How to write only unique values into CSV file?

Question

I'm developing a CLOC program, that traverse into other program's source code and takes the values from them!, where its saving some values into CSV file using:

out.write 

the problem is that as much as I run the program as much as the values will be written in the file, despite if they are already there or not!

my question is how to tell the program to write ONLY the values that are NOT already available!

here is my code:

 private void writeReport() {
    BufferedWriter out = null;
    try {
        File file = new File("out.csv");
        boolean exists = file.exists();
        FileWriter fstream = new FileWriter(file, exists /*=append*/);
        out = new BufferedWriter(fstream);
        if (!exists) {
            out.write("Project Name;");
            out.write("Version;");
            out.write("Download Date;");
            out.write("Total Lines of Code;");
            out.write("Executable Lines;");
            out.write("Lines of Comments;");
            out.write("Trivial Lines;");
            out.write("Empty Lines;");
            out.write("Code Complexity;");
            out.write("Number of Files;"); //to be changed to numver of files 
            out.write("Average File Complexity;"); //to be changed to averag file complexity
            out.write("Total Comment Percentage;"); //total

            out.write("Total Lines of Test Code;");
            out.write("Excutable Test Lines;");
            out.write("Lines of Comments in Tests;");
            out.write("Trivial Lines in Tests;");
            out.write("Empty Lines in Tests;");
            out.write("Number of Test Files;");
            out.write("Comment Presentage in Test;");

            out.write(System.getProperty("line.separator"));

        }

        //  for (int i = 0; i < newFiles.getNrOfFiles(); i++) {
       // out.write("test" + ";");
        // out.write(newFiles.getParser(i).getSourceFile().getName()+ ";");
        out.write(String.valueOf(newFiles.getProjectName()) + ";");
        out.write(String.valueOf(newFiles.getVersionNumber()) + ";");
        out.write(String.valueOf(newFiles.getDownloadDate()) + ";");
        out.write(String.valueOf(newFiles.sumLinesOfCode()) + ";");
        out.write(String.valueOf(newFiles.sumLinesOfStatements()) + ";");
        out.write(String.valueOf(newFiles.sumLinesOfComments()) + ";");
        out.write(String.valueOf(newFiles.sumTrivialLines()) + ";");
        out.write(String.valueOf(newFiles.sumEmptyLines()) + ";");
        out.write(String.valueOf(newFiles.sumComplexity()) + ";");
        out.write(String.valueOf(newFiles.getNrOfFiles()) + ";");
        out.write(String.valueOf(newFiles.sumAvgComplexity()) + ";");
        out.write(String.valueOf((100 * newFiles.sumLinesOfComments()) / newFiles.sumLinesOfCode() + "%") + ";");
        out.write(String.valueOf(testFiles.sumLinesOfCode()) + ";");
        out.write(String.valueOf(testFiles.sumLinesOfStatements()) + ";");
        out.write(String.valueOf(testFiles.sumLinesOfComments()) + ";");
        out.write(String.valueOf(testFiles.sumTrivialLines()) + ";");
        out.write(String.valueOf(testFiles.sumEmptyLines()) + ";");
        out.write(String.valueOf(testFiles.getNrOfFiles()) + ";");
        out.write(String.valueOf((100 * testFiles.sumLinesOfComments()) / testFiles.sumLinesOfCode() + "%") + ";");

        out.write(System.getProperty("line.separator"));

      //  }

        //Close the output stream
        out.close();
    } catch (Exception e) {
        System.err.println("Error: " + e.getMessage());
        //  return;
    }
}

So, how can I do that?

Best regards