Absolute beginner question

Hi, I am trying to make with a Swing GUI and I planned to
"store"
all the data from the GUI files in one class like this:

class InputData {
    String inputFile="";
    String outputFile="";
    String logFile="";
    setInputFile() {}
    setOutputFile() {}
    setLogFile() {}
    log(){}
}

and more... My problem now is that I can't make the "log" system
work so form the main class I woudl say:

    id=InputData();
    id.setLogFile("test");
    id.log("Log message");

So far, I've been testing with this:

import java.io.*;

public class TestLog {
    String a;
    FileWriter fstream;
    BufferedWriter out;
    static TestLog t;

    void set() {
    a="out.txt";
    try {
        fstream = new FileWriter(a);
        out = new BufferedWriter(fstream);
    } catch (Exception e ) {
        System.out.println("Exception a");

    }
    }
    void log(String s) {
    System.out.println("Test");
    try { out.write("test"); }
        catch (Exception e ) {
        System.out.println("Exception b");
    }
    }
    public static void main(String argv[]) {
    t=new TestLog();
    t.set();
    t.log("test log");
    }
}

The out.write("test"); is executed, but the file "out.txt"
stays emty. Any hint?

Thanks in advance...
--
Lord Eldritch