Расчеты в JTextArea

Question

С приложением, которое я только что создал на работе, мой босс оказывает на меня давление, чтобы добавить простой инструмент калькулятора, чтобы клиент получил «больше за свои деньги». Я создал калькулятор, но я не могу понять, как выполнять вычисления. Вот мой код:

package Interface; 

import java.awt.BorderLayout; 
import java.awt.Dimension; 
import java.awt.Font; 
import java.awt.event.ActionEvent; 
import java.awt.event.ActionListener; 

import javax.swing.JButton; 
import javax.swing.JFrame; 
import javax.swing.JPanel; 
import javax.swing.JTextArea; 

public class GUI { 

public static void main(String[] args) { 

    JPanel Panel = new JPanel(); 

    JFrame Frame = new JFrame("Calculator"); 

    Font ButtonFont = new Font("Font",1,30); 

    final JTextArea Print = new JTextArea(1,27); 
    Panel.add(Print); 

    JButton Clear = new JButton("C"); 
    Clear.setPreferredSize(new Dimension(70,70)); 
    Clear.setFont(ButtonFont); 
    Panel.add(Clear); 
    Clear.addActionListener(new ActionListener() { 
     public void actionPerformed(ActionEvent e) { 
      Print.setText(""); 
     } 
    }); 

    JButton PosNeg = new JButton("+/-"); 
    PosNeg.setPreferredSize(new Dimension(70,70)); 
    PosNeg.setFont(ButtonFont); 
    Panel.add(PosNeg); 

    JButton Percent = new JButton("%"); 
    Percent.setPreferredSize(new Dimension(70,70)); 
    Percent.setFont(ButtonFont); 
    Panel.add(Percent); 

    JButton Divide = new JButton("/"); 
    Divide.setPreferredSize(new Dimension(70,70)); 
    Divide.setFont(ButtonFont); 
    Panel.add(Divide); 

    JButton Seven = new JButton("7"); 
    Seven.setPreferredSize(new Dimension(70,70)); 
    Seven.setFont(ButtonFont); 
    Panel.add(Seven); 

    JButton Eight = new JButton("8"); 
    Eight.setPreferredSize(new Dimension(70,70)); 
    Eight.setFont(ButtonFont); 
    Panel.add(Eight); 

    JButton Nine = new JButton("9"); 
    Nine.setPreferredSize(new Dimension(70,70)); 
    Nine.setFont(ButtonFont); 
    Panel.add(Nine); 

    JButton Multiply = new JButton("X"); 
    Multiply.setPreferredSize(new Dimension(70,70)); 
    Multiply.setFont(ButtonFont); 
    Panel.add(Multiply); 

    JButton Four = new JButton("4"); 
    Four.setPreferredSize(new Dimension(70,70)); 
    Four.setFont(ButtonFont); 
    Panel.add(Four); 

    JButton Five = new JButton("5"); 
    Five.setPreferredSize(new Dimension(70,70)); 
    Five.setFont(ButtonFont); 
    Panel.add(Five); 

    JButton Six = new JButton("6"); 
    Six.setPreferredSize(new Dimension(70,70)); 
    Six.setFont(ButtonFont); 
    Panel.add(Six); 

    JButton Subtract = new JButton("-"); 
    Subtract.setPreferredSize(new Dimension(70,70)); 
    Subtract.setFont(ButtonFont); 
    Panel.add(Subtract); 

    JButton One = new JButton("1"); 
    One.setPreferredSize(new Dimension(70,70)); 
    One.setFont(ButtonFont); 
    Panel.add(One); 

    JButton Two = new JButton("2"); 
    Two.setPreferredSize(new Dimension(70,70)); 
    Two.setFont(ButtonFont); 
    Panel.add(Two); 

    JButton Three = new JButton("3"); 
    Three.setPreferredSize(new Dimension(70,70)); 
    Three.setFont(ButtonFont); 
    Panel.add(Three); 

