How to make IntelliJ show the real names for method parameters? - java

How to I setup the IDEA IDE, so that it shows real param names for methods in build-in classes?
mvn clean install dependency:sources did not help me
upd:
HttpExchange from package
import com.sun.net.httpserver.HttpExchange

The library you want to use does not have debug information included in the bytecode which is (for now) needed for this to work. Source is not enough.
If you cannot locate a debug build you may have to compile it yourself. If you cannot access the source, you may need to ask the vendor politely.

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Java not processing JUnit jar

I am unable to compile tests with JUnit. When I attempt to do so, I get this error:
package org.junit.jupiter.api does not exist
I get this error compiling the tests even if I put the .jar in the same directory and compile as follows:
javac -cp junit4-4.12.jar Tests.java
The contents of Test.java are:
import static org.junit.jupiter.api.Assertions.assertEquals;
import org.junit.jupiter.api.Test;
public class Tests {
... several tests ...
It's not clear to me what the issue is, and as far as I can tell, it should work with the .jar -- it's the one from /usr/share/java, where it was installed when I installed junit.
As #DwB has already mentioned you have wrong junit version.
Here is what is jupiter in JUnit: http://junit.org/junit5/docs/current/user-guide/#overview-what-is-junit-5
In simple words JUnit Jupiter API is a set of new classes which were written and introduced in junit 5 version only. And ur trying to use 4 version.
And also i want to clarify some points.
even if I put the .jar in the same directory and compile as follows
It does not matter actually is your file in the same directory or not. Its all about it's path. If you are setting jar only by name of jar file (as you did) then your path becomes relative to your current directory from where u execute javac command. You can just use absolute path and run this command from every directory you want.
https://docs.oracle.com/javase/8/docs/technotes/tools/windows/classpath.html (this one is for windows but for other os there are only minor changes in path writing)
If you get errors like package does not exist, classnotfound or anything similar then such kinds of errors almost always mean you have something wrong with your classpath or dependencies. In your case you simply had wrong version.
Now about finding necessary deps. In java world one of the main places for dependencies is maven central. Almost every opensource library can be found there and maven by default uses this repository to find and load dependencies (in your case these are jars) from there. Also you can use it to get necessary jars manually by simply using it's UI (https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter-api/5.0.0). There is download jar button.
Now if you know package or class but do not know in what dependency (jar for simplicity) it is located. In this case you can use http://grepcode.com or other resources which allow to search within available source code withit different repositories. In most cases this work. With juniper i did not manage to find smth there but in other cases this may help) Or the most simple case is just google package and in most cases it also will help to define entry point.
Now about solving ur issue. It seems that you will need as api as implentation. You will definitely need this one https://mvnrepository.com/artifact/org.junit.jupiter/junit-jupiter-api/5.0.0 but it seems that you will need juniper-engine too. First try adding only API and then just go on adding necessary libraries according to errors. You can add multiple jars to cp (read provided class path guide from oracle).

Compiling with Ant

I have two .class files that I'm supposed to black box test. These are in a package one.two.three. My tests are also in the same package. There is a third .class file in the same package whose purpose is to hold an enum variable for the Orders class I'm supposed to test. In eclipse, I'm able to get the junit tests for Orders to work by importing the enum directly e.g.
import one.two.three.Orders.ShippingMethod;
If I try to do this using Ant or via the command line, I get the error "package one.two.three.Orders does not exist". If I change the import statement to
import one.two.three.*;
Ant, Eclipse, and the terminal cannot find any of the classes I have. I need to compile and run the test cases with Ant. The classes are in bin/one/two/three Any help would be greatly appreciated, thanks.
Import Orders, as it is the class, and assuming that ShippingMethod is an enum within that class, the correct way to reference its type is Orders.ShippingMethod.
Attempting to import a class's internal types sometimes works oddly in Eclipse. This is likely due to Eclipse not using the javac compiler packaged in your jdk, while Ant does (it has to, because Ant doesn't ship an embedded compiler).
import one.two.three.Orders;
public class Whatever {
private Orders.ShippingMethod shipMethod;
}
This should work in everything, as it's the right way to do it.
import one.two.three.Orders.ShippingMethod;
could easily confuse most compilers as there is not a
one/two/three/Orders/ShippingMethod.class
file, which means the class loader won't find it at runtime.
I'll bet it's a bug in the Eclipse embedded compiler, as I've seen quite a few. On the bright side, the Eclipse embedded compiler exists to provide faster, tighter integration between code editing and Eclipse. On the dark side, that means that sometimes the Eclipse compiler and the javac compiler differ. When in doubt, the javac compiler is probably correct.
You'll need to set the classpath.
I don't know exactly on Eclipse (I use NetBeans), but I click on Libraries -> add JAR/Folder.
For command line, you need to specify class path
java -cp path/to/my/files (...)

