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Java: switch and "illegal start of type"

5 replies on 1 page. Most recent reply: Sep 26, 2006 11:04 PM by Matthias Neumair

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Boston Thornton

Posts: 8
Nickname: preston
Registered: Sep, 2006

Java: switch and "illegal start of type" Posted: Sep 23, 2006 12:29 PM
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Greetings one and all:

I am modeling skeleton of a more complex education program I am writing for my son. I moved some code around and used a Java switch which is now producing errors such as illegal start of type.


import staugIO.StaugIO;
class MathMachine
{
private double Number1 = 0.0;
private double Number2 = 0.0;
private double total01 = 0.0;
private double total02 = 0.0;
private double total03 = 0.0;
private double total04 = 0.0;
private String MyOption;
private StaugIO io = new StaugIO();


public MathMachine()
{
}

public void setNumber1()
{
Number1 = io.readDouble("Enter the first number");
}

public void setNumber2()
{
Number2 = io.readDouble("Enter the second number");
}
public void setMathOption()
{
choice = io.readString("Enter choice 'Addition, Subtraction, Multiplication, Division' :");
}



switch(MyOption) //Problem is here
{
case 'Addition': total01 = Number1 + Number2;
io.writeInfo("The result for Additon is: " + total01);
break;

case 'Subtraction': if(Number1 > Number2)
{
total02 = Number1 - Number2;
io.writeInfo("The result for Subtraction is: " + total02);
break;
}
//
// else
// {
// total02 = Number2 - Number1;
// io.writeInfo("The result for Subtraction is: " + total02);
// break;
// }
//
// case 'Multiplication': total03 = Number1 * Number2;
// io.writeInfo("The result for Multiplication is: " + total03);
// break;
//
// case 'Division': if(Number2 = 0)
// {
// io.writeInfo("Can't divide Number1 by " + Number02);
// }
// else
// {
// Number1 / Number2;
// io.writeInfo("The results for Division is: " + total04);
// }
// if (Number1 = 0)
// {
// io.writeInfo("Can't divide Number1 by " + Number02);
// }
// else
/ {
// Number2 / Number1;
// io.writeInfo("The results for Division is: " + total04);
// }


}

}

public class MyMathAnswer
{

public static void main(String args[])
{
MathMachine MathNote = new MathMachine();
MathNote.setNumber1();
MathNote.setNumber2();
MathNote.AddIt();
MathNote.Subit();
MathNote.getAnswer();

System.exit(0);
}

}


Boston Thornton

Posts: 8
Nickname: preston
Registered: Sep, 2006

Re: Java: switch and "illegal start of type" Posted: Sep 23, 2006 2:05 PM
Reply to this message Reply
Okay, I got it. The number one rule is to not too many changes at once.

Here the answer:


import staugIO.StaugIO;
class MathMachine
{
private double Number1 = 0.0;
private double Number2 = 0.0;
private double total01 = 0.0;
private double total02 = 0.0;
private double total03 = 0.0;
private double total04 = 0.0;
private char MyOption = 'Q';
private String Menu;
private StaugIO io = new StaugIO();


public MathMachine()
{
}

public void setNumber1()
{
Number1 = io.readDouble("Enter the first number");
}

public void setNumber2()
{
Number2 = io.readDouble("Enter the second number");
}
public void setMenu()
{
io.readString("Enter choice 'A for Addition, M for Multiplication, Q for Quit' :");

}
public void setMathOption()
{




switch(MyOption)
{
case 'A': total01 = Number1 + Number2;
io.writeInfo("The result for Additon is: " + total01);
break;

case 'M': total02 = Number1 * Number2;
io.writeInfo("The result for Multiplication is: " + total02);
break;

case 'Q': io.writeInfo("Quit Program");
break;

default: io.writeInfo("\n\nThis is a invalid entry" + "\nPlease run the program again");

}
}
}

public class MathFactor1
{

public static void main(String args[])
{
MathMachine MathNote = new MathMachine();
MathNote.setNumber1();
MathNote.setNumber2();
MathNote.setMenu();
MathNote.setMathOption();


System.exit(0);
}

}

Vincent O'Sullivan

Posts: 724
Nickname: vincent
Registered: Nov, 2002

Re: Java: switch and "illegal start of type" Posted: Sep 23, 2006 3:16 PM
Reply to this message Reply
(Unlike Visual Basic) the select/case statement in Java only works with integers.

Boston Thornton

Posts: 8
Nickname: preston
Registered: Sep, 2006

Re: Java: switch and "illegal start of type" Posted: Sep 24, 2006 7:22 AM
Reply to this message Reply
> (Unlike Visual Basic) the select/case statement in Java
> only works with integers.

Thanks, I am still playing around with the concept.

lawrence deopante

Posts: 4
Nickname: enz
Registered: Sep, 2006

Re: Java: switch and "illegal start of type" Posted: Sep 26, 2006 5:25 PM
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ei.. you should declare a char. to have an expression in your swith selection or use java.io.* package and use Bufferedreader.

Matthias Neumair

Posts: 660
Nickname: neumi
Registered: Sep, 2003

Re: Java: switch and "illegal start of type" Posted: Sep 26, 2006 11:04 PM
Reply to this message Reply
Quote: "(Unlike Visual Basic) the select/case statement in Java only works with integers."

That's not complettely true.
It also works for "byte", characters and typesafe enumerations.
However, as far as I know, typesafe enumerations are the only Objects which can be used for the switch/case statement.

This example works perfectly.
    enum Correction {LEFT, RIGHT, CENTER};
    Correction dir = Correction.LEFT;
    switch (dir) {
        case LEFT:
            break;
        case RIGHT:
            break;
        case CENTER:
            break;
        default: //will never enter here, but it compiles. a null value throws a exception at the line "switch (dir) {"
            break;
    }


As for the other data types: Just use "if / else if / else" statements. "Switch / case" works almost the same way.

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