It doesnt see my 'if' statements

[W. Schaible]

A stripped down version of my program is in the 2 files copied below. It is a simple calculator like in Windows accessories. The example below only does addition and subtraction however it doesn't work. Here's how it is supposed to work. A number is sent to the textbox using button clicks and when '+' button is clicked the displayed string is converted to double. The displayed string remains displayed until the first digit of the next number is entered then the first number is cleared and the second number begins in the display. When '=' is clicked the second displayed number (actually a string) is converted to double and added to the first double number. The operation should be controlled by the 'opFlag' and 'addFlag' settings. The problem apparently is that the 'if' statements that set the flags are not being executed. I tried NetBeans debugger to watch the values but I don't know how to use the debugger well enough. I'm hoping someone here can tell me what I'm doing wrong so I can move on. Your comments will be appreciated. TIA Bill S.

THE GUI FILE:

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

public class CalcGUIQ2 extends JFrame {
CrunchQ2 crunchNu = new CrunchQ2(this);

    // set up row 1
   JPanel row1 = new JPanel();
   JTextField number1 = new JTextField(30);
    // set up row 2
   JPanel row2 = new JPanel();



   JButton sev = new JButton("7");
   JButton ate = new JButton("8");
   JButton nin = new JButton("9");

   JButton fou = new JButton("4");
   JButton fiv = new JButton("5");
   JButton six = new JButton("6");

   JButton one = new JButton("1");
   JButton two = new JButton("2");
   JButton tre = new JButton("3");
   JButton add = new JButton("+");
   JButton sub = new JButton("--");


   JButton zro = new JButton("0");
   JButton dot = new JButton(".");
   JButton equ = new JButton("=");

    public CalcGUIQ2() {
        super();
        setTitle("Calculator");


        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        GridLayout layout = new GridLayout(2, 1, 10, 10);
        setLayout(layout);

        //add listeners
        dot.addActionListener(crunchNu);
        zro.addActionListener(crunchNu);
        one.addActionListener(crunchNu);
        two.addActionListener(crunchNu);
        tre.addActionListener(crunchNu);
        fou.addActionListener(crunchNu);
        fiv.addActionListener(crunchNu);
        six.addActionListener(crunchNu);
        sev.addActionListener(crunchNu);
        ate.addActionListener(crunchNu);
        nin.addActionListener(crunchNu);
        equ.addActionListener(crunchNu);

        add.addActionListener(crunchNu);
        sub.addActionListener(crunchNu);

        FlowLayout layout1 = new FlowLayout(FlowLayout.CENTER, 10, 10);
        row1.add(number1);
        row1.setLayout(layout1);
        add(row1);

        GridLayout layout2 = new GridLayout(5, 3, 10, 10);
        row2.setLayout(layout2);

   row2.add (sev);
   row2.add (ate);
   row2.add (nin);

   row2.add (fou);
   row2.add (fiv);
   row2.add (six);

   row2.add (one);
   row2.add (two);
   row2.add (tre);

   row2.add (zro);
   row2.add (dot);
   row2.add (equ);
   row2.add (add);
   row2.add (sub);

   add(row2);


        pack();
        setVisible(true);
    }


    public static void main(String[] arguments) {
        CalcGUIQ2 frame = new CalcGUIQ2();

    }
}

THE CALCULATION FILE:

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

public class CrunchQ2 implements ActionListener{
    CalcGUIQ2 gui;
    String strng1 = "";
    String noChar = "";
    String nine = "999999999";
    boolean addFlag = false;
    boolean subFlag = false;
    boolean opFlag = false;

    Double operand1 = 0.0;
    Double operand2 = 0.0;
    public CrunchQ2(CalcGUIQ2 in) {
    gui = in;
      }
public void actionPerformed(ActionEvent event){
     String btn = event.getActionCommand();
           // opflag clears display
           if (opFlag){
               gui.number1.setText(noChar);
               opFlag = false;
            }
           if (btn == "=") {
                operand2=Double.parseDouble(strng1);

                if (addFlag) {
                operand1 += operand2;
                addFlag = false;
            }
                if (subFlag) {
                operand1 -= operand2;
                subFlag = false;
            }
           }
           if (btn == ".") {strng1 += btn;}
      else if (btn == "0") {strng1 += btn;}
      else if (btn == "1") {strng1 += btn;}
      else if (btn == "2") {strng1 += btn;}
      else if (btn == "3") {strng1 += btn;}
      else if (btn == "4") {strng1 += btn;}
      else if (btn == "5") {strng1 += btn;}
      else if (btn == "6") {strng1 += btn;}
      else if (btn == "7") {strng1 += btn;}
      else if (btn == "8") {strng1 += btn;}
      else if (btn == "9") {strng1 += btn;}
      gui.number1.setText(strng1);


           if (btn == "+") {
               addFlag = true;
               opFlag = true;
               operand1=Double.parseDouble(strng1);}

           if (btn == "--") {
               subFlag = true;
               opFlag = true;
               operand1=Double.parseDouble(strng1);}

