java - 如何使 "="符号在我的 java 计算器上工作

Question

我一直在尝试创建一个(丑陋的)计算器，但我遇到了“=”符号的问题。我知道如何将数字(字符串形式)转换为数字(整数形式)，但这里的问题主要是*/-+。当他们加入到这种情况中时，我完全不知道该怎么办。

这是计算器的 gif:http://gyazo.com/98781eaaca0b3152967e6370cad3df15

package megetenkelkalkis;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.*; 
import java.text.DecimalFormat;
import javax.swing.*; 

class Kalkulator extends JFrame{
    private String textfield = ""; 
    private String replace =""; 
    private JButton btn0 = new JButton("0");
    private JButton btn1 = new JButton("1");
    private JButton btn2 = new JButton("2"); 
    private JButton btn3 = new JButton("3"); 
    private JButton btn4 = new JButton("4"); 
    private JButton btn5 = new JButton("5");
    private JButton btn6 = new JButton("6");
    private JButton btn7 = new JButton("7"); 
    private JButton btn8 = new JButton("8"); 
    private JButton btn9 = new JButton("9");
    private JButton btnlik = new JButton("=");
    private JButton btngange = new JButton("*");
    private JButton btndele = new JButton("/");
    private JButton btnpluss = new JButton("+");
    private JButton btnminus = new JButton("-");
    private JTextField tekst = new JTextField(); 

    private JButton btndel= new JButton("DEL");

    JPanel p = new JPanel(); 
    JPanel p2 = new JPanel(); 
    JPanel p3 = new JPanel(); 

 public Kalkulator(String tittel){
 tekst.setPreferredSize(new Dimension(310,25));
 setTitle(tittel); 
 setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
 p.add(btn0);
 p.add(btn1);
 p.add(btn2);
 p.add(btn3);
 p.add(btn4);
 p.add(btn5);
 p.add(btnlik);
 p2.add(btn6);
 p2.add(btn7);
 p2.add(btn8);
 p2.add(btn9);
 p2.add(btndele); 
 p2.add(btngange);
 p2.add(btnpluss);
 p2.add(btnminus); 
 p3.add(tekst); 
 p3.add(btndel); 
 add(p, BorderLayout.SOUTH); 
 add(p2, BorderLayout.CENTER); 
 add(p3, BorderLayout.NORTH); 
 pack(); 

 Knappelytter knappelytteren = new Knappelytter(); 
 btn0.addActionListener(knappelytteren);
 btn1.addActionListener(knappelytteren);
 btn2.addActionListener(knappelytteren);
 btn3.addActionListener(knappelytteren);
 btn4.addActionListener(knappelytteren);
 btn5.addActionListener(knappelytteren);
 btn6.addActionListener(knappelytteren);
 btn7.addActionListener(knappelytteren);
 btn8.addActionListener(knappelytteren);
 btn9.addActionListener(knappelytteren);
 btnlik.addActionListener(knappelytteren);
 btndele.addActionListener(knappelytteren);
 btngange.addActionListener(knappelytteren);
 btnminus.addActionListener(knappelytteren);
 btnpluss.addActionListener(knappelytteren);
 btndel.addActionListener(knappelytteren);
 }
 class Knappelytter implements ActionListener{
 public void actionPerformed (ActionEvent  hendelse){

 JButton valgtKnapp = (JButton) hendelse.getSource(); 
 String knapp = valgtKnapp.getText(); 

 if (knapp.equals("0")){
     textfield += "0"; 
 tekst.setText(textfield);

 }else if(knapp.equals("1")){
     textfield += "1"; 
 tekst.setText(textfield);

 }else if(knapp.equals("2")){
     textfield += "2"; 
 tekst.setText(textfield);

 }else if(knapp.equals("3")){
     textfield += "3"; 
 tekst.setText(textfield);

 }else if(knapp.equals("4")){
     textfield += "4"; 
 tekst.setText(textfield);

 }else if(knapp.equals("5")){
     textfield += "5"; 
 tekst.setText(textfield);

 }else if(knapp.equals("6")){
     textfield += "6"; 
 tekst.setText(textfield);

 }else if(knapp.equals("7")){
     textfield += "7"; 
 tekst.setText(textfield);

 }else if(knapp.equals("8")){
     textfield += "8"; 
 tekst.setText(textfield);

 }else if(knapp.equals("9")){
     textfield += "9"; 
 tekst.setText(textfield);

 }else if(knapp.equals("*")){
     textfield += "*"; 
 tekst.setText(textfield);

 }else if(knapp.equals("/")){
     textfield += "/"; 
 tekst.setText(textfield);

 }else if(knapp.equals("-")){
     textfield += "-"; 
 tekst.setText(textfield);

 }else if(knapp.equals("+")){


        textfield += "+"; 
     tekst.setText(textfield);

     }else if(knapp.equals("DEL")){ 
     tekst.setText(" "); 
     textfield = " "; 

     }else if(knapp.equals("=")){ 
     else if(knapp.equals("=")){ 
/EDIT RIGHT HERE
String[] parts = textfield.split("-*/+");

for (int i = 0; i < textfield.length(); i++){
if (textfield.charAt(i) == ('-')){
String one = parts[0];
String two = parts[1]; 
int one1 = Integer.parseInt(one); 
int one2 = Integer.parseInt(two);
int one3 = one1-one2; 
String one4 = String.valueOf(one3);
tekst.setText(one4); 
     }
     }
 }

 }



public class MegetEnkelKalkis {
    public static void main(String[] args) {

        Kalkulator Skole = new Kalkulator("Kalkulator"); 
        Skole.setVisible(true);


    }

}

Answer 1

1. 获取输入
2. 将其与操作数(*、/、-、+)分开
3. 将字符串转换为 int(Integer.valueOf() 会抛出 NumberFormatException)
4. 对操作数执行 if else，然后对整数进行乘法、除法、加法或减法