help

[Jade Davidson]

I must be overlooking something obvious, but I don't know why I am getting "else without if" compiler errors.

<font size=2.5>
import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
public class CalcApplet extends Applet
              implements MouseListener {
   boolean first_num_flag == true;
   String display = "0";
   int num1, num2 = 0;
   char Op;
   int result = 0;
//Declare the text field to be used for input and output:
   private TextField textInput = new TextField("");
//Declare the buttons of the calculator:
   private Button btn1 = new Button("1");
   private Button btn2 = new Button("2");
   private Button btn3 = new Button("3");
   private Button btnDiv = new Button("/");
   private Button btn4 = new Button("4");
   private Button btn5 = new Button("5");
   private Button btn6 = new Button("6");
   private Button btnMult = new Button("*");
   private Button btn7 = new Button("7");
   private Button btn8 = new Button("8");
   private Button btn9 = new Button("9");
   private Button btnSub = new Button("-");
   private Button btn0 = new Button("0");
   private Button btnClear = new Button("C");
   private Button btnEqual = new Button("=");
   private Button btnAdd = new Button("+");
   private String sSavedValue;
   private char charPreviousCalc;

   public void init() {
//Declare a panel to group all the calculator buttons together:
      Panel calcPanel = new Panel();
      calcPanel.setLayout(new GridLayout(4,4));
      calcPanel.add(btn1);
      calcPanel.add(btn2);
      calcPanel.add(btn3);
      calcPanel.add(btnDiv);
      calcPanel.add(btn4);
      calcPanel.add(btn5);
      calcPanel.add(btn6);
      calcPanel.add(btnMult);
      calcPanel.add(btn7);
      calcPanel.add(btn8);
      calcPanel.add(btn9);
      calcPanel.add(btnSub);
      calcPanel.add(btn0);
      calcPanel.add(btnClear);
      calcPanel.add(btnEqual);
      calcPanel.add(btnAdd);
      btn1.addMouseListener(this);
      btn2.addMouseListener(this);
      btn3.addMouseListener(this);
      btnDiv.addMouseListener(this);
      btn4.addMouseListener(this);
      btn5.addMouseListener(this);
      btn6.addMouseListener(this);
      btnMult.addMouseListener(this);
      btn7.addMouseListener(this);
      btn8.addMouseListener(this);
      btn9.addMouseListener(this);
      btnSub.addMouseListener(this);
      btn0.addMouseListener(this);
      btnClear.addMouseListener(this);
      btnEqual.addMouseListener(this);
      btnAdd.addMouseListener(this);
//Add the panel & text field to the applet in a border layout:
      setLayout(new BorderLayout());
      add(textInput,BorderLayout.NORTH);
      add(calcPanel,BorderLayout.CENTER);
  }
   public void mousePressed(MouseEvent event) {
      Object source = event.getSource();
   
      if (source == btn0)
         if (first_num_flag == true)
            display = "0";
            first_num_flag = false;
         else
            display += "0";
      textInput.setText(display);
      
      if (source == btn1)
         if (first_num_flag == true)
            display = "1";
            first_num_flag = false;
         else
            display += "1";
      textInput.setText(display);
      
      if (source == btn2)
         if (first_num_flag == true)
            display = "2";
            first_num_flag = false;
         else
            display += "2";
      textInput.setText(display);
      if (source == btn3)
         if (first_num_flag == true)
            display = "3";
            first_num_flag = false;
         else
            display += "3";
      textInput.setText(display);
      if (source == btn4)
         if (first_num_flag == true)
            display = "4";
            first_num_flag = false;
         else
           display += "4";
      textInput.setText(display);
      if (source == btn5)
         if (first_num_flag == true)
            display = "5";
            first_num_flag = false;
         else
            display += "5";
      textInput.setText(display);
      if (source == btn6)
         if (first_num_flag == true)
            display = "6";
            first_num_flag = false;
         else
            display += "6";
      textInput.setText(display);
      if (source == btn7)
         if (first_num_flag == true)
            display = "7";
            first_num_flag = false;
         else
            display += "7";
      textInput.setText(display);
      if (source == btn8)
         if (first_num_flag == true)
            display = "8";
            first_num_flag = false;
         else
            display += "8";
      textInput.setText(display);
      if (source == btn9)
         if (first_num_flag == true)
            display = "9";
            first_num_flag = false;
         else
            display += "9";
      textInput.setText(display);
      else
      if (source == btnAdd) {
         first_num_flag = true;
         num1 = Integer.parseInt(display);
         Op = '+';
      }
      else
      if (source == btnSub) {
         first_num_flag = true;
         num1 = Integer.parseInt(display);
         Op = '-';
      }
      else
      if (source == btnMult) {
         first_num_flag = true;
         num1 = Integer.parseInt(display);
         Op = '*';
      }
      else 
      if (source == btnDiv) {
         first_num_flag = true;
         num1 = Integer.parseInt(display);
         Op = '/';
      }
      else 
      if (source == btnEqual) {
         num2 = Integer.parseInt(display);
         
         switch(Op) 
         {
            case '+':
               result = num1 + num2;
               break;
            case '-':
               result = num1 - num2;
               break;
            case '*':
               result = num1 * num2;
               break;
            case '/':
               result = num1 / num2;
         }
   
         num2 = result;
         first_num_flag = true;
     }
   }
   public void mouseClicked(MouseEvent event) {
   }
   public void mouseReleased(MouseEvent event) {
   }
   public void mouseEntered(MouseEvent event) {
   }
   public void mouseExited(MouseEvent event) {
   }
}
 

(edited by Cindy to format code)
[This message has been edited by Cindy Glass (edited December 14, 2001).]

[David O'Meara]

Ack!
Go to the effort of including brackets even for single line statements, you'll save on so much stress in the long run.
Bit hard to see your layout since you didn't use the UBB [ code] tags, but I recommend lining up the start and end braces.

    public void myMethod() throws Exception
    {
        if(statement)
        {
            System.out.println("I'm here, no confusion");
        }
        else
        {
            throw new Exception("Everything is fine, thanks.");
        }
    }

Dave.

[William Barnes]

First problem:

 boolean first_num_flag == true;

Second problem:

if (source == btn0)
  if (first_num_flag == true)
    display = "0";
    first_num_flag = false;
  else

If you wrote this with 1] an editor that indented automatically, or 2] used {} correctly you would see the problem

if (source == btn0)
{
  if (first_num_flag == true)
  {
    display = "0";
  }
  first_num_flag = false; // <--------------------------***
  else

[Jade Davidson]

OK, I see it now. thanks.