Java

package zda;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.List;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.NumberFormat;

import javax.swing.BoxLayout;
import javax.swing.GroupLayout;
import javax.swing.JButton;
import javax.swing.JFormattedTextField;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSplitPane;
import javax.swing.JTextField;
import javax.swing.ListSelectionModel;
import javax.swing.SpringLayout;

public class TestInvoice extends JFrame
{

	public static void main(String[] args)
	{
		Contractor k1 = new Contractor("Some company \nsome adress, adress", "123-123-123");

		Invoice f1 = new Invoice(k1);
		Invoice f2 = new Invoice(k1);


		f1.addPosition("Kredki 3szt", Invoice.Measure.QTY, 5, 3.2, Invoice.VAT.s23);
		f1.addPosition("Flamastry 6szt", Invoice.Measure.QTY, 5, 4.59, Invoice.VAT.s23);
		f1.addPosition("Plastelina 12 kolorów", Invoice.Measure.QTY, 2, 8.22, Invoice.VAT.s23);
		f1.addPosition("Ołówki 3szt", Invoice.Measure.QTY, 1, 6.00, Invoice.VAT.s23);
		f1.addPosition("Ołówkek HB", Invoice.Measure.QTY, 5, 1.2, Invoice.VAT.s08);

		System.out.println(f1);

		f2.addPosition("Kredki 3szt", Invoice.Measure.QTY, 5, 3.2, Invoice.VAT.s23);
		f2.addPosition("Flamastry 6szt", Invoice.Measure.QTY, 5, 4.59, Invoice.VAT.s23);
		f2.addPosition("Plastelina 12 kolorów", Invoice.Measure.QTY, 2, 8.22, Invoice.VAT.s23);
		f2.close();
		f2.addPosition("Ołówki 3szt", Invoice.Measure.QTY, 1, 6.00, Invoice.VAT.s23);
		f2.addPosition("Ołówkek HB", Invoice.Measure.QTY, 5, 1.2, Invoice.VAT.s08);

		System.out.println(f2);
		System.out.println(Math.round(2022.0000000000002) / 100.0);

		new TestInvoice();

		// ----------------------------------------------------------------------------------------
	}

	private InvoiceManager manager;

	public TestInvoice()
	{
		manager = new InvoiceManager(5);

		setLayout(new BoxLayout(getContentPane(), BoxLayout.Y_AXIS));

		JPanel leftPanel = new JPanel();
		leftPanel.setSize(400, 500);

		GroupLayout gl = new GroupLayout(leftPanel);
		gl.setAutoCreateGaps(true);
		gl.setAutoCreateContainerGaps(true);
		leftPanel.setLayout(gl);

		SpringLayout sl = new SpringLayout();
		JPanel rightPanel = new JPanel(sl);
		rightPanel.setSize(400, 500);

		JSplitPane sp = new JSplitPane();
		sp.setRightComponent(rightPanel);
		sp.setLeftComponent(leftPanel);
		sp.setPreferredSize(new Dimension(600, 600));

		JLabel lPositionsName = new JLabel("name");
		JLabel lPositionsMeasure = new JLabel("Measure");
		JLabel lPositionsQty = new JLabel("qty");
		JLabel lPositionsPrice = new JLabel("price");
		JLabel lPositionsTax = new JLabel("podatek");

		JTextField tfName = new JTextField("", 20);
		JFormattedTextField tfMeasure = new JFormattedTextField(NumberFormat.getNumberInstance());
		JFormattedTextField tfQty = new JFormattedTextField(NumberFormat.getNumberInstance());
		JFormattedTextField tfPrice = new JFormattedTextField(NumberFormat.getNumberInstance());
		JFormattedTextField tfTax = new JFormattedTextField(NumberFormat.getNumberInstance());

