CODEWITHSUNDEEP
javatry-catch
user3773246
user3773246

Reputation:

Try and Catch for simple calculator input

This program written in java serves as a calculator. Can anyone tell me how to implement a try/catch block if the user tries to input from the result text so that I can handle incorrect workflow?

Here is the code:

    package simplecal;

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

 public class SimpleCal extends JFrame {

JTextField jftinput1, jftinput2, jftresult;
JButton jbtminus, jbtadd,jbtdivid, jbttimes;
final int JTEXT_SIZE = 5;
SimpleCal(){
    setLayout(new FlowLayout());
    jftinput1 = new JTextField(JTEXT_SIZE);
    jftinput2 = new JTextField(JTEXT_SIZE);
    jftresult = new JTextField(JTEXT_SIZE);
    add(new JLabel("Input 1: "));
    add(jftinput1);
    add(new JLabel("Input 2: "));
    add(jftinput2);
    add(new JLabel("Result "));
    add(jftresult);
    JPanel p1 = new JPanel();

    jbtminus = new JButton("Subtract");
    jbtadd = new JButton("Add");
    jbttimes = new JButton("Multiple");
    jbtdivid = new JButton("Divided");

    p1.add(jbtminus);
    jbtminus.addActionListener(new ButtonListener1());
    p1.add(jbtadd);
    jbtadd.addActionListener(new ButtonListener2());
    p1.add(jbttimes);
    jbttimes.addActionListener(new ButtonListener3());
    p1.add(jbtdivid);
    jbtdivid.addActionListener(new ButtonListener4());
    add(p1, BorderLayout.SOUTH);

}

class ButtonListener1 implements ActionListener{
    public void actionPerformed(ActionEvent e){
        double input1 = Double.parseDouble(jftinput1.getText());
        double input2 = Double.parseDouble(jftinput2.getText());

        double answer = input1 - input2;

        jftresult.setText(Double.toString(answer));
    }
}

class ButtonListener2 implements ActionListener{
    public void actionPerformed(ActionEvent e){
       double input1 = Double.parseDouble(jftinput1.getText());
        double input2 = Double.parseDouble(jftinput2.getText());

        double answer = input1 + input2;

        jftresult.setText(Double.toString(answer));
    }
}

class ButtonListener3 implements ActionListener{
    public void actionPerformed(ActionEvent e){
       double input1 = Double.parseDouble(jftinput1.getText());
        double input2 = Double.parseDouble(jftinput2.getText());

        double answer = input1 * input2;

        jftresult.setText(Double.toString(answer));
    }
}

class ButtonListener4 implements ActionListener{
    public void actionPerformed(ActionEvent e){
       double input1 = Double.parseDouble(jftinput1.getText());
        double input2 = Double.parseDouble(jftinput2.getText());

        double answer = input1 / input2;

        jftresult.setText(Double.toString(answer));
    }
}

public static void main(String[] args) {
    SimpleCal frame = new SimpleCal();
    frame.setTitle("Simple Cal");
    frame.pack();
    frame.setLocationRelativeTo(null);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setVisible(true);      
    frame.setResizable(false);
    frame.setSize(450,100);
}

}

Upvotes: 0

Views: 557

Answers (1)

Greg Hewgill
Greg Hewgill

Reputation: 994947

You don't need an exception handler for this. Simply set the field to not editable:

jftresult.setEditable(false);

See http://docs.oracle.com/javase/7/docs/api/javax/swing/text/JTextComponent.html#setEditable(boolean).

Upvotes: 1

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