Java™ Application Development on Linux - Dator

17.4 SWT and GCJ397$ gcj -c SomeClass.java -o SomeClass.oFiles that do contain native methods are compiled with a command linethat looks like this:$ gcj -fjni -c SomeClass.java -o SomeClass.oThat said, it does no harm to compile a source file that has no nativemethods with the -fjni flag. This gives us a quick and dirty way to make ourlibrary file.$ find . -name "*.java" -exec gcj -fjni -c {} \; -printRemember, you are in UNIX-land. Leverage your tools! In this case, theadvantage of using find is that, should the SWT source change (classes addedor removed), our “compile process” will handle it. Obviously, you can take thisin more sophisticated directions with make or ant. But this will get the jobdone for us for now.That will compile all of the SWT source. 20 Next, we want to assemble allof the object files produced into a shared object.$ gcj -shared -o swt.so $(find . -name "*.o" -print)Once again, we leverage our tools. This time, we use bash executionquotes around our find command to get all of the .o filenames added to ourgcj command that builds the shared library. For our final trick, we will compileour HelloWorld class from the start of this chapter with gcj and our new SWTshared library:20. When we did this with Eclipse 2.1 GTK and gcj version 3.2.2, we had one compile errorwhere the return type of the org.eclipse.swt.custom.TableCursor.traverse()method was void, whereas the Control.traverse() method (from whichTableCursor inherits) was boolean. So we hacked it. We changed the return type ofTableCursor.traverse() to boolean and had it return true. We didn’t test to see if thiswas right! Use at your own peril!