I am constructing a simple modified Subtraction-only calculator where z = x - y. I have created 3 textfields: x, y, and z. The user will input the value using the keypad (buttons) I have designed for the x and y.
Just by looking at the code below, there are couple of issues right away.
1) The x textfield only accepts one digit. (I want it to accept up to 3 digits). Any suggestions on how I can amend the else if statement to incorporate that?
2) When I am done with the x textfield, I want to do it with the same with the y textfield. But the buttons are strictly allocated to the x textfield. It would be inefficient to make one more keypad just for y textfield. So how can I switch between x and y text field. Is there some code where if the user has the cursor on the x text field, the keypad is reserved for that x text field and if the user changes to the y textfield, the keypad can be used for the y then.
3) And once user hits enter, its a simple operation z = x - y . Which should be easy to implement. i.e. Convert the strings to integers etc. and perform the difference.
Thank you all in advance!
import javax.swing.*;
import java.awt.event.*;
import java.io.*;
import javax.swing.event.*;
import java.awt.*;
import java.applet.*;
public class EmbeddedMain extends JFrame
{
private JTextField x,y,z;
private JButton button1, button2, button3, button4, button5, button6, button7, button8, button9, button0, buttonR, buttonE;
public static void main (String[] args)
{
EmbeddedMain em = new EmbeddedMain();
}
public EmbeddedMain() //constructor begins, method for embedded main class
{
setTitle("Subtraction");
setSize(450,350);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
setLayout(new GridLayout(4,5,3,3));
setVisible(true);
button1= new JButton("7");
button2= new JButton("8");
button3= new JButton("9");
button4= new JButton("4");
button5= new JButton("5");
button6= new JButton("6");
button7= new JButton("1");
button8= new JButton("2");
button9= new JButton("3");
button0= new JButton("0");
buttonR= new JButton("Reset");
buttonE= new JButton("Enter");
x = new JTextField(" ");
y = new JTextField(" ");
z = new JTextField(" ");
z.setEditable(false);
add(button1);
add(button2);
add(button3);
add(new JLabel(" x:"));
add(x);
add(button4);
add(button5);
add(button6);
add(new JLabel(" y:"));
add(y);
add(button7);
add(button8);
add(button9);
add(new JLabel(" z:"));
add(z);
add(buttonR);
add(button0);
add(buttonE);
thehandler handler = new thehandler();
button1.addActionListener(handler);
button2.addActionListener(handler);
button3.addActionListener(handler);
button4.addActionListener(handler);
button5.addActionListener(handler);
button6.addActionListener(handler);
button7.addActionListener(handler);
button8.addActionListener(handler);
button9.addActionListener(handler);
button0.addActionListener(handler);
buttonR.addActionListener(handler);
buttonE.addActionListener(handler);
}
//building class inside class
private class thehandler implements ActionListener{
public void actionPerformed(ActionEvent event){
if(event.getSource()== button1)
x.setText("7");
else if (event.getSource()== button2)
x.setText("8");
else if (event.getSource()== button3)
x.setText("9");
else if (event.getSource()== button4)
x.setText("4");
else if (event.getSource()== button5)
x.setText("5");
else if (event.getSource()== button6)
x.setText("6");
else if (event.getSource()== button7)
x.setText("1");
else if (event.getSource()== button8)
x.setText("2");
else if (event.getSource()== button9)
x.setText("3");
else if (event.getSource()== button0)
x.setText("0");
else if (event.getSource()== buttonR)
x.setText(" ");
}
}
}
You can add a MouseListener to the textfields so you know when the user has switched from x to y and vice versa:
private JTextField selected;
selected = x;
x.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
selected = x;
}
});
y.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
selected = y;
}
});
To do the subtraction, convert the text present in x and y to ints and subtract. You can refactor your actionPerformed to:
public void actionPerformed(ActionEvent event) {
String s = selected.getText();
if (event.getSource() == buttonR) {
x.setText("");
y.setText("");
z.setText("");
} else if (event.getSource() == buttonE) {
int result = Integer.parseInt(x.getText()) - Integer.parseInt(y.getText());
z.setText(String.valueOf(result));
} else {
String command = event.getActionCommand();
selected.setText(s + command);
}
}