Problem with a program that is suppose to compute mas

[AZRebelCowgirl73]

I am new to Java and am currently taking a class where one of our assignments is to compute the mass of an aluminum block. We are currently on week 2 and only into our second chapter. I am completely lost! I have followed every example from the book I can find and I am getting errors all over the place. If anyone could help I would be extremely greatful! Thanks!

Here is what I have so far!

public class W3Ex33 {

//main(): application entry point
public static void main(String[] args) {
int density = 2.7;
int volume = length * Width * height;
int mass = density * volume;
int length
int width
int height

Scanner stdin = new Scanner(System.in); //set up input string

System.out.print("Length is: "); //read int length
double length = stdin.nextInt();

System.out.print("Width is: "); //read int width
double width = stdin.nextInt();

System.out.print("Height is: "); //read int height
doublt height = stdin.nextInt();

double volume = length * Width * height; //convert to metric equivalents

double mass = density * volume; //perform mass calculation

System.out.println("An aluminum block with:"); //display results
System.out.println(" length " + length);
System.out.println(" width " + width);
System.out.println(" height " + height);
System.out.println("has a Mass of " + mass);

} //End method main

} // end class W3Ex33



Once again, if anyone can help! Thanks so much!

[r035198x]

In the code below

 
int volume = length * Width * height;
int mass = density * volume;
int length
int width
int height
 

You use length, Width and height before defining them. When you do define them, the statements are missing the ; at the end. Go through the rest of your code and check for any similar mistakes.

[JosAH]

@OP: did you read what the compiler was trying to tell you? Compiler diagnostics
are extremey useful if you know how to read them. From a quick scan:

1) width and Width are two separate words/identifiers;
2) no semicolons after the definition of a few variables;
3) use before set errors for a few variables;
4) scanning ints and assigning them to doubles.

First follow up the advice the compiler tried to give to you.

kind regards,

Jos

[AZRebelCowgirl73]

Here are all the corrections I could personally find and the results left over:
I still get 7 errors:

public class W3Ex33 {

//main(): application entry point
public static void main(String[] args) {
double length;
double width;
double height;
double density = 2.7;
double volume = length * width * height;
double mass = density * volume;


Scanner stdin = new Scanner(System.in); //set up input string

System.out.print("Length is: "); //read int length
double length = stdin.nextInt();

System.out.print("Width is: "); //read int width
double width = stdin.nextInt();

System.out.print("Height is: "); //read int height
double height = stdin.nextInt();

double volume = length * width * height; //convert to metric equivalents

double mass = density * volume; //perform mass calculation

System.out.println("An aluminum block with:"); //display results
System.out.println(" length " + length);
System.out.println(" width " + width);
System.out.println(" height " + height);
System.out.println("has a Mass of " + mass);

} //End method main

} // end class W3Ex33





The Errors I get are as follows:

From the Command Prompt Window:

C:\W3Ex33>javac W3Ex33.java
W3Ex33.java:31: cannot find symbol
symbol : class Scanner ( I get this error message twice for line to set up input strings.

then for each input I am getting a length width height volume and mass are already defined in main(java.lang.String[])

Thanks For the HELP!

ALI

[Ganon11]

When you are reading into the variables, you say something like

double length = stdin.nextInt();

which is trying to declare a new variable called length. You should say

length = stdin.nextInt();

to assign a value to the alread-assigned variabled named length. You do the same thing when initializing volume and mass.

Alternatively, you can get rid of the variable declarations at the beginning of main() except for density.

[AZRebelCowgirl73]

public class W3Ex33 {

//main(): application entry point
public static void main(String[] args) {
double length;
double width;
double height;
double density = 2.7;
double volume = length * width * height;
double mass = density * volume;


Scanner stdin = new Scanner(System.in); //set up input string

System.out.print("Length is: "); //read int length
length = stdin.nextInt();

System.out.print("Width is: "); //read int width
width = stdin.nextInt();

System.out.print("Height is: "); //read int height
height = stdin.nextInt();

volume = length * width * height; //convert to metric equivalents

mass = density * volume; //perform mass calculation

System.out.println("An aluminum block with:"); //display results
System.out.println(" length " + length);
System.out.println(" width " + width);
System.out.println(" height " + height);
System.out.println("has a Mass of " + mass);

} //End method main

} // end class W3Ex33





The Errors I get are as follows: 2 errors left!

