Java errors

Here is the entire code, and the new error. Does the main method need to be in the "Box" class? I need the second class to test the constructors to make sure they all work properly, that is what the book wants me to do.

Code:

---

// Program that ues constructors to assig values (length, width and height) to a box

import javax.swing.JOptionPane;

// Create "Box" class
public class Box
{
        // Declare variables
        private int length;
        private int width;
        private int height;
       
        // Constructors to set length, width, and height
        public Box(int length)
        {
                this.length = length;
                this.width = 0;
                this.height = 0;               
                               
                // Display box length
                JOptionPane.showMessageDialog(null, "Line created with length " + length);
               
    }
        public Box(int  length, int width)
        {
                this.length = length;
                this.width = width;
                this.height = 0;
                               
                // Display box length and width
                JOptionPane.showMessageDialog(null, "Rectangle created with length " + length + " and width " + width);
               
    }
       
                public Box(int  length, int width, int height)
        {
                this.length = length;
                this.width = width;
                this.height = height;
                               
                // Display box length and width
                JOptionPane.showMessageDialog(null, "Box created with length " + length + ", width " + width + ", and height " + height);
                System.exit(0);       
    }                 
        }
       
        public class BoxTest
        {
        // Main method
        public void main(String[] args)
        {         
                Box boxOne = new Box(1);
                Box boxTwo = new Box(1,2);
                Box boxThree = new Box(1,2,3);
        }
        }

---

Error:

Box.java:53: class BoxTest is public, should be declared in a file named BoxTest.java
public class BoxTest
^
1 error

The error is telling you exactly what is wrong.

Although there are ways to have multiple classes in one file in Java, it compiles faster and is typically considered good practice to have each class in its own file that has the same name.

So your "Box" class should be in Box.java and your "BoxTest" class should be in BoxTest.java.

You can tie the two classes together by having them in the same package.

Here is your code, split into 2 files:

Box.java

Code:

---

package smitty.com;

//Program that ues constructors to assig values (length, width and height) to a box

import javax.swing.JOptionPane;

// Create "Box" class
public class Box
{
        // Declare variables
        private int length;
        private int width;
        private int height;
       
        // Constructors to set length, width, and height
        public Box(int length)
        {
                this.length = length;
                this.width = 0;
                this.height = 0;               
                               
                // Display box length
                JOptionPane.showMessageDialog(null, "Line created with length " + length);
               
    }
        public Box(int  length, int width)
        {
                this.length = length;
                this.width = width;
                this.height = 0;
                               
                // Display box length and width
                JOptionPane.showMessageDialog(null, "Rectangle created with length " + length + " and width " + width);
               
    }
       
                public Box(int  length, int width, int height)
        {
                this.length = length;
                this.width = width;
                this.height = height;
                               
                // Display box length and width
                JOptionPane.showMessageDialog(null, "Box created with length " + length + ", width " + width + ", and height " + height);
                System.exit(0);       
    }                 
        }

---

BoxTest.java

Code:

---

package smitty.com;

public class BoxTest
{
 // Main method
 public void main(String[] args)
{         
        Box boxOne = new Box(1);
        Box boxTwo = new Box(1,2);
        Box boxThree = new Box(1,2,3);
}
}

---

I got it all in one file. Thanks for the help. I am getting another error, though now.

ERROR (on run, not compile...there are no compile errors):

----jGRASP exec: java Box

java.lang.NoSuchMethodError: main
Exception in thread "main"
----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.

Looks to me like you're trying to run your "Box" class which has no main, so the program doesn't know where to start.

You need to be running your BoxTest class, since it is the entry point for the program.