Java计算器

Question

我需要有关此代码的帮助。结果将转到一个新窗口。我想要的是结果在我输入值的主窗口内。

下面的代码将有一个显示结果的弹出屏幕，而不是在零售价框中显示答案。我知道这可能是一个简单的问题或修复希望有人帮助我修复这段代码，因为我还在学习。

package com.retailcalcu;

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.JTextField;


public class Retailcalculator  extends JFrame{

  private   JPanel panel;                           // to reference a panel
  private   JLabel wholeSaleMessageLabel;       // to reference a label
  private   JLabel markupMessageLabel;          // to reference a label
  private   JLabel retailPriceLabel;            // to reference a label

  private   JTextField  wholeSalePriceField;    // to reference the Whole Sale Price Field
  private   JTextField  markUpPercentage;       // to reference the Mark Up text field
  private   JTextField  retailPrice;            // to reference the Retail Price Field
  private   JButton calculateButton;            // to reference button
  private   final   int WINDOW_WIDTH = 400;         // Window Width

  private   final int   WINDOW_HEIGHT = 150;            // Window Height


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


    public Retailcalculator(){

        // set window title
   setTitle("Retail Price Calculator");


        // set widow size

        setSize(WINDOW_WIDTH, WINDOW_HEIGHT);



        // tell what to do when the window closes

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);



      // build the panel and add it to the frame

        buildPanel();



        // add the panel to the frame's content pane

        add(panel);


        // display the window

        setVisible(true);

     }



    private void buildPanel()

    {


        // create a label for the wholesale price

        wholeSaleMessageLabel = new JLabel("Enter Wholesale Price: ");



        // create a text field 15 characters wide

        wholeSalePriceField = new JTextField(15);



        // create a label for the mark up percentage

        markupMessageLabel = new JLabel("Enter Mark Up Percentage: ");



        // create a text field 15 characters wide

        markUpPercentage = new JTextField(15);



        // create a button with the capation "Calculate Retail Price"

        calculateButton = new JButton("Calculate Retail Price");





        // add an action listener to the button

        calculateButton.addActionListener(new CalcButtonListener());





        // create a label for the retail price

        retailPriceLabel = new JLabel("The Retail Price is:  $");



        // create a text field 15 characters wide for the retail price

        retailPrice = new JTextField(15);



        // create a JPanel object and let the panel filed reference it

        panel = new JPanel();



        // add the labels, rext field and button compnenets to the panel

        panel.add(wholeSaleMessageLabel);
        panel.add(wholeSalePriceField);
        panel.add(markupMessageLabel);
        panel.add(markUpPercentage);
        panel.add(calculateButton);
        panel.add(retailPriceLabel);
        panel.add(retailPrice);

    /** calculateButton is an action listener class for the Calculate Button*/

    }

    class CalcButtonListener implements ActionListener{

        // This method executes when the user clicks on the Calculate Button

        public void actionPerformed(ActionEvent e)

        {

            String  wholesaleInput; // to hold user input for wholesale price
            String  markUpInput;        // to hold user input for mark up percentage
            double  retailPrice;        // declare retail price as a double
            double  wholePrice;         // declare wholesale prcie as a double
            double  markUp;             // declare markup percentage as a double

        // get the text entered by the user in the text field box

        wholesaleInput = wholeSalePriceField.getText();

        // convert wholesale text to double

        wholePrice = Double.parseDouble(wholesaleInput);

            // get the text entered by the user in the percentage text field

            markUpInput = markUpPercentage.getText();

            // parse out the markup percentage from the percentage text field
            markUp = Double.parseDouble(markUpInput);

            // do function to calculate retail price( wholesale * markup)

            retailPrice = ((wholePrice * markUp) * .01) + wholePrice;

            // display the results
            JOptionPane.showMessageDialog(null, retailPrice);

        }

    }
}

Answer 1

您在内部类 CalcButtonListener 中的双变量 retailPrice 是 shadowing外部类中同名的 JTextField。

因此，您必须使用:

Retailcalculator.this.retailPrice.setText(Double.toString(retailPrice));

通过将外部类中名为 retailPrice 的 JTextField 重命名为 retailPriceTextField，您可以避免混淆并简单地调用:

retailPriceTextField.setText(Double.toString(retailPrice));