compiling a java program

[swappo1]

Hello,

I am taking a class in programming in a month and they will be teaching java. I thought I would start early and familiarize myself with java using a library copy of Sams teach yourself java6 in 21 days. I was able to get a simple hello world program with one file to compile and run. When I try to get a program with two files to compile I get some errors. Here is the errors and files:


VolcanoRobot.java
class VolcanoRobot
{
String status; //instance variables
int speed
float temperature;

void checkTemperature() //method
{
if(temperature > 660)
{
status = "returning home";
speed = 5;
}
}

void showAttributes()
{
System.out.println("Status: " + status);
System.out.println("Speed: " + speed);
System.out.println("Temerature: " + temperature);
}
}

VolcanoApplication.java
class VolcanoApplication
{
public static void main(String[] arguments)
{
VolcanoRobot dante = new VolcanoRobot();
dante.status = "exploring";
dante.speed = 2;
dante.temperature = 510;

dante.showAttributes();
System.out.println("Increasing speed to 3.");
dante.speed = 3;
dante.showAttributes();
System.out.println("Changing temperature to 670.");
dante.temperaure = 670;
dante.showAttributes();
System.out.println("Checking the temperature.");
dante.checkTemperature();
dante.showAttributes();
}
}

Errors:
[hopchewer@hopchewer volcanorobot]$ javac VolcanoApplication.java
----------
1. ERROR in VolcanoApplication.java (at line 25)
VolcanoRobot dante = new VolcanoRobot();
^^^^^^^^^^^^
VolcanoRobot cannot be resolved to a type
----------
2. ERROR in VolcanoApplication.java (at line 25)
VolcanoRobot dante = new VolcanoRobot();
^^^^^^^^^^^^
VolcanoRobot cannot be resolved to a type
----------
2 problems (2 errors)[hopchewer@hopchewer volcanorobot]$
I am using gedit along with the terminal plugin. The two files are saved in volcanorobot. Any ideas what I am doing wrong?

[baizon]

First you have to compile VolcanoRobot.java, then VolcanoApplication.java. The error is because the main method is trying to access the VolcanoRobot.class but could not find it.



hopchewer@hopchewer volcanorobot]$ javac VolcanoRobot.java
hopchewer@hopchewer volcanorobot]$ javac VolcanoApplication.java


P.S.
You got 2 syntax errors in the code.


VolcanoApplication.java
dante.temperature = 670;

VolcanoRobot.java
int speed;

[swappo1]

Ok, I fixed my two syntax errors. I compiled VolcanoRobot.java and now have VolcanoRobot.class in the volcanorobot folder. When I compile VolcanoApplication, I get the same errors again.

[hopchewer@hopchewer volcanorobot]$ javac VolcanoApplication.java
----------
1. ERROR in VolcanoApplication.java (at line 5)
VolcanoRobot dante = new VolcanoRobot();
^^^^^^^^^^^^
VolcanoRobot cannot be resolved to a type
----------
2. ERROR in VolcanoApplication.java (at line 5)
VolcanoRobot dante = new VolcanoRobot();
^^^^^^^^^^^^
VolcanoRobot cannot be resolved to a type
----------
2 problems (2 errors)[hopchewer@hopchewer volcanorobot]$

[baizon]

Ah ok, i think i found whats wrong.
Please change class to "public class".


public class VolcanoRobot {
String status; //instance variables
int speed;
float temperature;

void checkTemperature() //method
{
if(temperature > 660)
{
status = "returning home";
speed = 5;
}
}

void showAttributes()
{
System.out.println("Status: " + status);
System.out.println("Speed: " + speed);
System.out.println("Temerature: " + temperature);
}
}


Edit: Hmm strange, without public its still working when i compile it.
Are both .java files in the same directory?

[swappo1]

Please change class to "public class".
I am still getting the same errors with this change.

[baizon]

What (version of) Java are you using?

[swappo1]

Version:

[hopchewer@hopchewer ~]$ java -version
java version "1.6.0_14"
Java(TM) SE Runtime Environment (build 1.6.0_14-b08)
Java HotSpot(TM) Server VM (build 14.0-b16, mixed mode)

[baizon]

Are you sure that the both .java and .class files in the same directory? I've compiled it and on my PC and i didn't get any error messages so the code must be OK.

[swappo1]

Are you sure that the both .java and .class files in the same directory?
Yes.

[hopchewer@hopchewer volcanorobot]$ ls
VolcanoApplication.java VolcanoRobot.class VolcanoRobot.java

I use the gnu compiler for C/C++. Is this using the gnu compiler for java as well? If so, I usually use gcc or g++ for C and C++. Is there something like this for java that I shoul be entering to compile and link the files?

[baizon]

Hmm, try to make a package with this two .java files.
Create a folder "temp" and copy that two .java files into it, then add the first line into this two .java files.



package temp;
class VolcanoApplication {
public static void main(String[] arguments) {
VolcanoRobot dante = new VolcanoRobot();
dante.status = "exploring";
dante.speed = 2;
dante.temperature = 510;

dante.showAttributes();
System.out.println("Increasing speed to 3.");
dante.speed = 3;
dante.showAttributes();
System.out.println("Changing temperature to 670.");
dante.temperature = 670;
dante.showAttributes();
System.out.println("Checking the temperature.");
dante.checkTemperature();
dante.showAttributes();
}

}

[swappo1]

I added the specified line to VolcanoApplication.java, saved both files to /volcanorobot/temp and I got the same results as before. I also tried running the program in netbeans and this is what I got:

Created dir: /home/hopchewer/NetBeansProjects/volcanorobot/build/classes
Created dir: /home/hopchewer/NetBeansProjects/volcanorobot/build/empty
Compiling 2 source files to /home/hopchewer/NetBeansProjects/volcanorobot/build/classes
/home/hopchewer/NetBeansProjects/volcanorobot/src/volcanorobot/Main.java:19: cannot find symbol
symbol : class VolcanoRobot
location: class volcanorobot.Main
VolcanoRobot dante = new VolcanoRobot();
/home/hopchewer/NetBeansProjects/volcanorobot/src/volcanorobot/Main.java:19: cannot find symbol
symbol : class VolcanoRobot
location: class volcanorobot.Main
VolcanoRobot dante = new VolcanoRobot();
2 errors
/home/hopchewer/NetBeansProjects/volcanorobot/nbproject/build-impl.xml:363: The following error occurred while executing this line:
/home/hopchewer/NetBeansProjects/volcanorobot/nbproject/build-impl.xml:168: Compile failed; see the compiler error output for details.
BUILD FAILED (total time: 0 seconds)

Although, this is the first time I have ever used netbeans and I am not at all familiar with it.

[Ragazzo]

Did you try javac VolcanoApplication.java VolcanoRobot.java ie both files as arguments

[credobyte]

Place both files into a separate directory and execute this command from terminal ( don't forget to cd to your newly created directory ):

javac *.java