如何从同一文本字段中获得两个值？

Question

I am new to GUI and trying to make a calculator in JFrame but whenever I perform the addition operation it says that the string is empty.If I remove "jTextField1.setText("");" part it works fine but the previous text is still on the text field. Is there a way I could create another instance of text field or something like that to accommodate the second string?

 private void jButton10ActionPerformed(java.awt.event.ActionEvent evt) {                                          
        a=Float.parseFloat(jTextField1.getText());
         jTextField1.setText("");
        b=Float.parseFloat(jTextField1.getText());
        res=a+b; 

    }  

Answer 1

I think you need this code.

enter code here

import java.awt.*;
import javax.swing.*;

class Calculation_ActionEvent extends JFrame implements ActionListener {
JFrame f;
JLabel l;
JTextField tf1, tf3;
JButton b1, b2, b3, b4, b5, b6;

Calculation_ActionEvent(String s) {
    f = new JFrame(s);
    f.setLayout(null);
    l = new JLabel("Enter two numbers : ");
    tf1 = new JTextField();
    // tf2 = new JTextField();
    tf3 = new JTextField();
    b1 = new JButton("+");
    b2 = new JButton("-");
    b3 = new JButton("*");
    b4 = new JButton("/");
    b5 = new JButton("equals");
    b6 = new JButton("C");
    f.add(l);
    f.add(tf1);
    f.add(tf3);
    f.add(b1);
    f.add(b2);
    f.add(b3);
    f.add(b4);
    f.add(b5);
    f.add(b6);
    tf1.setBounds(160, 100, 250, 30);
    // tf2.setBounds(320,100,50,30);
    tf3.setBounds(250, 420, 50, 30);
    b1.setBounds(250, 180, 50, 30);
    b2.setBounds(350, 260, 50, 30);
    b3.setBounds(150, 260, 50, 30);
    b4.setBounds(250, 340, 50, 30);
    b5.setBounds(230, 260, 90, 30);
    b6.setBounds(420, 100, 50, 30);
    b1.addActionListener(this);
    b2.addActionListener(this);
    b3.addActionListener(this);
    b4.addActionListener(this);
    b5.addActionListener(this);
    b6.addActionListener(this);
    f.setSize(550, 550);
    f.setVisible(true);
}

int total = 0;
String lastAction = "";

public void actionPerformed(ActionEvent e) {
    int num = 0;
    try {
        num = Integer.parseInt(tf1.getText());
    } catch(NumberFormatException ex) {}
    String s1 = e.getActionCommand();
    if (s1.equals("C")) {
        tf1.setText("");
        tf3.setText("0");
        tf1.requestFocus();
        total = 0;
    } else if (s1.equals("equals")) {
        tf3.setText(String.valueOf(calc(total, lastAction, num)));
        tf1.setText("");
        tf1.requestFocus();
        total = 0;
    } else {
        total = total==0 ? num : calc(total, lastAction, num);
        tf3.setText(String.valueOf(total));
        tf1.setText("");
        tf1.requestFocus();
        lastAction = s1;
    }
}

private int calc(int num1, String action, int num2) {
    switch (action) {
    case "+":
        return num1 + num2;
    case "-":
        return num1 - num2;
    case "*":
        return num1 * num2;
    case "/":
        return num1 / num2;
    default:
        return num1;
    }
}

public static void main(String... s) {
    new Calculation_ActionEvent("Calculator");
}

}