CS 245 Lecture 4 – Interfaces
Agenda
- what ?s
- virtual lab
- Spanish verb conjugation
- program this
- a text editor
TODO
- Keep at preassignment 1.
- Finish lab 1.
- Frolic.
- No 1/4 sheet.
Program This
public interface Conjugator {
public String getYo(String verb);
public String getTu(String verb);
public String getUsted(String verb);
public String getNosotros(String verb);
}
Write a class ArConjugator, IrConjugator, or ErConjugator that implements the Conjugator interface and transforms the verb according to the rules exemplified in the conjugations of following regular verbs:
| verb | yo | tu | usted | nosotros |
|---|---|---|---|---|
| hablar | hablo | hablas | habla | hablamos |
| comer | como | comes | come | comemos |
| vivir | vivo | vives | vive | vivimos |
Code
Verb.java
package lecture04;
public class Verb {
private String infinitive;
private Conjugator conjugator;
public Verb(String infinitive,
Conjugator conjugator) {
this.infinitive = infinitive;
this.conjugator = conjugator;
}
public String getInfinitive() {
return infinitive;
}
public Conjugator getConjugator() {
return conjugator;
}
}
Conjugator.java
package lecture04;
public interface Conjugator {
public String getYo(String verb);
public String getTu(String verb);
public String getUsted(String verb);
public String getNosotros(String verb);
}
ArErConjugator.java
package lecture04;
public class ArErConjugator implements Conjugator {
public String getYo(String verb) {
return verb.substring(0, verb.length() - 2) + "o";
}
public String getTu(String verb) {
return verb.substring(0, verb.length() - 1) + "s";
}
public String getUsted(String verb) {
return verb.substring(0, verb.length() - 1);
}
public String getNosotros(String verb) {
return verb.substring(0, verb.length() - 1) + "mos";
}
}
IrConjugator.java
package lecture04;
public class IrConjugator implements Conjugator {
public String getYo(String verb) {
return verb.substring(0, verb.length() - 2) + "o";
}
public String getTu(String verb) {
return verb.substring(0, verb.length() - 2) + "es";
}
public String getUsted(String verb) {
return verb.substring(0, verb.length() - 2) + "e";
}
public String getNosotros(String verb) {
return verb.substring(0, verb.length() - 1) + "mos";
}
}
Verber.java
package lecture04;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.ArrayList;
public class Verber {
private ArrayList<Verb> verbs;
public Verber() {
verbs = new ArrayList<Verb>();
}
public void add(Verb verb) {
verbs.add(verb);
}
public void showTable(String path) throws FileNotFoundException {
PrintWriter out = new PrintWriter(path);
for (Verb verb : verbs) {
Conjugator c = verb.getConjugator();
out.printf("%s,%s,%s,%s,%s%n",
verb.getInfinitive(),
c.getYo(verb.getInfinitive()),
c.getTu(verb.getInfinitive()),
c.getUsted(verb.getInfinitive()),
c.getNosotros(verb.getInfinitive()));
}
out.close();
}
}
Main.java
package lecture04;
import java.io.FileNotFoundException;
public class Main {
public static void main(String[] args) throws FileNotFoundException {
Verber verber = new Verber();
Conjugator arErConjugator = new ArErConjugator();
Conjugator irConjugator = new IrConjugator();
verber.add(new Verb("abrir", irConjugator));
verber.add(new Verb("aprender", arErConjugator));
verber.add(new Verb("bailar", arErConjugator));
verber.add(new Verb("caminar", arErConjugator));
verber.add(new Verb("cantar", arErConjugator));
verber.add(new Verb("comprender", arErConjugator));
verber.add(new Verb("escribir", irConjugator));
verber.add(new Verb("leer", arErConjugator));
verber.add(new Verb("recibir", irConjugator));
verber.showTable("/Users/johnch/Desktop/spanish.csv");
}
}
TextEater.java
package lecture04;
import java.awt.BorderLayout;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JTextArea;
public class TextEater {
public static void main(String[] args) {
final JFrame frame = new JFrame("TextEater");
JMenuBar menuBar = new JMenuBar();
frame.setJMenuBar(menuBar);
JMenu fileMenu = new JMenu("File");
menuBar.add(fileMenu);
JMenuItem openMenuItem = new JMenuItem("Open");
fileMenu.add(openMenuItem);
final JTextArea textArea = new JTextArea();
frame.add(textArea, BorderLayout.CENTER);
textArea.setFont(new Font(Font.MONOSPACED, Font.PLAIN, 18));
openMenuItem.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent arg0) {
try {
JFileChooser fileChooser = new JFileChooser();
int status = fileChooser.showOpenDialog(frame);
if (status == JFileChooser.APPROVE_OPTION) {
File selectedFile = fileChooser.getSelectedFile();
Scanner in = new Scanner(selectedFile);
while (in.hasNextLine()) {
textArea.append(in.nextLine() + "\n");
}
in.close();
}
} catch (IOException e) {
throw new RuntimeException(e);
}
}
});
frame.setSize(512, 512);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
}
}
Haiku
A bleak dawn ahead
My code does nothing but wait
Execution comes
My code does nothing but wait
Execution comes