Calculator Program - class, interface, or enum expected

Question

locked_twilight 0 Newbie Poster

14 Years Ago

package MyJava; //change package name according to what the name of the package
                    //the class would be installed to

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

public class [B]Calculator[/B] extends JFrame implements ActionListener{

    private JTextField displayText = new JTextField(30);
    private JButton[] button = new JButton[16];

    private String[] keys = {"7", "8", "9", "/",
                             "4", "5", "6","*", 
                             "1", "2", "3", "-",
                              "0", "C", "=", "+"};

    private String numStr1 = "";
    private String numStr2 = "";

    private char op;
    private boolean firstInput = true;

    public Calculator () {
        setTitle("Calculator");
        setSize(230, 200);
        Container pane = getContentPane();

        pane.setLayout(null);

        displayText.setSize(200, 30);
        displayText.setLocation(10,10);
        pane.add(displayText);

        int x, y;
        x = 10;
        y = 40;

        for (int ind = 0; ind < 16; ind++) {
            button[ind] = new JButton(keys[ind]);
            button[ind].addActionListener(this);
            button[ind].setSize(50, 30);
            button[ind].setLocation(x, y);
            pane.add(button[ind]);
            x = x + 50;

            if ((ind + 1) % 4 == 0) {
                x = 10;
                y = y +30;
            }
        }

    this.addWindowListener(new Window Adapter()) {
        public void windowClosing(WindowEvent e) {
            System.exit(0);
        }
    }
};

    setVisible(true);

}

public void actionPerformed(ActionEvent e) {
    String resultStr;

    String str = String.valueOf(e.getActionCommand());

    char ch = str.charAt(0);

    switch (ch) {
        case '0' :
        case '1' :
        case '2' :
        case '3' :
        case '4' :
        case '5' :
        case '6' :
        case '7' :
        case '8' :
        case '9' :
            if (firstInput) {
                numStr1 = numStr1 + ch;
                displayText.setText(numStr1);
            }
            else {
                numStr2 = numStr2 + ch;
                displayText.setText(numStr2);
            }
            break;

        case '+' :
        case '-' :
        case '*' :
        case '/' :
            op = ch;
            firstInput = false;
            break;
        case '=' :
            resultStr = evauate();
            displayText.setText(resultStr);
            numStr1 = resultStr;
            numStr2 = "";
            firstInput = false;
            break;

        case 'C' :
            displayText.setText("");
            numStr1 = "";
            numStr2 = "";
            firstInput = true;
    }
}

private String evaluate() {
    final char beep = '\u0007';

    try {
        int num1 = Integer.parseInt(numStr1);
        int num2 = Integer.parseInt(numStr2);
        int result = 0;

        switch (op) {
            case '+':
                result = num1 + num2;
                break;
            case '-':
                result = num1 - num2;
                break;
            case '*':
                result = num1 * num2;
                break;
            case '/':
                result = num1 + num2;
        }

        return String.valueOf(result);
    }
    catch (ArithmeticException e) {
        System.out.print(beep);
        return: "E R R O R: " + e.getMessage();
    }
    catch (NumberFormatException e) {
        System.out.print(beep);

        if (numStr1.equals(""))
            return "E R R O R : Invalid First Number";
        else
            return "E R R O R: Invalid Second Number";
    }
    catch (Exception e) {
        System.out.print(beep);
        return "E R R O R";
    }


public static void main(String[] args) {
    Calculator C = new Calculator();
}

----------
class, interface, or enum expected beginning at lines char ch = str.charAt(0); down to 
    catch (Exception e) {
        System.out.print(beep);
        return "E R R O R";
    }

Please help me, I'm just a beginner in Java.
Thank you.

java

Edited 11 Years Ago by Dani because: Formatting fixed

4 Contributors
7 Replies
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Latest Post 14 Years Ago Latest Post by locked_twilight

All 7 Replies

JamesCherrill 4,733 Most Valuable Poster

14 Years Ago

Probably one too many } brackets. Repost code with code=java tags and corect indentation.

di2daer 12 Junior Poster in Training

14 Years Ago

Hi,

you should really use code tags when posting code, it is way to hard to read without...
Anyway, the errors I've spotted are:

private String[] keys = ("7", "8", "9", "/",
"4", "5", "6","*",
"1", "2", "3", "-",
"0", "C", "=", "+");

When initializing arrays you should use '{' '}' not '(' ')'

private String[] keys = {"7", "8", "9", "/",
"4", "5", "6","*",
"1", "2", "3", "-",
"0", "C", "=", "+"};

Also:

this.addWindowListener(new Window Adapter()) {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
}
};

WindowAdapter should not be separated with a space. Also, when you write inner anonymous classes like this, you must write the whole class within the parenthesis of the method call.
this.addWindowListener(new Window Adapter()) <-- this should be moved to the end of the method call.

I also noticed that there is an ':' after a return statement in a catch clause.