Is there any maven plugin allowing to generate a file listing implementations of an interface?

I would like, before packaging phase, to obtain a list of classes implementing a given interface (for this file to be added in output jar). How can I do that ?
The javadoc method would probably work. Another option would be to write an ant script to do it. You can use the maven any plugin to help accomplish this:
http://maven.apache.org/plugins/maven-antrun-plugin/
Well, since I've already implemented that a few times, I now have a ready to use method.
Add the GMaven Plus plugin to your build
Declare an execution using project classpath
in this execution, add the reflections Java library
In your groovy script, find the interface ou want implementations of
Report classes implementing that interface the way you want.

GWT Maven Plugin -- gwt:run works but gwt:compile doesn't. Why?

I'm using gwt-maven-plugin to manage a GWT project. I use the gwt:run goal all the time to run locally in "dev mode" for testing. I now want to compile my project into a war for deployment on Tomcat. When I run gwt:compile, however, I get compile errors that indicate a classpath configuration issue. An example:
Finding entry point classes
[ERROR] Errors in 'shared.MyClass.java'
[ERROR] Line 4: The import server.model.MyObject cannot be resolved
Any ideas? Do I need to manually add the server package to some config file somewhere? Thanks in advance for any info.
-tjw
Ok, I found the problem. I found this in the GWT forums by Thomas Broyer (a GWT dev):
I mean you have to "javac" classes that are referenced from
annotations (in this case, the PlaceTokenizer classes referenced from
#WithTokenizers; that'd be true also of your service, domain object,
locator or service locator with RequestFactory, unless you use
#ServiceName and #ProxyForName). Otherwise, GWT can work with only
the *.java files, without the *.class.
I am trying to load in these classes from annotations since they are used with RequestFactory. My question is now this: How is this restriction not completely insane?

How can I generate list of classes in order of dependency?

I'm doing a build script for a Java application to run inside the Oracle JVM. In order to import the 50-odd classes, it appears I need to bring them in in order, so any dependencies are present before compilation.
For each class, I'm running 'create or replace and compile java source {className} as {classPath}' for each file. Doing this gives me a compilation error, as the required class(es) are not imported.
How can I generate a list of the classes, in dependency order - that is, as you go down the list, the class's dependencies are listed above. I would prefer to do this as an Ant task.
Also if you have a better idea of how to get these classes imported, I'd love to hear your ideas.
I can't imagine why you'd need to do this, but if you really need to do this, I wonder if hacking a little classloader that prints out each class as it loads and load your app from there would give you a dependency graph?
Compile the classes in the filesystem using the Ant task javac. Use the task depend if more rigorous dependency checking is needed. Use the loadjava tool to load the .class and .java files into the database in arbitrary order.
In order to import the 50-odd classes, it appears I need to bring them in in order so any dependencies are present before compilation.
I have never had to do such a thing simply to compile Java.
This is what Ant was born for. I'd recommend just doing this with Ant. Set the <classpath> and you'll have no trouble.
Brute force method: put the 50 CREATEs in a batch file and execute it until no errors are found. Create the loop in a shell script. Of course it will never end if there are errors in the sources, but I'm assuming they are ok.
Can you not load in a jar file? Why does it have to be individual classes?

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