		gl.setVerticalGroup(gl.createSequentialGroup()
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(lPositionsName)
						.addComponent(tfName))
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(lPositionsMeasure)
						.addComponent(tfMeasure))
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(lPositionsQty)
						.addComponent(tfQty))
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(lPositionsPrice)
						.addComponent(tfPrice))
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.BASELINE).addComponent(lPositionsTax)
						.addComponent(tfTax)));

		gl.setHorizontalGroup(gl.createSequentialGroup()
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(lPositionsName)
						.addComponent(lPositionsMeasure).addComponent(lPositionsQty).addComponent(lPositionsPrice)
						.addComponent(lPositionsTax))
				.addGroup(gl.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(tfName)
						.addComponent(tfMeasure).addComponent(tfQty).addComponent(tfPrice).addComponent(tfTax)));

		JList<Invoice> list = new JList<Invoice>();
		list.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
		list.setLayoutOrientation(JList.VERTICAL);
		JScrollPane listScroller = new JScrollPane(list);
		listScroller.setPreferredSize(new Dimension(250, 80));
		rightPanel.add(listScroller);

		JLabel error = new JLabel("");
		error.setForeground(Color.red);

		JButton b = new JButton("save");
		b.addActionListener(new ActionListener()
		{
			@Override
			public void actionPerformed(ActionEvent arg0)
			{
				String name = tfName.getText();

				int Measure = ((Number) tfMeasure.getValue()).intValue();
				int qty = ((Number) tfQty.getValue()).intValue();
				int price = ((Number) tfPrice.getValue()).intValue();
				int tax = ((Number) tfTax.getValue()).intValue();

			}

		});

		JButton o = new JButton("read");
		o.addActionListener(new ActionListener()
		{
			@Override
			public void actionPerformed(ActionEvent arg0)
			{
				list.setListData(manager.getList());
			}
		});

		JButton u = new JButton("delete");
		u.addActionListener(new ActionListener()
		{
			@Override
			public void actionPerformed(ActionEvent arg0)
			{
				List<Invoice> listt = list.getSelectedValuesList();

				for (Invoice w : listt)
				{
					manager.removeInvoice(w);
				}
				list.setListData(manager.getList());
			}
		});

		getContentPane().add(sp);
		getContentPane().add(error);
		getContentPane().add(b);
		getContentPane().add(o);
		getContentPane().add(u);

		pack();
		setVisible(true);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

	}
}

package zda;

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.ArrayList;
import java.util.HashMap;


public class Invoice
{

	private Contractor client;
	private LocalDate dateOfIssue;

	private String nr;

	private static class Identifier
	{
		static int currentNumber = 0;
		static int currentMonth = 0;
		static int currentYear = 0;

		static String generateNr()
		{
			LocalDate ld = LocalDate.now();

			int year = ld.getYear();
			int month = ld.getMonthValue();
			if (year > currentYear)
			{
				currentYear = year;
				currentMonth = ld.getMonthValue();
				currentNumber = 0;
			} else if (month > currentMonth)
			{
				currentMonth = month;
				currentNumber = 0;
			}

			return (++currentNumber) + "/" + currentMonth + "/" + currentYear;

		}
	}

	public enum Measure
	{
		QTY, M, L, KG, M2
	}

	public enum VAT
	{
		s23(.23), s08(.08), s05(.05), s00(.0);

		public double rate;
		public String str;

		VAT(double rate)
		{
			this.rate = rate;
			this.str = String.format("%.0f%%", 100 * rate);
		}
	}

	private class Position
	{
		private int position;
		private String name;
		private Measure mmasure;
		private double quantity;
		private double unitPriceWithoutTax;
		private VAT tax;

		public Position(String name, Measure mmasure, double quantity, double price, VAT tax)
		{
			this.name = name;
			this.mmasure = mmasure;
			this.quantity = quantity;
			this.unitPriceWithoutTax = price;
			this.tax = tax;
			this.position = positions.size() + 1;
		}

		public double getValue()
		{
			return quantity * unitPriceWithoutTax;
		}

		public double getTax()
		{
			double d = quantity * unitPriceWithoutTax * tax.rate;
			d = Math.round(d * 100) / 100.;
			return d;
		}

