从JTextField输入文本时触发的ActionListener

Question

I would like to ask the user a question through a JTextArea, and have the answer evaluated inside of an ActionListener. Here is my (example) code:

textField.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            final String text = textField.getText();
            textArea.setText("Is your favorite color Red?");
            if (text.replaceAll("'", "").toLowerCase().contains("yes")){
                textArea.setText("Cool!");
            }else if (text.replaceAll("'", "").toLowerCase().equals("no")){
                textArea.setText(":(");
            }
        }
    });

The problem is that because there are other questions, whenever the user types "yes", the response is "Cool!". I want it to only say "Cool!" when the answer is "yes" and the question is "Is your favorite color Red?".

Answer 1

You're operating in an event driven environment, so you need to ask the question and wait for a response from the user.

Think about it a little differently. You have a "question", which has prescribed output in response to user input.

What you need is some way to associate the response from the question with the question, lucky for us, Java is a OO language...

Start with some concept of question

public interface Question {
    public String getPrompt();
    public String getResponse(String input);
}

public abstract class AbstractQuestion implements Question {

    private String prompt;

    public AbstractQuestion(String prompt) {
        this.prompt = prompt;
    }

    @Override
    public String getPrompt() {
        return prompt;
    }

}

Now, we need some way to apply the current question...

private JTextArea ta;
//...
private Question question;
//...
public void setQuestion(Question q) {
    if (question != q) {
        question = q;
        if (question != null) {
            ta.append(question.getPrompt() + "\n");
            ta.setCaretPosition(ta.getDocument().getLength());
        }
    }
}

Now, when the ActionListener , we need to ask the Question for the response to the input...

@Override
public void actionPerformed(ActionEvent e) {
    if (question != null) {
        String response = question.getResponse(tf.getText().trim());
        ta.append(response + "\n");
        ta.setCaretPosition(ta.getDocument().getLength());
    }
}

This way, you can control the response based on the current Question

For example...

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private JTextArea ta;
        private JTextField tf;

        private Question question;

        public TestPane() {
            setLayout(new BorderLayout());
            ta = new JTextArea(10, 30);
            ta.setEditable(false);
            add(new JScrollPane(ta));

            tf = new JTextField(10);
            add(tf, BorderLayout.SOUTH);

            tf.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    if (question != null) {
                        String response = question.getResponse(tf.getText().trim());
                        ta.append(response + "\n");
                        ta.setCaretPosition(ta.getDocument().getLength());
                    }
                }
            });

            setQuestion(new AbstractQuestion("Is your favorite color Red?") {
                @Override
                public String getResponse(String input) {
                    String response = "To bad, mine is";
                    if ("yes".equalsIgnoreCase(input)) {
                        response = "Cool!";
                    }
                    return response;
                }
            });
        }

        public void setQuestion(Question q) {
            if (question != q) {
                question = q;
                if (question != null) {
                    ta.append(question.getPrompt() + "\n");
                    ta.setCaretPosition(ta.getDocument().getLength());
                }
            }
        }

    }

    public interface Question {

        public String getPrompt();

        public String getResponse(String input);
    }

    public abstract class AbstractQuestion implements Question {

        private String prompt;

        public AbstractQuestion(String prompt) {
            this.prompt = prompt;
        }

        @Override
        public String getPrompt() {
            return prompt;
        }

    }

}

This kind of approach decouples the UI/user input from the logic of the question and allows you to isolate the responsibility for generating the response to the instance of the question, allowing you to make a potentially unlimited number of questions with out the need to generate a very long list of if-else statements

Answer 2

Try something like

String question = "Is your favorite color Red?";
textArea.setText(question);
if(textArea.getText().equals(question))
{
        if (text.replaceAll("'", "").toLowerCase().contains("yes")){
            textArea.setText("Cool!");
        }else if (text.replaceAll("'", "").toLowerCase().equals("no")){
            textArea.setText(":(");
        }
}

Answer 3

You are setting the text area to "Is your favorite color Red?", but then later replacing that with "Cool!". Instead, you should use something like the following so that you only set the text of the JTextArea once with everything you need.

textField.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
         final String text = textField.getText();

         StringBuilder sb = new StringBuilder();
         sb.append("Is your favorite color Red?\n");
         if (text.replaceAll("'", "").toLowerCase().contains("yes")){
             sb.append("yes\nCool!");
         } else if (text.replaceAll("'", "").toLowerCase().equals("no")){
             sb.append("no\n:(");
         }
         textArea.setText(sb.toString());
    }
});

My code inserts the "yes" and "no" answers into a specific place in the JTextArea, so you may have to change it around and figure out how exactly you want it.

Note, however, that if I were programming this with Swing, I would use JLabel's for the questions and responses, and JRadioButton's for the multiple choice answers.