Question

I am to stimulate a java applet of a menu with checkboxes and checkboxgroups, with calories listed next to each food choice. My problem is I cannot figure out why I keep getting this error message when i compile it:

AnAppletWithCheckboxes.java:188: illegal forward reference
int crepeVal = Integer.parseInt(textField.getText());

I get that for every line that I have is converting the textField into an int, so hence there are 17 errors. Any idea of why will be appreciated!

Here is my Code:: it is very long because there are plenty checkboxes and textFields. I commented Out My place of Error! :

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class AnAppletWithCheckboxes extends Applet implements ItemListener {
    public void init() {
        setLayout(new GridLayout(1, 0));

    CheckboxGroup dinnerType = new CheckboxGroup();
    standard = new Checkbox("standard", dinnerType, false);
    standard.addItemListener(this);
    deluxe = new Checkbox("deluxe", dinnerType, true);
    deluxe.addItemListener(this);   

    CheckboxGroup appetizers = new CheckboxGroup();
    crepe = new Checkbox("crepe", appetizers, false);
    crepe.addItemListener(this);
    quiche = new Checkbox("quiche", appetizers, false);
    quiche.addItemListener(this);
    dumpling = new Checkbox("dumpling", appetizers, false);
    dumpling.addItemListener(this);

textField = new TextField("300");
    textField.setEditable(false);
textField2 = new TextField("330");
    textField2.setEditable(false);
textField3 = new TextField("98");
    textField3.setEditable(false);

    CheckboxGroup soupOrSalad = new CheckboxGroup();

    soup = new Checkbox("Soup", soupOrSalad, false);
    soup.addItemListener(this);

    CheckboxGroup soups = new CheckboxGroup();
    cream = new Checkbox("cream", soups, false);
    cream.addItemListener(this);
    broth = new Checkbox("broth", soups, false);
    broth.addItemListener(this);
    gumbo = new Checkbox("gumbo", soups, false);
    gumbo.addItemListener(this);

textField4 = new TextField("190");
    textField4.setEditable(false);
textField5 = new TextField("20");
    textField5.setEditable(false);
textField6 = new TextField("110");
    textField6.setEditable(false);

    salad = new Checkbox("Salad", soupOrSalad, false);
    salad.addItemListener(this);

    CheckboxGroup salads = new CheckboxGroup();
    tossed = new Checkbox("tossed", salads, false);
    tossed.addItemListener(this);
    caesar = new Checkbox("caesar", salads, false);
    caesar.addItemListener(this);
    croutons = new Checkbox("croutons");
    croutons.addItemListener(this);
    lite = new Checkbox("lite dressing");
    lite.addItemListener(this);

textField7 = new TextField("35");
    textField7.setEditable(false);
textField8 = new TextField("90");
    textField8.setEditable(false);
textField9 = new TextField("60");
    textField9.setEditable(false);
textField10 = new TextField("50");
    textField10.setEditable(false);

    CheckboxGroup entrees = new CheckboxGroup();
    chicken = new Checkbox("chicken", entrees, false);
    chicken.addItemListener(this);
    beef = new Checkbox("beef", entrees, false);
    beef.addItemListener(this);
    lamb = new Checkbox("lamb", entrees, false);
    lamb.addItemListener(this);
    fish = new Checkbox("fish", entrees, false);
    fish.addItemListener(this);

textField11 = new TextField("200");
    textField11.setEditable(false);
textField12 = new TextField("170");
    textField12.setEditable(false);
textField13 = new TextField("65");
    textField13.setEditable(false);
textField14 = new TextField("150");
    textField14.setEditable(false);

    CheckboxGroup deserts = new CheckboxGroup();
    pie = new Checkbox("pie", deserts, false);
    pie.addItemListener(this);
    fruit = new Checkbox("fruit", deserts, false);
    fruit.addItemListener(this);
    sherbet = new Checkbox("sherbet", deserts, false);
    sherbet.addItemListener(this);

textField15 = new TextField("80");
    textField15.setEditable(false);
textField16 = new TextField("60");
    textField16.setEditable(false);
textField17 = new TextField("107");
    textField17.setEditable(false);

calories = new Button("Calories");

calTextField = new TextField("0"+total);
    calTextField.setEditable(false);

    setLayout(new GridLayout(0, 1));

