javac: file not found: testdll.java
Usage: javac <options> <source files>
use -help for a list of possible options

C:UsersuserDocumentselipseworkspacetestdllsrc>javac testdll.java

C:UsersuserDocumentselipseworkspacetestdllsrctestdll.java`

C:UsersuserDocumentselipseworkspacetestdllbintestdll.class`

java version "1.8.0_40"
Java(TM) SE Runtime Environment (build 1.8.0_40-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.40-b25, mixed mode)

javac 1.8.0_40

C:Program FilesJavajdk1.8.0_40bin;
C:Program FilesJavajdk1.8.0_40jrebin;