重新添加/重新划分不起作用

Question

我从网上下载了一个计算器程序，然后根据需要对其进行自定义。编辑代码后，当我添加假设 2+3 时，它将显示正确答案。但在那之后，如果我除法/乘法或做任何事情，它不会显示正确的答案。

equalsButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
if (!numberCalc.getText().isEmpty())
{
int number = Integer.parseInt(numberCalc.getText());
String calc;
double calculate;
switch (calcOperation){
case 1:
calculate = currentCalc  + number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 2:
calculate = currentCalc  - number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 3:
calculate = currentCalc * number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 4:
calculate = currentCalc / number;
currentCalc = calculate;
if(currentCalc == 0){
JOptionPane.showMessageDialog(null, "You Can't divide 0! Have a good day!");
}
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 5:
numberCalc.setText(null);
break;
}
}
}
});

Answer 1

我对你的代码做了一些更改。这个应该有效。它抛出了一个异常，因为当您将上一个操作的双精度类型输出用于下一个操作时，您正在使用 Integer.parseInt(..( 解析双精度值。

package com.example;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Container;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import java.io.File;
import java.util.*;
import javax.imageio.ImageIO;
import javax.swing.*;

public class SimpleCalc implements ActionListener{
JFrame guiFrame;
JPanel buttonPanel;
JTextField numberCalc;
int calcOperation = 0;
double currentCalc;
//Note: Typically the main method will be in a
//separate class. As this is a simple one class
//example it's all in the one class.
public static void main(String[] args) {
//Use the event dispatch thread for Swing components
EventQueue.invokeLater(new Runnable()
{
@Override
public void run()
{
new SimpleCalc();         
}
});
}
public SimpleCalc()
{
guiFrame = new JFrame();
//make sure the program exits when the frame closes
guiFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
guiFrame.setTitle("Calculator Project");
guiFrame.setSize(400,400);
//This will center the JFrame in the middle of the screen
guiFrame.setLocationRelativeTo(null);
numberCalc = new JTextField();
numberCalc.setHorizontalAlignment(JTextField.RIGHT);
numberCalc.setLayout(null);
numberCalc.setSize(100,400);
numberCalc.setEditable(false);
guiFrame.add(numberCalc, BorderLayout.NORTH);
buttonPanel = new JPanel();

buttonPanel.setLayout(new GridLayout(4,4));   
guiFrame.add(buttonPanel, BorderLayout.CENTER);
//Add the number buttons
for (int i=0;i<10;i++)
{
addButton(buttonPanel, String.valueOf(i));
}
JButton clrButton = new JButton("C");
clrButton.setActionCommand("C");
OperatorAction clrAction = new OperatorAction(5);
clrButton.addActionListener(clrAction);
JButton subsButton = new JButton("*");
subsButton.setActionCommand("*");
OperatorAction subsAction = new OperatorAction(3);
subsButton.addActionListener(subsAction);
JButton divideButton = new JButton("/");
divideButton.setActionCommand("/");
OperatorAction divideAction = new OperatorAction(4);
divideButton.addActionListener(divideAction);

JButton addButton = new JButton("+");
addButton.setActionCommand("+");
OperatorAction subAction = new OperatorAction(1);
addButton.addActionListener(subAction);
JButton subButton = new JButton("-");
subButton.setActionCommand("-");
OperatorAction addAction = new OperatorAction(2);
subButton.addActionListener(addAction);
JButton equalsButton = new JButton("=");
equalsButton.setActionCommand("=");
equalsButton.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent event)
{
if (!numberCalc.getText().isEmpty())
{
int number = Integer.parseInt(numberCalc.getText());
String calc;
double calculate;
switch (calcOperation){
case 1:
calculate = currentCalc  + number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 2:
calculate = currentCalc  - number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 3:
calculate = currentCalc * number;
currentCalc = calculate;
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 4:
calculate = currentCalc / number;
currentCalc = calculate;
if(currentCalc == 0){
JOptionPane.showMessageDialog(null, "You Can't  divide 0! Have a good day!");
}
calc = String.valueOf(calculate);
numberCalc.setText(calc);
break;
case 5:
numberCalc.setText(null);
break;
}
}


}
});
buttonPanel.add(addButton);
buttonPanel.add(subButton);
buttonPanel.add(subsButton);
buttonPanel.add(divideButton);
buttonPanel.add(equalsButton);
buttonPanel.add(clrButton);
guiFrame.setVisible(true);  
}
//All the buttons are following the same pattern
//so create them all in one place.
private void addButton(Container parent, String name)
{
JButton but = new JButton(name);
but.setActionCommand(name);
but.addActionListener(this);
parent.add(but);
}

@Override
public void actionPerformed(ActionEvent event)
{
//get the Action Command text from the button
String action = event.getActionCommand();
//set the text using the Action Command text
numberCalc.setText(action);       
}

private class OperatorAction implements ActionListener
{
private int operator;
public OperatorAction(int operation)
{
operator = operation;
}
public void actionPerformed(ActionEvent event)
{
currentCalc = Double.parseDouble(numberCalc.getText()); 
calcOperation = operator;
}
}
}