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.

Edited 3 Years Ago by Dani: Formatting fixed

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

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...

Edited 3 Years Ago by happygeek: fixed formatting

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.

Edited 7 Years Ago by locked_twilight: n/a

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. :)

Edited 3 Years Ago by happygeek: fixed formatting

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