[Added code tags - see UseCodeTags]

[Michael Dunn]

if (btn == "+")

try it like this

if (btn.equals("+"))

same for the other one

[Sumit Patil]

I tried NetBeans debugger to watch the values but I don't know how to use the debugger well enough.

You can always use System.out.println() to see the values...

[fred rosenberger]

W. Schaible,

I copied part of your code, and re-posted it here using "code tags". as you can see, it is formatted much better, is context-highlighted, and is much more readable. Please start using these in the future. You can simply highlight your source and click the button labeled "code" above where you enter your text.

Thanks.

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

public class CalcGUIQ2 extends JFrame {
CrunchQ2 crunchNu = new CrunchQ2(this);

    // set up row 1
   JPanel row1 = new JPanel();
   JTextField number1 = new JTextField(30);
    // set up row 2
   JPanel row2 = new JPanel();



   JButton sev = new JButton("7");
   JButton ate = new JButton("8");
   JButton nin = new JButton("9");

   JButton fou = new JButton("4");
   JButton fiv = new JButton("5");
   JButton six = new JButton("6");

   JButton one = new JButton("1");
   JButton two = new JButton("2");
   JButton tre = new JButton("3");
   JButton add = new JButton("+");
   JButton sub = new JButton("--");


   JButton zro = new JButton("0");
   JButton dot = new JButton(".");
   JButton equ = new JButton("=");

    public CalcGUIQ2() {
        super();
        setTitle("Calculator");


        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        GridLayout layout = new GridLayout(2, 1, 10, 10);
        setLayout(layout);

        //add listeners
        dot.addActionListener(crunchNu);
        zro.addActionListener(crunchNu);
        one.addActionListener(crunchNu);
        two.addActionListener(crunchNu);
        tre.addActionListener(crunchNu);
        fou.addActionListener(crunchNu);
        fiv.addActionListener(crunchNu);
        six.addActionListener(crunchNu);
        sev.addActionListener(crunchNu);
        ate.addActionListener(crunchNu);
        nin.addActionListener(crunchNu);
        equ.addActionListener(crunchNu);

        add.addActionListener(crunchNu);
        sub.addActionListener(crunchNu);

        FlowLayout layout1 = new FlowLayout(FlowLayout.CENTER, 10, 10);
        row1.add(number1);
        row1.setLayout(layout1);
        add(row1);

        GridLayout layout2 = new GridLayout(5, 3, 10, 10);
        row2.setLayout(layout2);

   row2.add (sev);
   row2.add (ate);
   row2.add (nin);

   row2.add (fou);
   row2.add (fiv);
   row2.add (six);

   row2.add (one);
   row2.add (two);
   row2.add (tre);

   row2.add (zro);
   row2.add (dot);
   row2.add (equ);
   row2.add (add);
   row2.add (sub);

   add(row2);


        pack();
        setVisible(true);
    }


    public static void main(String[] arguments) {
        CalcGUIQ2 frame = new CalcGUIQ2();

    }
}

[W. Schaible]

this is a test. Your method removed indentation and removed context highlighting. Your method does the opposite of what you say.

[code=java]import javax.swing.*;import java.awt.*;

public class SalutonFrame2 extends JFrame {
    public SalutonFrame2() {
        super("SalutonFrame2");
        setLookAndFeel();
        setSize(350, 100);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        JLabel salutonLabel = new JLabel("Saluton mondo!");
        FlowLayout flo = new FlowLayout();
        setLayout(flo);
        add(salutonLabel);
        setVisible(true);
    }

    private void setLookAndFeel() {
        try {
            UIManager.setLookAndFeel(
                "com.sun.java.swing.plaf.nimbus.NimbusLookAndFeel"
            );
        } catch (Exception exc) {
            // ignore error
        }
    }
    
    public static void main(String[] arguments) {
        SalutonFrame2 sal = new SalutonFrame2();

}[/code][/code][/code]