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我是新來的Java，並設置自己的任務嘗試創建一個簡單的計算器（和GUI），以提高我的理解和語言的技能。計算器問題與簡單的邏輯
藉此代碼：
import java.awt.FlowLayout;
import java.io.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
public class calc extends JFrame {
public JTextField input;
public JTextField output;
public JPanel Window;
public JButton math_button[] = new JButton[5];
public JButton number_button[] = new JButton[10];
public String[] number_button_name = {"1","2","3","4","5","6","7","8","9","0"};
public String[] name = {"Add", "Mulitply", "Divide", "Subtract", "Equals"};
public JFrame frame = new JFrame();
public JPanel math_panel = new JPanel();
public JPanel number_panel = new JPanel();
public JTextField math_input = new JTextField();
boolean trrgger = false;
thehandler handler = new thehandler();
public void go()
{
for(int b=0; b<number_button.length; b++)
{
number_button[b] = new JButton(number_button_name[b]);
number_button[b].addActionListener(handler);
number_panel.add(number_button[b]);
}
for(int i=0; i<math_button.length;i++)
{
math_button[i] = new JButton(name[i]);
math_button[i].addActionListener(handler);
math_panel.add(math_button[i]);
}
frame.getContentPane().add(BorderLayout.NORTH, math_input);
frame.getContentPane().add(BorderLayout.SOUTH, math_panel);
frame.getContentPane().add(BorderLayout.CENTER, number_panel);
frame.setSize(400,400);
frame.setVisible(true);
}
//Method to handle the math and return the results of whichever 'button' was pressed
static int Math(String button_num, int first_num, int second_num)
{
int total = 0;
if(button_num == "Add")
{
total = first_num + second_num;
}
else if (button_num == "Mulitply") //multiply
{
total = first_num * second_num;
}
else if (button_num == "Divide") //divide
{
total = first_num/second_num;
}
else if (button_num == "Substract") //subtract
{
total = first_num - second_num;
}
else if (button_num == "Equals") //subtract
{
total = total;
}
return total;
}
//Action Events - Code that is triggered once the associated button is clicked
public class thehandler implements ActionListener
{
public void actionPerformed(ActionEvent event)
{
for (int h = 0; h <math_button.length; h++)
{
if(event.getSource()==math_button[h])
{
int firstn = Integer.parseInt(math_input.getText());
math_input.setText("");
int secondn = Integer.parseInt(math_input.getText());
System.out.println(calc.Math(math_button[h].getText(), firstn, secondn));
}
}
for(int n=0; n<number_button.length; n++)
{
if(event.getSource()==number_button[n])
{
String number_clicked = (number_button[n].getText());
String number = math_input.getText();
math_input.setText(number + number_clicked);
}
}
}
}
}
此代碼背後的想法是創建一個簡單的GUI，並允許用戶輸入數字的期望量，然後按「等於」按鈕以顯示結果。但是，如上所述，我在邏輯上遇到了問題。我可以從JTextField獲得第一個輸入的數字，第一個變量初始化後清除文本，但這是程序翻轉的地方。變量'second_num'作爲空白傳遞給'Math'方法（拋出錯誤），因爲這是我告訴ActionEvent要做的事情，以便更流暢地使用該程序，沒有用戶希望不得不保持清除使用計算器時的輸入框。
有人有什麼想法嗎？
謝謝
你可能也想看看這個[使用'ScriptEngine']的示例（http://stackoverflow.com/a/7441804/418556） 。 –