    Panel p = new Panel();
    add(p);
    p.add(standard);
    p.add(deluxe);

    appetizerPanel = new Panel();
    add(appetizerPanel);
label = new Label("Appetizer");
    appetizerPanel.add(label);
    appetizerPanel.add(crepe);
appetizerPanel.add(textField);
    appetizerPanel.add(quiche);
appetizerPanel.add(textField2);
    appetizerPanel.add(dumpling);
appetizerPanel.add(textField3);

    soupPanel = new Panel();
    add(soupPanel);
    soupPanel.add(soup);
    soupPanel.add(cream);
soupPanel.add(textField4);
    soupPanel.add(broth);
soupPanel.add(textField5);
    soupPanel.add(gumbo);
soupPanel.add(textField6);

    saladPanel = new Panel();
    add(saladPanel);
    saladPanel.add(salad);
    saladPanel.add(tossed);
saladPanel.add(textField7);
    saladPanel.add(caesar);
saladPanel.add(textField8);
    saladPanel.add(croutons);
saladPanel.add(textField9);
    saladPanel.add(lite);
saladPanel.add(textField10);

    entreePanel = new Panel();
    add(entreePanel);
label2 = new Label("Entree");
    entreePanel.add(label2);
    entreePanel.add(chicken);
entreePanel.add(textField11);
    entreePanel.add(beef);
entreePanel.add(textField12);
    entreePanel.add(lamb);
entreePanel.add(textField13);
    entreePanel.add(fish);
entreePanel.add(textField14);

desertPanel = new Panel();
    add(desertPanel);
label3 = new Label("Desert");
    desertPanel.add(label3);
    desertPanel.add(pie);
desertPanel.add(textField15);
    desertPanel.add(fruit);
desertPanel.add(textField16);
    desertPanel.add(sherbet);
desertPanel.add(textField17);

caloriesPanel = new Panel();
add(caloriesPanel);
caloriesPanel.add(calories);
caloriesPanel.add(calTextField);
}    

public void LabelChange(Label b) { 
if (b ==label3)
    b.setForeground(Color.lightGray);
else
    label3.setForeground(Color.black);
}

/* This is where i get those errors!! */

int crepeVal = Integer.parseInt(textField.getText());
int quicheVal = Integer.parseInt(textField2.getText());
int dumplingVal = Integer.parseInt(textField3.getText());
int creamVal = Integer.parseInt(textField4.getText());
int brothVal = Integer.parseInt(textField5.getText());
int gumboVal = Integer.parseInt(textField6.getText());
int tossedVal = Integer.parseInt(textField7.getText());
int caesarVal = Integer.parseInt(textField8.getText());
int croutonsVal = Integer.parseInt(textField9.getText());
int liteVal = Integer.parseInt(textField10.getText());
int chickenVal = Integer.parseInt(textField11.getText());
int beefVal = Integer.parseInt(textField12.getText());
int lambVal = Integer.parseInt(textField13.getText());
int fishVal = Integer.parseInt(textField14.getText());
int pieVal = Integer.parseInt(textField15.getText());
int fruitVal = Integer.parseInt(textField16.getText());
int sherbetVal = Integer.parseInt(textField17.getText());

public boolean action(Event evt, Object whatAction){
if(!(evt.target instanceof Button)){
    return false;
} 
else {
    calorieCount();
    return true;
}    
}

