Exception in thread "main" java.lang.IllegalStateException: ??

//PARSE CLASS:
 
import java.io.BufferedReader;
import java.io.FileOutputStream;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.text.DateFormat;
import java.text.DecimalFormat;
import java.text.NumberFormat;
import java.text.ParseException;
import java.util.ArrayList;
import java.util.Date;
import java.util.Locale;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
 
public class Parse {
 
	ArrayList <Customer> custlist = new ArrayList <Customer>();
 
 
	public static void main(String[] args) throws java.io.IOException, NumberFormatException, ParseException {
 
		new Parse();
	}
 
	public Parse() throws ParseException, NumberFormatException, IOException
	{
		String line = null;
		BufferedReader in = new BufferedReader(new FileReader("Customers.txt"));
		Pattern namePattern = Pattern.compile("Name: (.*)");
		Pattern customerNoPattern = Pattern.compile("Customer no: (.*)");
		Pattern postCodePattern = Pattern.compile("Post code: (.*)");
		DecimalFormat nf = new DecimalFormat("ddd");
		DateFormat df = DateFormat.getDateInstance();
		line = null;
		while (null != (line = in.readLine())) {
 
			String name = null;
			Matcher nameMatcher = namePattern.matcher(line);
			if (nameMatcher.matches()){
				name = nameMatcher.group(1);
			}
 
			String customerNumber = null;
			double customerNo = 0;
			Matcher customerNoMatcher = customerNoPattern.matcher(line);
			if (customerNoMatcher.matches()){
				customerNumber = customerNoMatcher.group(1);
				customerNo = Double.parseDouble(customerNumber);
 
			}
 
 
			String postCode=null;;
			Matcher postCodeMatcher = postCodePattern.matcher(line);
			if (postCodeMatcher.matches()){
				postCode = postCodeMatcher.group(1);
			}
 
			String telephone = null;
			int telephoneNo = 0;
			Pattern telephoneNoPattern = Pattern.compile("Telephone no: (.*)");
			Matcher telephoneNoMatcher = telephoneNoPattern.matcher(line);
			if (telephoneNoMatcher.matches()){
				telephone = telephoneNoMatcher.group(1);
				telephoneNo = Integer.parseInt(telephone);
			}
 
			String lastdate = null;
			Pattern lastModifiedPattern = Pattern.compile("Last modified: (.*)");
			Matcher lastModifiedMatcher = lastModifiedPattern.matcher(line);
			lastdate = lastModifiedMatcher.group(1);
			Date lastModified = df.parse(lastdate);
 
			Customer s = new Customer(name, customerNo, postCode, telephoneNo, lastModified);
			custlist.add( s);
		}
 
	}
 
 
	void fmtDateNumber(Locale loc) throws IOException
	{
		FileWriter fw;
		fw = null;
		try {
			fw = new FileWriter("Customers" + loc.getDisplayCountry() + ".txt");
		} catch (final IOException ioe) {
			System.out.println("Error");
		}
		final NumberFormat numfmt = NumberFormat.getNumberInstance(loc);
		final DateFormat datafmt = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, loc);
		for (final Customer c: custlist) {
			fw.write("Name: " + c.getName()+"\n");
			fw.write("Customer no: " + numfmt.format(c.getCustomerNo())+"\n");
			fw.write("Post code: " + c.getPostCode()+"\n");
			fw.write("Telephone no: " + c.getTelephoneNo()+"\n");
			fw.write("Last modified: " + datafmt.format(c.getLastModified())+"\n");
		}
		try {
			fw.close();
		} catch (final IOException ioe) {
			System.out.println("Error");
		}
	}
 
	void fmtDateNumberBinary(Locale loc) throws IOException
	{
 
		FileOutputStream out = new FileOutputStream("Customers" + loc.getDisplayCountry() + ".dat");
		ObjectOutputStream s = new ObjectOutputStream(out);
 
		final NumberFormat numfmt = NumberFormat.getNumberInstance(loc);
		final DateFormat datafmt = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, loc);
		for (final Customer c: custlist) {
			s.writeObject("Name: " + c.getName()+"\n");
			s.writeObject("Customer no: " + numfmt.format(c.getCustomerNo())+"\n");
			s.writeObject("Post code: " + c.getPostCode()+"\n");
			s.writeObject("Telephone no: " + c.getTelephoneNo()+"\n");
			s.writeObject("Last modified: " + datafmt.format(c.getLastModified())+"\n");
 
			out.close();
			s.close();
		}
	}
 
 
 
 
	public void saveIndex()
	{
		ObjectOutputStream output;
 
		try
		{
			output = new ObjectOutputStream(new FileOutputStream( "Customers.index" ) );
			output.writeObject(custlist);
			output.close();
		}
		catch ( IOException ioException )
		{
			System.err.println( "Error opening file" );
		}
 
	}
 
 
 
}
 
 
 
 
 
 
 
import java.util.Date;
 
 
//CUSTOMER CLASS:
 
class Customer
{
 
 
	private String name;
	private double customerNo;
	private String postCode;
	private int telephoneNo;
	private Date lastModified;
	public Customer( String name,double customerNo, String postCode,int telephoneNo, Date lastModified)
	{
		this.name=name;
		this.customerNo=customerNo;
		this.postCode=postCode;
		this.telephoneNo=telephoneNo;
		this.lastModified=lastModified;
	}
 
 
	public String getName() {
		String name = null;
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public double getCustomerNo() {
		double customerNo = 0;
		return customerNo;
	}
	public void setCustomerNo(double customerNo) {
		this.customerNo = customerNo;
	}
	public String getPostCode() {
		String postCode = null;
		return postCode;
	}
	public void setPostCode(String postCode) {
		this.postCode = postCode;
	}
	public int getTelephoneNo() {
		int telephoneNo = 0;
		return telephoneNo;
	}
	public void setTelephoneNo(int telephoneNo) {
		this.telephoneNo = telephoneNo;
	}
	public Date getLastModified() {
		Date lastModified = null;
		return lastModified;
	}
	public void setLastModified(Date lastModified) {
		this.lastModified = lastModified;
	}
 
}

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