import java.awt.*;
import java.awt.event.*;

class Calculator2 {

 public static void main(String[] args) {  
  	SimpleCalculator2 calculator = new SimpleCalculator2();
  } // main
  
} // Calculator2


// --- cut here into separate files ---

class SimpleCalculator2 extends Frame {
  
  private Panel[] p = new Panel[2];
	private Button[] buttons = new Button[5]; 
  private TextField opAField = new TextField(10);
  private TextField opBField = new TextField(10);
  private TextField resultField = new TextField(10);
  
  public SimpleCalculator2() { 
    setLayout(new GridLayout(2,1)); // override standard layout manager (-> BorderLayout)
    p[0] = new Panel(new FlowLayout(FlowLayout.CENTER, 10,15));  // operands/result fields 
    p[1] = new Panel(new BorderLayout()); // operation buttons
		    
    p[0].add(new Label("operand A"));	  // preparing upper row
    p[0].add(opAField);
    p[0].add(new Label("operand b"));
    p[0].add(opBField);
    p[0].add(new Label("result"));			
    p[0].add(resultField);

    buttons[0] = new Button("add");	  // preparing lower row						
    buttons[1] = new Button("sub");	  // operation buttons, arranged as star
    buttons[2] = new Button("mul");
    buttons[3] = new Button("int div");
    buttons[4] = new Button("real div");
    
    buttons[0].addActionListener(new AddHoerer());
    buttons[1].addActionListener(new SubHoerer());
    buttons[2].addActionListener(new MulHoerer());
    buttons[3].addActionListener(new IntDivHoerer());
    buttons[4].addActionListener(new RealDivHoerer());

    p[1].add("North", buttons[0]);
    p[1].add("East", buttons[1]);
    p[1].add("South", buttons[2]);
    p[1].add("West", buttons[3]);
    p[1].add("Center", buttons[4]);
				
    for(int i=0;i<2;i++) {	// assigning the panels to the frame
    	add(p[i]);
    }
		
    addWindowListener(new WindowAdapter() {  // register for window closing
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      } 
    });
	
    setTitle("  My Simple Calculator, V2");
    setSize(300,200);
    setVisible(true);   // show();	deprecated
    
  } // SimpleCalculator()

  class AddHoerer implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
  	int a = Integer.parseInt(opAField.getText());	
	int b = Integer.parseInt(opBField.getText());  	
	resultField.setText((a+b)+" ");
    }
  } // AddHoerer

  class SubHoerer implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
    	int a = Integer.parseInt(opAField.getText());	
	int b = Integer.parseInt(opBField.getText());  	
	resultField.setText((a-b)+" ");
    }
  } // SubHoerer

  class MulHoerer implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
    	int a = Integer.parseInt(opAField.getText());	
	int b = Integer.parseInt(opBField.getText());  	
	resultField.setText((a*b)+" ");
    }
  } // MulHoerer

  class IntDivHoerer implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
    	int a = Integer.parseInt(opAField.getText());	
	int b = Integer.parseInt(opBField.getText());  	
	resultField.setText((a/b)+" ");
    }
  } // IntDivHoerer

  class RealDivHoerer implements ActionListener { 
    public void actionPerformed(ActionEvent e) { 
    	int a = Integer.parseInt(opAField.getText());	
	double b = Integer.parseInt(opBField.getText());  	
	resultField.setText((a/b)+" ");
    }
  } // RealDivHoerer
  
} // class SimpleCalculator2