exceptions-readandwrite/src/main/java/rocks/zipcode/AlphaCharDocument.java

package rocks.zipcode;

import java.io.*;
import java.util.Scanner;

/**
 * @author leon on 16/11/2018.
 */
public class AlphaCharDocument extends Document {

//private String fileName;
private File file;
//private FileWriter fw = new FileWriter(file);

    public AlphaCharDocument(String fileName) throws IOException {
        super(fileName);
       this.file = new File(fileName);
       // this.fileName = fileName;
       // fw = new FileWriter(file);
    }

    @Override
    public void write(String contentToBeWritten) {
        try {
            FileWriter fw = new FileWriter(file);
            isAlpha(contentToBeWritten);
            fw.write(contentToBeWritten);
            fw.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }
    }

    public String read() throws FileNotFoundException {
        try {
            Scanner scanner = new Scanner(file);
            StringBuilder sb = new StringBuilder();
            while(scanner.hasNextLine()){
                sb.append(scanner.nextLine());
            }
            String content = sb.toString();
            return content;

    } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }

    private void isAlpha(String s) throws IOException {
        if(!s.matches("[a-zA-Z\\s]*"))
            throw new IllegalArgumentException();
    }
}