In project def i have clas definition:
myclass.FirstClass(){
Pivate String a;
// getter and setter for a
}
Now I want to use both of those definitions in third project where I should assign value for a atribut from class defined in abd to class defined in def project. I know it sound crazy, but I use it to map object for designig web services.
Thanks,
Miha
This cannot be done. Java cannot distinguish two classes with the same qualified name.
You need to rename one of the packages. If at least one of the projects abc and def is yours, this can be easily done. If not, You probably need something like the Maven shade plugin.
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 tried to search for the solution, but what I found I don't know how to apply in this situation. Please help me correct my code.
package Exercise;
public class Ex11_11 {
public static void main(String[] args) {
A a = new A(3);
}
}
class A extends B { // type A is already defined, A has a red underline
public A (int t) {
System.out.println("A's constructor is invoked");
}
}
class B { // type B is already defined, B has a red underline
public B () {
System.out.println("B's constructor is invoked");
}
}
Eclipse sometimes gets confused. If you choose Clean from the Project menu, it might fix these errors.
Well, the first thing to check is obviously whether or not you have another class called A in your file or in the same package.
I had the same problem. My computer was restarted remotely by I.T, and Eclipse did not shut down gracefully. I noticed there was an extra java file in my project that I didn't add. Deleted it, and now the error is gone.
In Project-> Clean, select "Clean projects selected below", select my project(s) and check "Start a build immediately" with "Build only selected projects".
Then problem will resolve.
Check if all your class files are saved. I've had this problem a few times: i define a class in a class file then move it in it's own one. Java gets confised, because it reads from the old version of the original file. Once you save it with the missing class definition in it and define the class in the new file all should be ok.
In your project you might have test directory with the same package structure and the same class name (for example copied without changing class name to *Test).
If none of the above solutions worked for you then it possible that Build Path is messed up. When you add a src to the build path make sure the src is not in the exclusion list. Place *(wild card) in the inclusion list and nothing in the exclusion list.
Make sure
Project | Build Automatically
is checked.
The main reason for this is that somewhere in same package you have already defined a class with name A.
which causes type A is already defined error.
check if there is any subclass or inner class named A
Have you added another project to the build path?
I had the same issue on my development environment (Eclipse).
My Maven application consumed other applications. On Eclipse, those projects were just added to the build path. One of them had the same package structure and class filename. Eclipse ends up thinking both the files which are physically different are in the same directory since the package structure and filename are same.
For example, let's say there are two files as below:
/Users/uname/home/proj1/com/app/proj/main/java/util/file1.java
and
/Users/uname/home/proj2/com/app/proj/main/java/util/file1.java
and lets say both have the package name
com.app.define.proj.util
If you add one of the project to the other, Eclipse would consider both the files to be in the same location.
I resolved by creating a JAR file out of the consumed application, adding it to the build path and removing the Eclipse project from build path.
rename the class name A to Aa or something and try to run.
Learning java newly. Can anybody clear my doubt in following?
My demo application has code like this
SourcePackages ---> ex1.pkg1
|
--->food
My ex1.pkg1 has one class called Ex11 and it contains the main function.
My food package contains one abstract class fruit and another subclass of class fruit as Apple.
I am creating an instance of Apple class in my main function in class Ex11.
The code compiles fine and runs also fine. But I am trying to understand the directory structure in java.
When I run the program I can see the following folders inside the build/class directory
ex1 -> pkg1 -> Ex11.class
food -> Apple.class and fruit.class
fruit -> empty
I don't understood why the directory fruit is created although I don't have any package named fruit? Even if I delete it and compile again its not created. But created when I run the application.
Extra Info - I am using netbean IDE
To answer your question Not exactly. You can create same directory structures ( hence same package) in different locations and even in different jars. For example; you can have directories CoreDomain\com\example and CoreServices\com\example. Now, classes within these two directories will have same package com.example even though they are in different directories ( but same directory with ref. to starting point ; as both are in com.example )
Problem
I'm writing a standalone utility program which, given a jar containing a JPA-2 annotated persistence unit, needs to programmatically get a list of all my #Entity classes in a particular persistence unit.
I'd like to decide which of 2 approaches would be the way to go to get this information, and why; or if there is another better way I haven't thought of.
Solution 1
Java program puts jar on the classpath, creates persistence unit from the classes in the jar using JavaSE methodologies. Then it uses the javax.persistence classes to get the JPA Metamodel, pull back list of class tokens from that.
EntityManagerFactory emf = Persistence.createEntityManagerFactory("MY_ PERSISTENCE_UNIT");
Metamodel mm = emf.getMetamodel();
// loop these, using getJavaType() from Type sub-interface to get
// Class tokens for managed classes.
mm.getManagedTypes();
Solution 2
Program scan the directories and files inside the specified jar for persistence.xml files, then finds one with the specified persistence unit name. Then XPath the file to get the list of <class> XML elements and read the fully qualified class names from there. From names, build class tokens.
Constraints/Concerns
I'd like to go with approach 1 if possible.
This utility will NOT run inside a container, but the jar is an EJB project designed to run inside one. How will this be a problem?
The utility will have Open-EJB available on the classpath to get implementations of all the Java EE 6 classes.
Even though the EJB project is built to run on Hibernate, the utility should not be Hibernate-specific.
Are there any stumbling blocks?
In case anyone's interested, Solution 1 worked. Here's essentially what I had to do:
public MySQLSchemaGenerator() throws ClassNotFoundException {
Properties mySQLDialectProps = new Properties();
mySQLDialectProps.setProperty("javax.persistence.transactionType", "RESOURCE_LOCAL");
mySQLDialectProps.setProperty("javax.persistence.jtaDataSource", "");
final EntityManagerFactory emf = Persistence.createEntityManagerFactory("<persistence_unit_name>", mySQLDialectProps);
final Metamodel mm = emf.getMetamodel();
for (final ManagedType<?> managedType : mm.getManagedTypes()) {
managedType.getJavaType(); // this returns the java class of the #Entity object
}
}
The key was to override my transaction type and blank out the jtaDataSource which had been defined in my persistence.xml. Turns out everything else was unnecessary.
If Your jar is well-formed (persistence.xml at the right place - in the META-INF folder), then all looks fine.
It is not necessary to run your utility inside a container, JPA is not a part of JavaEE specs.