    JButton Add = new JButton("+"); 
    Add.setPreferredSize(new Dimension(70,70)); 
    Add.setFont(ButtonFont); 
    Panel.add(Add); 

    JButton Dec = new JButton("."); 
    Dec.setPreferredSize(new Dimension(70,70)); 
    Dec.setFont(ButtonFont); 
    Panel.add(Dec); 

    JButton Zero = new JButton("0"); 
    Zero.setPreferredSize(new Dimension(70,70)); 
    Zero.setFont(ButtonFont); 
    Panel.add(Zero); 

    JButton Root = new JButton("\\/"); 
    Root.setPreferredSize(new Dimension(70,70)); 
    Root.setFont(ButtonFont); 
    Panel.add(Root); 

    final JButton Equal = new JButton("="); 
    Equal.setPreferredSize(new Dimension(70,70)); 
    Equal.setFont(ButtonFont); 
    Panel.add(Equal); 

    Frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
    Frame.getContentPane().add(Panel, BorderLayout.CENTER); 
    Frame.pack(); 
    Frame.setVisible(true); 
    Frame.setLocationRelativeTo(null); 
    Frame.setResizable(false); 
    Frame.setSize(350,450); 

} 
} 

Answer 1

Во-первых, я хотел бы предложить вам использовать JTextField вместо JTextArea.

Во-вторых, для простого расчета вам нужно добавить ActionListener() каждой кнопке. Затем вы можете добавить результат к JTextField на actionListener кнопки оператора (+/-/* //).

Посмотрите на этот пример примера.

import java.awt.*; 
import java.awt.event.*; 
import javax.swing.*; 
public class Carl extends JFrame{ 
    JTextField text1= new JTextField(); 
    JLabel label1= new JLabel (" "); 
    JButton button1= new JButton ("1"); 
    JButton button2= new JButton ("2"); 
    JButton button3= new JButton ("3"); 
    JButton button4= new JButton ("4"); 
    JButton button5= new JButton ("5"); 
    JButton button6= new JButton ("6"); 
    JButton button7= new JButton ("7"); 
    JButton button8= new JButton ("8"); 
    JButton button9= new JButton ("9"); 
    JButton button10= new JButton ("0"); 
    JButton button11= new JButton ("+"); 
    JButton button12= new JButton ("-"); 
    JButton button13= new JButton ("*"); 
    JButton button14= new JButton ("/"); 
    JButton button15= new JButton ("="); 
    JButton button16= new JButton ("C"); 
    JLabel blank1 = new JLabel(""); 
    JLabel blank2 = new JLabel(""); 
    JLabel blank3 = new JLabel(""); 
    JLabel blank4 = new JLabel(""); 
    Font times= new Font ("Times New Roman", Font.BOLD, 14); 
    int operation1; 
    int operation2; 
    int operation3; 
    int operation4; 
    String n1,n2; 
    JPanel p1 = new JPanel(); 
    JPanel p2 = new JPanel(); 

