Biojava: Package import errors

Question

The following code:

import org.biojava.bio.structure.ResidueNumber;
import org.biojava.bio.structure.Structure;
import org.biojava.bio.structure.io.PDBFileReader;
import org.biojava3.protmod.structure.ProteinModificationIdentifier;

public class Test3 { 
public static void main(String[] args) {
    try {
        PDBFileReader reader = new PDBFileReader();
        reader.setAutoFetch(true);

        // identify all modifications from PDB:1CAD and print them
        String pdbId = "1CAD";
        Structure struc = reader.getStructureById(pdbId);
        Set<ModifiedCompound> mcs = identifyAllModfications(struc);
        for (ModifiedCompound mc : mcs) {
            System.out.println(mc.toString());
        }

        // identify all phosphosites from PDB:3MVJ and print them
        pdbId = "3MVJ";
        struc = reader.getStructureById(pdbId);
        List<ResidueNumber> psites = identifyPhosphosites(struc);
        for (ResidueNumber psite : psites) {
            System.out.println(psite.toString());
        }
    } catch(Exception e) {
        e.printStackTrace();
    }
 }
}

...results in the following stream of error messages:

C:\Users\CaitlinG>javac Test3.java
Test3.java:1: error: package org.biojava.bio.structure does not exist
import org.biojava.bio.structure.ResidueNumber;
                                ^
Test3.java:2: error: package org.biojava.bio.structure does not exist
import org.biojava.bio.structure.Structure;
                                ^
Test3.java:3: error: package org.biojava.bio.structure.io does not exist
import org.biojava.bio.structure.io.PDBFileReader;
                                   ^
Test3.java:4: error: package org.biojava4.protmod.structure does not exist
import org.biojava4.protmod.structure.ProteinModificationIdentifier;
                                     ^
Test3.java:9: error: cannot find symbol
                PDBFileReader reader = new PDBFileReader();
                ^
  symbol:   class PDBFileReader
  location: class Test3
Test3.java:9: error: cannot find symbol
                PDBFileReader reader = new PDBFileReader();
                                           ^
  symbol:   class PDBFileReader
  location: class Test3
Test3.java:14: error: cannot find symbol
                Structure struc = reader.getStructureById(pdbId);
                ^
  symbol:   class Structure
  location: class Test3
Test3.java:15: error: cannot find symbol
                Set<ModifiedCompound> mcs = identifyAllModfications(struc)
                ^
  symbol:   class Set
  location: class Test3
Test3.java:15: error: cannot find symbol
                Set<ModifiedCompound> mcs = identifyAllModfications(struc)
                    ^
  symbol:   class ModifiedCompound
  location: class Test3
Test3.java:16: error: cannot find symbol
                for (ModifiedCompound mc : mcs) {
                     ^
  symbol:   class ModifiedCompound
  location: class Test3
Test3.java:23: error: cannot find symbol
                List<ResidueNumber> psites = identifyPhosphosites(struc);
                ^
  symbol:   class List
  location: class Test3
Test3.java:23: error: cannot find symbol
                List<ResidueNumber> psites = identifyPhosphosites(struc);
                     ^
  symbol:   class ResidueNumber
  location: class Test3
Test3.java:24: error: cannot find symbol
                for (ResidueNumber psite : psites) {
                     ^
  symbol:   class ResidueNumber
  location: class Test3
13 errors

I have manually downloaded every jar file for Biojava 4.2.4 and stored each of them in a desktop folder (included in my classpath), listed each individually on my classpath, and stored both in C:\program files\java\jdk1.8.0_112\jre\lib\ext and C:\program files\java\jdk1.8.0_112\jre\ext yet the errors are not resolved.

I'm using a Windows 10 machine, Java JDK8_112, and BioJava 4.2.4

Any help would be appreciated.

Thank you.