java/CaesarovaŠifra/src/cz/frantovo/příklady/Caesar.java
author František Kučera <franta-hg@frantovo.cz>
Tue, 09 Sep 2014 15:23:12 +0200
changeset 22 8e757cdaccb9
parent 19 c681a3a6cbac
permissions -rw-r--r--
RAIIDemo: výpis potlačených výjimek
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package cz.frantovo.příklady;
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/**
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 * This program is free software: you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation, either version 3 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program. If not, see <http://www.gnu.org/licenses/>.
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 */
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import java.awt.GridLayout;
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import java.awt.HeadlessException;
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import java.awt.event.ActionEvent;
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import java.awt.event.ActionListener;
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import java.util.ArrayList;
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import java.util.Collections;
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import java.util.List;
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import javax.swing.JButton;
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import javax.swing.JFrame;
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import javax.swing.JLabel;
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import javax.swing.JTextField;
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/**
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 * @author Ing. František Kučera (frantovo.cz)
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 */
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public class Caesar extends JFrame {
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	private JTextField prostýText = new JTextField();
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	private JTextField šifrovanýText = new JTextField();
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	private JButton šifruj = new JButton("Šifruj");
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	private JButton dešifruj = new JButton("Dešifruj");
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	private static final char[] ABECEDA_ZNAKY = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".toCharArray();
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	private static final List<Character> ABECEDA;
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	private static final int SKOK = 3;
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	static {
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		List<Character> abeceda = new ArrayList<>();
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		for (char z : ABECEDA_ZNAKY) {
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			abeceda.add(z);
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		}
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		ABECEDA = Collections.unmodifiableList(abeceda);
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	}
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	public static void main(String[] args) {
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		Caesar c = new Caesar();
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		c.setVisible(true);
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	}
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	public Caesar() throws HeadlessException {
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		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
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		setTitle("Caesarova šifra");
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		setLocationRelativeTo(null);
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		setLayout(new GridLayout(3, 2));
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		add(new JLabel("Prostý text"));
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		add(prostýText);
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		add(new JLabel("Šifrovaný text"));
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		add(šifrovanýText);
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		add(šifruj);
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		add(dešifruj);
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		šifruj.addActionListener(new ActionListener() {
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			@Override
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			public void actionPerformed(ActionEvent e) {
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				šifrovanýText.setText(posuň(prostýText.getText(), SKOK));
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			}
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		});
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		dešifruj.addActionListener(new ActionListener() {
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			@Override
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			public void actionPerformed(ActionEvent e) {
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				prostýText.setText(posuň(šifrovanýText.getText(), -SKOK));
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			}
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		});
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		pack();
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	}
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	private static String posuň(String text, int oKolik) {
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		StringBuilder posunutý = new StringBuilder(text.length());
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		for (char z : text.toCharArray()) {
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			posunutý.append(posuň(z, oKolik));
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		}
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		return posunutý.toString();
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	}
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	private static char posuň(char znak, int oKolik) {
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		int původníPozice = ABECEDA.indexOf(znak);
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		if (původníPozice < 0) {
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			return znak;
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		} else {
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			int nováPozice = (původníPozice + oKolik) % ABECEDA_ZNAKY.length;
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			nováPozice = nováPozice < 0 ? ABECEDA_ZNAKY.length + nováPozice : nováPozice;
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			return ABECEDA.get(nováPozice);
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		}
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	}
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}