Simple addition calculator

Simple addition calculator

package Calculator;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class demo02 {
    
    public static void main(String[] args) {
    
        new Calculator();      
    }
}
// Calculator class 
class Calculator extends Frame {
    
    public Calculator()  {
    
        
        TextField textField1=new TextField(10);// Number of characters 
        TextField textField2=new TextField(10);// Number of characters 
        TextField textField3=new TextField(20);// Number of characters 

        Button button = new Button("=");
        button.addActionListener(new MyCalculator(textField1,textField2,textField3));

        Label label = new Label("+");

        setLayout(new FlowLayout());
        add(textField1);
        add(label);
        add(textField2);
        add(button);
        add(textField3);

        pack();
        setVisible(true);
    }
}
// Monitor class 
class MyCalculator implements ActionListener{
    
    private TextField num1,num2,num3;
    // I don't know why I use the constructor to get these three numbers 
    public MyCalculator(TextField num1,TextField num2,TextField  num3) {
    
        this.num1=num1;
        this.num2=num2;
        this.num3=num3;
    }


    @Override
    public void actionPerformed(ActionEvent e) {
    

        //1, Get the addend and the addend 
        // take String Type into int type 
        int n1=Integer.parseInt(num1.getText());
        int n2=Integer.parseInt(num2.getText());

        //2, Take this value + After operation , Put it in the third box 
        num3.setText(""+(n1+n2));
        //3, Clear the first two numbers 
        num1.setText("");
        num2.setText("");
    }
}

Simple addition calculator （ Access directly with inner classes ）

// If you don't finish writing, you will report a null pointer exception , It won't be solved for the time being 
package Calculator;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

public class demo02 {
    
    public static void main(String[] args) {
    
        new Calculator().loadFrame();
    }
}


// Calculator class 
class Calculator extends Frame {
    
    // attribute 
    TextField num1,num2,num3;
    // Method 
    public void loadFrame(){
    

        num1=new TextField(10);
        num2=new TextField(10);
        num3=new TextField(20);
        
        Button button=new Button("=");
      // button.addActionListener(new MyCalculator(num1,num2,num3));
        button.addActionListener(new MyActionListener());
        
        Label label=new Label();
        setLayout(new FlowLayout());
        add(num1);
        add(label);
        add(num2);
        add(button);
        add(num3);
        pack();
        setVisible(true);
    }

    // Monitor class 
  private   class MyCalculator implements ActionListener{
    


        @Override
        public void actionPerformed(ActionEvent e) {
    

            //1, Get the addend and the addend 
            // take String Type into int type 
            //2, Take this value + After operation , Put it in the third box 
            //3, Clear the first two numbers 

            int n1=Integer.parseInt(num1.getText());
            int n2=Integer.parseInt(num2.getText());
            num3.setText(""+(n1+n2));
            num1.setText("");
            num2.setText("");
        }
    }
}

Type conversion String Convert to Int

Transformation format ：
Integer.parseInt（） You can put String Type conversion to Int
Usage method ： int n1=Integer.parseInt(num1.getText());