java - ’ right single quotation char file writing and reading

Question

I have this code to search a document and save the sentences to a ArrayList<StringBuffer> and save this object in a file

public static void save(String doc_path) {
    StringBuffer text  = new StringBuffer(new Corpus().createDocument(doc_path + ".txt").getDocStr());
    ArrayList<StringBuffer> lines = new ArrayList();
    Matcher matcher = compile("(?<=\n).*").matcher(text);
    while (matcher.find()) { 
        String line_str = matcher.group();
        if (checkSentenceLine(line_str)){
            lines.add(new StringBuffer(line_str));
        }          
    }
    FilePersistence.save (lines, doc_path + ".lin");  
    FilePersistence.save (lines.toString(), doc_path + "_extracoes.txt");
}

Corpus

public Document createDocument(String file_path) {
    File file = new File(file_path);
    if (file.isFile()) {
        return new Document(file);
    } else {
        Message.displayError("file path is not OK");
        return null;
    }
}

FilePersistence

public static void save (Object object_root, String file_path){
    if (object_root == null) return;
    try{
        ObjectOutputStream output = new ObjectOutputStream(new FileOutputStream (file_path));
        output.writeObject(object_root);
        output.close();
    } catch (Exception exception){
        System.out.println("Fail to save file: " + file_path + " --- " + exception);
    }
}

public static Object load (String file_path){
    try{            
        ObjectInputStream input = new ObjectInputStream(new FileInputStream (file_path));
        Object object_root = input.readObject();
        return object_root;
    }catch (Exception exception){
        System.out.println("Fail to load file: " + file_path + " --- " + exception);
        return null;
    }
}

the problem is, the document has some right single quotation characters as apostrophes, and when I load it and print on screen I get some odd squares instead of apostrophes on netBeans and Â' if I open the file on notepad and this is preventing me to properly handle the extracted sentences or at least showing them properly. At first I thought it was due to encoding incompatibility.

Then I tried changing encoding on project properties to CP1252 but it only changes the blank squares to question marks and on notepad still the same Â'

I also tried using

String line_str = matcher.group().replace("’","'")

and

String line_str = matcher.group().replace('\u2019','\')

but it does nothing

Update:

if (checkSentenceLine(line_str)){
        System.out.println(line_str);
        lines.add(new StringBuffer(line_str));
    }

This is before saving to a binary file. It already mess up the single quotes. shows as blank squares in UTF8 and as ? in CP1252. Makes me think the problem is when reading from the .txt

weird thing is that if i do this:

System.out.println('\u2019');

shows a perfect right single quote. the problem is only when reading from a .txt file, which makes me think it's a problem with the method I'm using to read from file. It also happens to bullet point symbols.

Maybe the problem is when parsing StringBuffer to String? if so, how could I prevent this from happening?