		@Override
		public String toString()
		{
			return String.format("%5d | %30s | %10s | %10s | %10s | %10s | %10.2f", position, name, mmasure, quantity,
					unitPriceWithoutTax, tax.str, getValue() + getTax());
		}
	}

	public static String heading()
	{
		return String.format("%5s | %30s | %10s | %10s | %10s | %10s | %10s", "LP.", "name", "mmasure", "quantity",
				"Unit price.", "tax", "price with tax");
	}

	private ArrayList<Position> positions = new ArrayList<Position>();

	public void addPosition(String name, Measure m, double quantity, double price, VAT tax)
	{
		if (closed)
			return;

		Position p = new Position(name, m, quantity, price, tax);
		positions.add(p);
		double d = subtotals.get(tax);
		d += p.getTax();
		subtotals.put(tax, d);
		sumWithTax += p.getValue();
		sumPayment += p.getValue() + p.getTax();
	}

	private boolean closed = false;

	public void close()
	{
		closed = true;
	}

	private HashMap<VAT, Double> subtotals = new HashMap<>();
	private double sumWithTax = 0;
	private double sumPayment = 0;

	public Invoice(Contractor c)
	{
		nr = Identifier.generateNr();
		client = c;
		dateOfIssue = LocalDate.now();

		for (VAT v : VAT.values())
		{
			subtotals.put(v, 0.);
		}
	}

	@Override
	public String toString()
	{
		String invoice = "---------------------------------------------\n";
		invoice += (closed ? "C-" : "O-") + "invoice no." + nr + "\n";
		invoice += "from date " + dateOfIssue.format(DateTimeFormatter.ofPattern("d-M-y")) + "\n";
		invoice += "\nFor: \n" + client + "\n\n";
		invoice += heading() + "\n";
		for (Position p : positions)
		{
			invoice += p.toString() + "\n";
		}
		invoice += "\n";
		invoice += String.format("%-15s: %10.2f\n", "Sum without tax", sumWithTax);
		for (HashMap.Entry<VAT, Double> e : subtotals.entrySet())
		{
			if (e.getValue() > 0)
				invoice += String.format("%-15s: %10.2f\n", "SUM " + e.getKey().str, e.getValue());
		}
		invoice += String.format("%27s\n", "+ ----------");
		invoice += String.format("%-15s: %10.2f\n", "sum to pay", sumPayment);
		invoice += "---------------------------------------------\n";
		return invoice;
	}

}

package zda;

import java.util.ArrayList;

public class InvoiceManager
{

	private int maxNumber = 10;
	private ArrayList<Invoice> listOfInvoices = new ArrayList<Invoice>();
	
	public void addInvoice(Invoice w) throws IllegalArgumentException{
		if(listOfInvoices.size()< maxNumber)
			listOfInvoices.add(w);
		else 
			throw new IllegalArgumentException("No space for a new invoice");
	}
	public void removeInvoice(Invoice w){
		listOfInvoices.remove(w);
	}
	public Invoice[] getList(){
		return (Invoice[]) listOfInvoices.toArray(new Invoice[listOfInvoices.size()]);
	}
	
	public InvoiceManager(int max){
		maxNumber = max;
	}
	
}

package zda;

public class Contractor
{
	String data;
	String id;

	public Contractor(String data, String id)
	{
		this.data = data;
		this.id = id;
	}

	@Override
	public String toString()
	{
		return data + "\n" + "NIP: " + id;
	}

}

<pre> public boolean isPalindrome(int x) {
	        String raw=String.valueOf(x);
	        if(raw.charAt(0)=='-')
	            raw=raw.substring(1);
	        List<Character> list = new ArrayList<Character>();
	        for(char c:raw.toCharArray())
	            list.add(c);
	          List temp=list;
	         
	        	  Collections.reverse(list);
	       
	        return temp.equals(list);
	    }