public void calorieCount () {
if (crepe.getState()) 
    crepeVal += total;
else
    crepeVal = 0;
if (quiche.getState()) 
    quicheVal += total;
else
    quicheVal = 0;
if (dumpling.getState()) 
    dumplingVal += total;
else
    dumplingVal= 0;
if (cream.getState()) 
    creamVal += total;
else
    creamVal = 0;
if (broth.getState()) 
    brothVal += total;
else
    brothVal = 0;
if (gumbo.getState()) 
    gumboVal += total;
else
    gumboVal = 0;
if (tossed.getState()) 
    tossedVal += total;
else
    tossedVal = 0;
if (caesar.getState()) 
    caesarVal += total;
else
    caesarVal = 0;
if (croutons.getState()) 
    croutonsVal += total;
else
    croutonsVal = 0;
if (lite.getState()) 
    liteVal += total;
else
    liteVal = 0;
if (chicken.getState()) 
    chickenVal += total;
else
    chickenVal = 0;
if (beef.getState()) 
    beefVal += total;
else
    beefVal = 0;
if (lamb.getState()) 
    lambVal += total;
else
    lambVal = 0;
if (fish.getState()) 
    fishVal += total;
else
    fishVal = 0;
if (pie.getState()) 
    pieVal += total;
else
    pieVal = 0;
if (fruit.getState()) 
    fruitVal += total;
else
    fruitVal = 0;
if (sherbet.getState()) 
    sherbetVal += total;
else
    sherbetVal = 0;  
}

public void itemStateChanged(ItemEvent e) {
    if (e.getSource() == standard || e.getSource() == deluxe)
        handleDinnerType((Checkbox)e.getSource());
    else if (e.getSource() == soup || e.getSource() == salad)
        handleSoupSaladChoice((Checkbox)e.getSource());
}

void handleDinnerType(Checkbox selectedType) {
    boolean enabled;
    if (selectedType == standard){
        enabled = false;
    LabelChange(label3);
}
    else{
        enabled = true;
    LabelChange(label);
}

soup.setEnabled(enabled);
salad.setEnabled(enabled);
    pie.setEnabled(enabled);
    fruit.setEnabled(enabled);
    sherbet.setEnabled(enabled);
    cream.setEnabled(enabled);
    broth.setEnabled(enabled);
    gumbo.setEnabled(enabled);
    tossed.setEnabled(enabled);
    caesar.setEnabled(enabled);
    croutons.setEnabled(enabled);
    lite.setEnabled(enabled);

}

void handleSoupSaladChoice(Checkbox selectedCourse) {
    boolean soupEnabled, saladEnabled;
    if (selectedCourse == soup) {
        soupEnabled = true;
        saladEnabled = false;
    soup.setForeground(Color.BLACK);
        salad.setForeground(Color.lightGray);
    }
    else {
        soupEnabled = false;
        saladEnabled = true;
    soup.setForeground(Color.lightGray);
        salad.setForeground(Color.BLACK);
    }
    cream.setEnabled(soupEnabled);
    broth.setEnabled(soupEnabled);
    gumbo.setEnabled(soupEnabled);

    tossed.setEnabled(saladEnabled);
    caesar.setEnabled(saladEnabled);
    croutons.setEnabled(saladEnabled);
    lite.setEnabled(saladEnabled);
}

Label
label, label2, label3;

Panel
    appetizerPanel, soupPanel, saladPanel, entreePanel, desertPanel, caloriesPanel;

Checkbox
    standard, deluxe,
    soup, salad,
    crepe, quiche, dumpling,
    cream, broth, gumbo,
    tossed, caesar,
    croutons, lite,
    chicken, beef, lamb, fish,
    pie, fruit, sherbet;

Button calories;
int total = 0;

TextField
textField, textField2, textField3,
textField4, textField5, textField6,
textField7, textField8, textField9,
textField10, textField11, textField12, 
textField13, textField14, textField15, 
textField16, textField17, calTextField;

}

Answer 1

In Java, you are not allowed to refer to a field a in an initializer of another field b if b is declared before a in the source code. That is, this is allowed:

int b = 3;
int a = b;

but this is not allowed:

int a = b;
int b = 3;

By the way, if Java had some magic way of figuring out that textField had to be initialized before crepeVal, you would still get a NullPointerException since textField is null after object construction.