public Carl(){ 
     setResizable(true); 
     setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); 
     setTitle("Calculator"); 
     setSize(600,600);   
     button1.setForeground(Color.BLACK); 
     button2.setForeground(Color.BLACK); 
     button3.setForeground(Color.BLACK); 
     button4.setForeground(Color.BLACK); 
     button5.setForeground(Color.BLACK); 
     button6.setForeground(Color.BLACK); 
     button7.setForeground(Color.BLACK); 
     button8.setForeground(Color.BLACK); 
     button9.setForeground(Color.BLACK); 
     button10.setForeground(Color.BLACK); 
     button11.setForeground(Color.BLACK); 
     button12.setForeground(Color.BLACK); 
     button13.setForeground(Color.BLACK); 
     button14.setForeground(Color.BLACK); 
     button15.setForeground(Color.BLACK); 
     button16.setForeground(Color.BLACK); 
     button1.setBackground(Color.YELLOW); 
     button2.setBackground(Color.YELLOW); 
     button3.setBackground(Color.YELLOW); 
     button4.setBackground(Color.YELLOW); 
     button5.setBackground(Color.YELLOW); 
     button6.setBackground(Color.YELLOW); 
     button7.setBackground(Color.YELLOW); 
     button8.setBackground(Color.YELLOW); 
     button9.setBackground(Color.YELLOW); 
     button10.setBackground(Color.YELLOW); 
     button11.setBackground(Color.YELLOW); 
     button12.setBackground(Color.YELLOW); 
     button13.setBackground(Color.YELLOW); 
     button14.setBackground(Color.YELLOW); 
     button15.setBackground(Color.YELLOW); 
     button16.setBackground(Color.YELLOW); 
     button1.setToolTipText ("one"); 
     button2.setToolTipText ("two"); 
     button3.setToolTipText ("three"); 
     button4.setToolTipText ("four"); 
     button5.setToolTipText ("five"); 
     button6.setToolTipText ("six"); 
     button7.setToolTipText ("seven"); 
     button8.setToolTipText ("eight"); 
     button9.setToolTipText ("nine"); 
     button10.setToolTipText ("zero"); 
     button11.setToolTipText ("addition"); 
     button12.setToolTipText ("subtraction"); 
     button13.setToolTipText ("multiplication"); 
     button14.setToolTipText ("division"); 
     button15.setToolTipText ("equal"); 
     button16.setToolTipText ("clear"); 
     button1.setFont(times); 
     button2.setFont(times); 
     button3.setFont(times); 
     button4.setFont(times); 
     button5.setFont(times); 
     button6.setFont(times); 
     button7.setFont(times); 
     button8.setFont(times); 
     button9.setFont(times); 
     button10.setFont(times); 
     button11.setFont(times); 
     button12.setFont(times); 
     button13.setFont(times); 
     button14.setFont(times); 
     button15.setFont(times); 
     button16.setFont(times); 
     label1.setFont(times); 
     setLayout(new BorderLayout()); 
     p1.setLayout(new GridLayout(6,3,2,2)); 
     p1.add(p2,BorderLayout.CENTER); 
     p1.add(label1); 
     p1.add(text1); 
     p1.add(blank3); 
     p1.add(button7); 
     p1.add(button8); 
     p1.add(button9); 
     p1.add(button11); 
     p1.add(button4); 
     p1.add(button5); 
     p1.add(button6); 
     p1.add(button12); 
     p1.add(button1); 
     p1.add(button2); 
     p1.add(button3); 
     p1.add(button13); 
     p1.add(button10); 
     p1.add(button16); 
     p1.add(button15); 
     p1.add(button14); 
add(p1,BorderLayout.CENTER); 

button1.addActionListener(new Listener1()); 
     button2.addActionListener(new Listener2()); 
     button3.addActionListener(new Listener3()); 
     button4.addActionListener(new Listener4()); 
     button5.addActionListener(new Listener5()); 
     button6.addActionListener(new Listener6()); 
     button7.addActionListener(new Listener7()); 
     button8.addActionListener(new Listener8()); 
     button9.addActionListener(new Listener9()); 
     button10.addActionListener(new Listener0()); 
     button11.addActionListener(new ListenerAdd()); 
     button12.addActionListener(new ListenerSub()); 
     button13.addActionListener(new ListenerMul()); 
     button14.addActionListener(new ListenerDiv()); 
     button15.addActionListener(new ListenerEqual()); 
     button16.addActionListener(new ListenerClear()); 
setVisible(true); 

