I am really stuck on this one. The code just displays the contents of one file. I tried different ways of reading the contents but it doesn't make any difference. I didn't find anything helpful in the help section so far... Any hints?
public class Solution {
    public static String firstFileName;
    public static String secondFileName;
    public static BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

    static{
        try {
            firstFileName = reader.readLine();
            secondFileName = reader.readLine();
            reader.close();
        }
        catch(IOException e) {
            System.out.println("Inside Solution.static: Enter two valid lines");
        }
    }

    public static void main(String[] args) throws InterruptedException {
        systemOutPrintln(firstFileName);
        systemOutPrintln(secondFileName);
    }

    public static void systemOutPrintln(String fileName) throws InterruptedException {
        ReadFileInterface f = new ReadFileThread();
        f.setFileName(fileName);
        f.start();
        f.join();
        System.out.println(f.getFileContents());
    }

    public interface ReadFileInterface {

        void setFileName(String fullFileName);

        String getFileContents();

        void join() throws InterruptedException;

        void start();
    }

    public static class ReadFileThread extends Thread implements ReadFileInterface{
        private StringBuffer fileContents = new StringBuffer();
        private String fileName = "";
        @Override
        public void setFileName(String fullFileName) {
            this.fileName = fullFileName;
        }

        @Override
        public String getFileContents() {
            return this.fileContents.toString().trim();
        }

        @Override
        public void run() {

            try {
                FileReader fileReader = new FileReader(fileName);
                BufferedReader reader1 = new BufferedReader(fileReader);

                while ((reader1.readLine() != null)) {
                    fileContents.append(reader1.readLine() + " ");
                }
            }
                catch (IOException e) {
                    System.out.println("Inside ReadFileThread.run(): IOException");
                }

            }
        }
    }
Thanks in advance!