Is there a problem with BufferedWriter in JAVA?

I'm quite new in OOP and Java programming, so please, forgive me. I wrote a small class in which I try to write a String in a file using the BufferedReader class. Everything works just fine, but the file is "empty", I mean that I can't see anything inside.

But for sure, data are stored, because when I close Eclipse and re open it again and run the driver class to make my tests, data are restored from the file. By the way I use a "try with resources" mechanism so my file is "closed" automatically.

Does someone already meet this problem? My Eclipse version is "2018-12"

Below, you have the small class with a "writeToFile" method in which I use the BufferedReader class.

package parlons.code.tipcalulator.utilities;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;

public class FileManagement {
    private File tipFile;
    
    public FileManagement(String tipsFileName) {
        this.tipFile = new File("/"+tipsFileName);
        
    }
    public String readFromFile() {
        String tip = null;
        try(BufferedReader bufferedReader = new BufferedReader(new FileReader(this.tipFile))) {
            tip = bufferedReader.readLine();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return tip;
        
    }
    
    public void writeToFile(String decimal) {
        try(BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(tipFile,true))){
            bufferedWriter.write(decimal);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Below, you'll find the Driver class for testing purposes.

package parlons.code.tipcalulator.utilities;

public class UtilitiesTestDriver {

    public static void main(String[] args) {

        String decimal = "108";
        FileManagement fileManagement = new FileManagement("tipFile.txt");
        fileManagement.writeToFile(decimal);
        System.out.println(fileManagement.readFromFile());
        
    }
}

As per Makoto's comment above, everything works fine if you change to e.g.:

        this.tipFile = new File("./"+tipsFileName);

This would create the tipFile.txt file (containing 108) in the root directory of your project (as opposed to the root of the filesystem - where you would probably not have write permission.)