} 

    private class Listener1 implements ActionListener{ 
     public void actionPerformed (ActionEvent a){ 
      n1= text1.getText();     
      text1.setText (n1+"1"); 
     } 
    } 


private class Listener2 implements ActionListener{ 
     public void actionPerformed (ActionEvent b){ 
      n1= text1.getText(); 
      text1.setText (n1+"2"); 
     } 
    } 
    private class Listener3 implements ActionListener{ 
     public void actionPerformed (ActionEvent c){ 
      n1= text1.getText(); 
      text1.setText (n1+"3"); 
     } 
    } 
    private class Listener4 implements ActionListener{ 
     public void actionPerformed (ActionEvent d){ 
      n1= text1.getText(); 
      text1.setText (n1+"4"); 
     } 
    } 
    private class Listener5 implements ActionListener{ 
     public void actionPerformed (ActionEvent e){ 
      n1= text1.getText(); 
      text1.setText (n1+"5"); 
     } 
    } 

private class Listener6 implements ActionListener{ 
     public void actionPerformed (ActionEvent f){ 
      n1= text1.getText(); 
      text1.setText (n1+"6"); 
     } 
    } 
    private class Listener7 implements ActionListener{ 
     public void actionPerformed (ActionEvent g){ 
      n1= text1.getText(); 
      text1.setText (n1+"7"); 
     } 
    } 
    private class Listener8 implements ActionListener{ 
     public void actionPerformed (ActionEvent h){ 
      n1= text1.getText(); 
      text1.setText (n1+"8"); 
     } 
    } 
    private class Listener9 implements ActionListener{ 
     public void actionPerformed (ActionEvent i){ 
      n1= text1.getText(); 
      text1.setText (n1+"9"); 
     } 
    } 

private class Listener0 implements ActionListener{ 
     public void actionPerformed (ActionEvent j){ 
      n1= text1.getText(); 
      text1.setText (n1+"0"); 
     } 
    } 
    private class ListenerAdd implements ActionListener{ 
     public void actionPerformed (ActionEvent k){ 
      n2= text1.getText(); 
      operation1=1; 
      text1.setText (""); 
     } 
    } 
    private class ListenerSub implements ActionListener{ 
     public void actionPerformed (ActionEvent l){ 
      n2= text1.getText(); 
      operation2=2; 
      text1.setText (""); 
     } 
    } 

private class ListenerMul implements ActionListener{ 
     public void actionPerformed (ActionEvent m){ 
      n2= text1.getText(); 
      operation3=3; 
      text1.setText (""); 
     } 
    } 

    private class ListenerDiv implements ActionListener{ 
     public void actionPerformed (ActionEvent n){ 
      n2= text1.getText(); 
      operation4=4; 
      text1.setText ("");   
     } 
    } 
    private class ListenerEqual implements ActionListener{ 
     public void actionPerformed (ActionEvent o){ 
      if(operation1==1){ 
       int a=Integer.parseInt(n2); 
       int b=Integer.parseInt(text1.getText()); 
       int sum = (a + b); 
       String sum1 = Integer.toString(sum); 
       text1.setText(sum1); 
      } 

else{ 
      text1.getText(); 
      } 
      if(operation2==2){ 
       int a=Integer.parseInt(n2); 
       int b=Integer.parseInt(text1.getText()); 
       int dif = (a - b); 
       String dif1 = Integer.toString(dif); 
       text1.setText(dif1); 
      } 
      else{ 
      text1.getText(); 
      } 
      if(operation3==3){ 
       int a=Integer.parseInt(n2); 
       int b=Integer.parseInt(text1.getText()); 
       int product = (a * b); 
       String product1 = Integer.toString(product); 
       text1.setText(product1); 
      } 

else{ 
      text1.getText(); 
      } 
      if(operation4==4){ 
       double a=Double.parseDouble(n2); 
       double b=Double.parseDouble(text1.getText()); 
       double quo = (a/b); 
       String quo1 = Double.toString(quo); 
       text1.setText(quo1); 
      } 
      else{ 
      text1.getText(); 
      }  
     } 
    } 
    private class ListenerClear implements ActionListener{ 
     public void actionPerformed (ActionEvent p){ 
      text1.setText(""); 
     } 
    } 
public static void main(String[]args){ 
    Carl frame= new Carl();  
} 
}