From the Command Prompt Window:

C:\W3Ex33>javac W3Ex33.java
W3Ex33.java:31: cannot find symbol
symbol : class Scanner ( I get this error message twice for line to set up input strings.
They are in reference to the word Scanner twice on that line!

Thanks again! ALI

[JosAH]

W3Ex33.java:31: cannot find symbol
symbol : class Scanner ( I get this error message twice for line to set up input strings.
They are in reference to the word Scanner twice on that line!

Thanks again! ALI

The Scanner class is defined in the "java.util" package so you should import it.
Only the classes defined in "java.lang" don't need an explicit import statement.

At the top of your source file you should add a line:

import java.util.Scanner;

... see what happens then.

kind regards,

Jos

[AZRebelCowgirl73]

I guess when they mean trial and error, atleast in my case they definately mean the error part. now I am getting a completely new message:

Here is my code:

import java.util.Scanner;
public class W3Ex33 {

//main(): application entry point
public static void main(String[] args) {
double length;
double width;
double height;
double density = 2.7;
double volume = length * width * height;
double mass = density * volume;


Scanner stdin = new Scanner(System.in); //set up input string

System.out.print("Length is: "); //read int length
length = stdin.nextInt();

System.out.print("Width is: "); //read int width
width = stdin.nextInt();

System.out.print("Height is: "); //read int height
height = stdin.nextInt();

volume = length * width * height; //convert to metric equivalents

mass = density * volume; //perform mass calculation

System.out.println("An aluminum block with:"); //display results
System.out.println(" length " + length);
System.out.println(" width " + width);
System.out.println(" height " + height);
System.out.println("has a Mass of " + mass);

} //End method main

} // end class W3Ex33



Here is the error message I am getting:

I get it in three places on the same line:

W3Ex33.java:27: variable length might not have been initialized;
double volume = length * width * height;

W3Ex33.java:27: variable width might not have been initialized;
double volume = length * width * height;

W3Ex33.java:27: variable height might not have been initialized;
double volume = length * width * height;

Thanks Again! ALI

[JosAH]

IHere is the error message I am getting:

I get it in three places on the same line:

W3Ex33.java:27: variable length might not have been initialized;
double volume = length * width * height;

W3Ex33.java:27: variable width might not have been initialized;
double volume = length * width * height;

W3Ex33.java:27: variable height might not have been initialized;
double volume = length * width * height;

Thanks Again! ALI

Yup, that's what you get if you're trying to use variables before they've got a
sensible value. Don't try to multiply those three variables until after they've
received a sensible value, i.e. after you've scanned the values for them

kind regards,

Jos

[AZRebelCowgirl73]

Yup, that's what you get if you're trying to use variables before they've got a
sensible value. Don't try to multiply those three variables until after they've
received a sensible value, i.e. after you've scanned the values for them

kind regards,

Jos

Well what you just wrote was like korean to me! However, i think I have figured it out, you are a genius and a saint, and I thank you from the bottom of my frazzled heart. I just hope I can get things alittle easier as the semester progresses and once again! Thanks A Million!

ALI :P

[JosAH]

Well what you just wrote was like korean to me! However, i think I have figured it out, you are a genius and a saint, and I thank you from the bottom of my frazzled heart. I just hope I can get things alittle easier as the semester progresses and once again! Thanks A Million!

ALI :P

It's not as complicated as it seems; this was your code:

double length;
double width;
double height;
double volume= length*width*heigth;

Local variables don't have a value before you explicitly give them one, either
by initialization or by assignment. The top three local variables don't have a
value. Then all of a sudden you want to initialize variable 'volume' with the
value of the product of the other three variables. What's their value then?

The compiler is smart enough to notice that and starts to complain about it.
You don't know their values either because the user hasn't supplied values
for them yet. That only happens later in your program when you use your
Scanner object. Only then, after all three variables have a value assigned
you can calculate your formula length*width*height. Programming is not
about voodoo and psychic events you know, computers are as stupid as they
can be.

kind regards,

Jos

[Ganon11]

...computers are as stupid as they can be.

In fact, they are so stupid, they can only do what we tell them to do.

[r035198x]

... you are a genius and a saint...

Jos? Genius and saint?

Wait 'till he puts his nitpicking armour on.

[JosAH]

Jos? Genius and saint?

Wait 'till he puts his nitpicking armour on.

Small correction: my shiny nitpicking armour ;-)

kind regards,

Jos

[r035198x]

Small correction: my shiny nitpicking armour ;-)

kind regards,

Jos

Exactly what I was talking about.