There might be more, but I hope this should get you going
Good luck

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peter_budo 2,532 Code tags enforcer Team Colleague Featured Poster · Answer 1 · 2009-10-11T20:29:09+00:00

You need to pay closer attention to opening and closing of brackets. See bellow code (the code still will not compile and throw some errors which you need to solve)

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

public class Calculator extends JFrame implements ActionListener{

    private JTextField displayText = new JTextField(30);
    private JButton[] button = new JButton[16];

    private String[] keys = {"7", "8", "9", "/",
    "4", "5", "6","*",
    "1", "2", "3", "-",
    "0", "C", "=", "+"};

    private String numStr1 = "";
    private String numStr2 = "";

    private char op;
    private boolean firstInput = true;

    public Calculator () {
        setTitle("Calculator");
        setSize(230, 200);
        Container pane = getContentPane();

        pane.setLayout(null);

        displayText.setSize(200, 30);
        displayText.setLocation(10,10);
        pane.add(displayText);

        int x, y;
        x = 10;
        y = 40;

        for (int ind = 0; ind < 16; ind++) {
            button[ind] = new JButton(keys[ind]);
            button[ind].addActionListener(this);
            button[ind].setSize(50, 30);
            button[ind].setLocation(x, y);
            pane.add(button[ind]);
            x = x + 50;

            if ((ind + 1) % 4 == 0) {
                x = 10;
                y = y +30;
            }
        }

        this.addWindowListener(new Window Adapter()) {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        }
    };

    setVisible(true);

//}

    public void actionPerformed(ActionEvent e) {
        String resultStr;

        String str = String.valueOf(e.getActionCommand());

        char ch = str.charAt(0);

        switch (ch) {
        case '0' :
        case '1' :
        case '2' :
        case '3' :
        case '4' :
        case '5' :
        case '6' :
        case '7' :
        case '8' :
        case '9' :
        if (firstInput) {
        numStr1 = numStr1 + ch;
        displayText.setText(numStr1);
        }
        else {
        numStr2 = numStr2 + ch;
        displayText.setText(numStr2);
        }
        break;

        case '+' :
        case '-' :
        case '*' :
        case '/' :
        op = ch;
        firstInput = false;
        break;
        case '=' :
        resultStr = evauate();
        displayText.setText(resultStr);
        numStr1 = resultStr;
        numStr2 = "";
        firstInput = false;
        break;

        case 'C' :
        displayText.setText("");
        numStr1 = "";
        numStr2 = "";
        firstInput = true;
        }
    }

    private String evaluate() {
        final char beep = '\u0007';

        try {
            int num1 = Integer.parseInt(numStr1);
            int num2 = Integer.parseInt(numStr2);
            int result = 0;

            switch (op) {
                case '+':
                result = num1 + num2;
                break;
                case '-':
                result = num1 - num2;
                break;
                case '*':
                result = num1 * num2;
                break;
                case '/':
                result = num1 + num2;
            }

            return String.valueOf(result);
        }
        catch (ArithmeticException e) {
            System.out.print(beep);
            return: "E R R O R: " + e.getMessage();
        }
        catch (NumberFormatException e) {
            System.out.print(beep);

            if (numStr1.equals(""))
            return "E R R O R : Invalid First Number";
            else
            return "E R R O R: Invalid Second Number";
        }
        catch (Exception e) {
            System.out.print(beep);
            return "E R R O R";
        }
    }//missing closing bracket for evaluate() method

    public static void main(String[] args) {
            Calculator C = new Calculator();
    }   
}//missing closing bracket for class

PS: In the future please code tags.

PS2: Looks like di2daer already gave you some pointers in regards of code that I wanted you to solve, well your life is little easier now...

locked_twilight 0 Newbie Poster · Answer 2 · 2009-10-11T20:29:19+00:00

When I thought about my program again, I got it fixed and my younger brother helped me(how embarrassing).

And yes, those errors are right:
The brackets, the String keys, and the WindowAdapter.
I just fixed it a minute ago.

The class, interface, enum error is because I placed some of my methods outside the class, which is illegal.

Thanks, di2daer and James. =)

And sorry for the wrong pasting of code.

locked_twilight 0 Newbie Poster · Answer 3 · 2009-10-11T20:32:29+00:00

Really sorry for the wrong post...
And I resolved it myself, thanks... Sorry to bother you Peter_budo.
I was just too overwhelmed(I have not coded for weeks).

And the replies here are a lot faster than I thought.
Really, really thanks to all of you guys again. :)

peter_budo 2,532 Code tags enforcer Team Colleague Featured Poster · Answer 4 · 2009-10-11T20:57:39+00:00

You been lucky as there seems to be few people around. During the work week it may take few hours.

locked_twilight 0 Newbie Poster · Answer 5 · 2009-10-11T21:48:50+00:00

Yeah, luckily it's Sunday.

I need to submit this tomorrow. O_o

Calculator Program - class, interface, or enum expected

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