Grails: Integrating a Java Class
Question
I created a new Grails 3 application in IntelliJ IDE.
Here is the folder structure view from IntelliJ
I then created two files, a controller with the following code,
package grailsjavatest
import test.JavaTest;
class JavaTestController {
def index() {
JavaTest jt = new JavaTest();
render jt.someAction();
}
}
and a Java files with the following code (in src/java/test/JavaTest.java),
package test;
class JavaTest{
public String someAction()
{
return "<html> <body> <b> Hello From Java! </b> </body> </html>";
}
}
However the following project errors with the following error,
[the java process command was removed as it is a bit long.]
| Running application...
startup failed:
/Users/user/IdeaProjects/GrailsJavaTest/grails-app/controllers/grailsjavatest/JavaTestController.groovy: 2: unable to resolve class test.JavaTest
@ line 2, column 1.
import test.JavaTest;
^
1 error
FAILURE: Build failed with an exception.
* What went wrong:
Execution failed for task ':compileGroovy'.
> Compilation failed; see the compiler error output for details.
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
| Error Failed to start server (Use --stacktrace to see the full trace)
Process finished with exit code 1
If I change the controller code to,
package grailsjavatest
class JavaTestController {
def index() {
render "<html> <body> <b> Hello From Java! </b> </body> </html>";
}
}
the page renders as expect (but obviously not calling the java code).
Edit
Here is the file structure with the package created,
2 answers
solution1
1 2016-12-09 19:14:59
Your JavaTest class is declared with default (package-private) modifier, so it is only visible to other classes declared in the same 'test' package. Add the 'public' keyword to the start of the class definition (ie 'public class JavaTest{ yada, yada').
Alternatively follow the instructions given by Grails and "Run with --stacktrace option to get the stack trace." which should show you what's wrong.
solution2
0 2016-12-09 14:56:40
My previous answer made little sense.
The problem is that 'test' is not a package folder (which contain a dot in IntelliJ), but a plain folder. But in order to add a package folder to your Java folder, your Java folder needs to be marked as a 'source folder' (which have a blue color). Right-click on the java folder, select 'Mark directory as' - 'Sources root'. The 'test' folder will now automatically be marked as a package folder (at least in IntelliJ 2016.1).
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