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gongpex

proble with arrayList

3 posts in this topic

Hello everyone,

 

long time no see,

 

 

I think this will more easily if you ever read Head First Java book,

 

When I tried code on that book on page 450 (chapter 14) about QuizCard builder.

 

this the code :

import  java.util.*;import  java.awt.event.*;import  javax.swing.*;import  java.awt.*;import  java.io.*;  public class QuizCardBuilder {     private JTextArea question;     private JTextArea answer;     private ArrayList<QuizCard> cardList;     private JFrame frame;     public static void main(String[] args)  {        QuizCardBuilder builder = new QuizCardBuilder();        builder.go();     }    public void go() {      //build GUI         frame = new JFrame("Quiz Card Builder");      JPanel mainPanel = new JPanel();      Font bigFont = new Font("sanserif", Font.BOLD, 24);      question = new JTextArea(6,20);      question.setLineWrap(true);      question.setWrapStyleWord(true);      question.setFont(bigFont);      JScrollPane qScroller = new JScrollPane(question);      qScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);      qScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);            answer = new JTextArea(6,20);      answer.setLineWrap(true);      answer.setWrapStyleWord(true);      answer.setFont(bigFont);        JScrollPane aScroller = new JScrollPane(answer);      aScroller.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);      aScroller.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);      JButton nextButton = new JButton("Next Card");         cardList = new ArrayList<QuizCard>();      JLabel qLabel = new JLabel("Question :");      JLabel aLabel = new JLabel("Answer : ");      mainPanel.add(qLabel);      mainPanel.add(qScroller);      mainPanel.add(aLabel);      mainPanel.add(aScroller);      mainPanel.add(nextButton);        nextButton.addActionListener(new NextCardListener());      JMenuBar menuBar = new JMenuBar();      JMenu fileMenu = new JMenu("File");      JMenuItem newMenuItem = new JMenuItem("New");      JMenuItem saveMenuItem = new JMenuItem("Save");      newMenuItem.addActionListener(new NewMenuListener());            saveMenuItem.addActionListener(new SaveMenuListener());      fileMenu.add(newMenuItem);      fileMenu.add(saveMenuItem);      menuBar.add(fileMenu);      frame.setJMenuBar(menuBar);      frame.getContentPane().add(BorderLayout.CENTER, mainPanel);      frame.setSize(500,600);      frame.setVisible(true);    }       public class NextCardListener implements ActionListener {      public void actionPerformed(ActionEvent ev) {        QuizCard card = new QuizCard(question.getText(), answer.getText());        cardList.add(card);        clearCard();     }   }    public class SaveMenuListener implements ActionListener {       public void actionPerformed(ActionEvent ev) {        QuizCard card = new QuizCard(question.getText(), answer.getText());        cardList.add(card);                 JFleChooser fileSave = new JFileChooser();        fileSave.showSaveDialog(frame);        saveFile(fileSave.getSelectedFile());     }   }   public class NewMenuListener implements ActionListener {       public void actionPerformed(ActionEvent ev) {        cardList.clear();        clearCard();      }   }  private void clearCard() {     question.setText("");     answer.setText("");     question.requestFocus();  }  private void saveFile(File file) {    try {         BufferedWriter writer = new BufferedWriter(new FileWriter(file));        for(QuizCard card:cardList) {            writer.write(card.getQuestion() + "/");            writer.write(card.getAnswer() + "n");        }     writer.close();     } catch(IOException ex) {       System.out.println("couldn't write the cardList out");       ex.printStackTrace();   }  }}

the issue is start from : private ArrayList<QuizCard> cardList; .

 

when I see it using eclipse, it shown : "QuizCard cannot be resolved to a type" and can't compile.

 

Q : what's mistake on this code?

 

please someone help me

 

thanks

 

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I believe you need to import the QuizCard class.

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Pretty straight forward.

 

You are missing the class QuizCard:

 

You are creating an instance in here:

 

QuizCard card = new QuizCard(question.getText(), answer.getText());

 

Of course you need to have that class in the project.

public class QuizCard{	String question,answer;	public QuizCard(){}	public QuizCard(String q,String a){		question=q;		answer=a;	}	public String getQuestion(){return question;}	public String getAnswer(){return answer;} }

Result:

 

dzeZgAd.png

Edited by panodil

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