摄氏华氏转换Java

Question

我无法理解为什么我的应用程序无法运行。最近才开始使用编程。

我遇到的主要错误是 FahrenHandler，但我不确定该类的事件处理程序和动作侦听器应该放在哪里。

这是我的两个 java 文件，它们是 ConverterT 包的一部分：

ConverterFrame.java

package ConverterT;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author Ahmed
 */
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JOptionPane;

public class ConverterFrame extends JFrame {

    private final JTextField celciusField; // text field for celcius
    private final JLabel celciusLabel; //label for celcius
    private final JTextField fahrField; //text field for fahrenheit
    private final JLabel fahrLabel; //label for fahr

    private double celsius, fahrenheit;

    //Action Listener definition for textFields
//ConverterFrame constructor adds JTextFields to JFrame
    public ConverterFrame() {

        super("Temperature");
        setLayout(new FlowLayout());

        //construct textfield with columns
        celciusField = new JTextField(10);
        add(celciusField); //add textField1 to JFrame

        celciusLabel = new JLabel("Enter Degrees in Celcius");
        add(celciusLabel); //add textField2 to JFrame

        fahrField = new JTextField(10);
        add(fahrField); // add fahr field to JFrame

        fahrLabel = new JLabel("Enter Degrees in Fahrenheit");
        add(fahrLabel); //add fahr Label to JFrame

        //register event handlers
        CelsHandler handlerCelcius = new CelsHandler();
        celciusField.addActionListener(handlerCelcius);

        FahrenHandler handlerFahren = new FahrenHandler();
        fahrField.addActionListener(handlerFahren);

    }// end ConverterFrame constructor

    //private inner class for event handling
    private class CelsHandler implements ActionListener {

        @Override
        //process textfield events

        public void actionPerformed(ActionEvent event) {

            //user pressed enter in JTextField celciusField
            celsius = Double.parseDouble(celciusField.getText());

            //calculate the equivalent temp in fahrenheit
            fahrenheit = 9.0 / 5.0 * celsius + 32;

            //Display the result in fahrenheit field
            fahrField.setText(String.format("%.2f", fahrenheit));
        }

        FahrenHandler handlerFahren = new FahrenHandler();

        private class FahrenHandler implements ActionListener {

            @Override

            public void actionPerformed(ActionEvent event) {

                //Get the data from the text field once the user presses enter
                celsius = Double.parseDouble(celciusField.getText());

                //Calculate the equivalent temp in fahrenheit
                fahrenheit = 5.0 / 9.0 * (celsius - 32);

                //Display the result in celsiusField
                celciusField.setText(String.format("%.2f", celsius));
            }

        }

    }
}

/*       if(event.getSource() == celciusField)
 int tempFahr = (int) ((Double.parseDouble(celciusField.getText())) * 1.8 + 32);
 event.getActionCommand());

 //user pressed Enter in JTextField fahrField
 else if (event.getSource() == fahrField)
 int tempCel = (int) ((5.0/9.0 * (((Double.parseDouble(fahrField.getText())) -32))));  
 event.getActionCommand());

 //display JTextField content
 JOptionPane.showMessageDialog(ConverterFrame.this, string);
 */


ConverterTest.Java

package ConverterT;

/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */
/**
 *
 * @author Ahmed
 */
import javax.swing.JFrame;

public class ConverterTest {

    public static void main(String[] args) {

        ConverterFrame converterFrame = new ConverterFrame();
        converterFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        converterFrame.setSize(350, 100);
        converterFrame.setVisible(true);

    }

}//end class ConverterTest

Answer 1

我不确定您收到了什么错误，但您使这种方式比您需要的更困难。只需执行以下操作：

import java.util.Scanner;
import java.io.*;

public class HelloWorld{

     public static void main(String []args){
        Scanner scan = new Scanner(System.in);

        System.out.println("Enter the temperature in Fahrenheit to convert to Celsius: ");
        double fahTemp = scan.nextDouble();

        System.out.println("Enter the temperature in Celsius to convert to Fahrenheit: ");
        double celTemp = scan.nextDouble();

        double fahrenheit = (celTemp * (1.8)) + 32;
        double celsius = (fahTemp - 32) * (0.555);

        System.out.println(fahrenheit);
        System.out.println(celsius);
     }
}

Answer 2

我在本地电脑上尝试了您的代码，我看到您正试图从其外部类的构造函数创建一个内部类对象。您的代码中的问题是；

  public ConverterFrame() {

    super("Temperature");
    setLayout(new FlowLayout());

    //construct textfield with columns
    celciusField = new JTextField(10);
    add(celciusField); //add textField1 to JFrame

    celciusLabel = new JLabel("Enter Degrees in Celcius");
    add(celciusLabel); //add textField2 to JFrame

    fahrField = new JTextField(10);
    add(fahrField); // add fahr field to JFrame

    fahrLabel = new JLabel("Enter Degrees in Fahrenheit");
    add(fahrLabel); //add fahr Label to JFrame

    //register event handlers
    CelsHandler handlerCelcius = new CelsHandler();
    celciusField.addActionListener(handlerCelcius);


    ConverterFrame cf = new ConverterFrame();

    FahrenHandler handlerFahren = new FahrenHandler();
    fahrField.addActionListener(handlerFahren);

}

你应该从构造函数中移除这部分。

FahrenHandler handlerFahren = new FahrenHandler();
fahrField.addActionListener(handlerFahren);