How do I import code?

[Blue1244]

I have two files, one holds the code i want to send to another file how do i do this?
This is the code I have for the main file:

package testingclasses;


public class TestingClasses {

    public static void main(String[] args) {
        //code needs to be imported here.
    }
}

This is the code im trying to import

package testingclasses;

import java.util.Scanner;

public class linearFunction {

    public static void main(String[] args) 
    {
     Scanner scan = new Scanner(System.in);
     System.out.println("You have Chosen the Linear Function Solving!");
     System.out.println("This part of the program is going to ask you for three things, first it is going to ask");
     System.out.println("you for your coefficient, then it is going to ask you for your constant,");
     System.out.println("then it is going to ask you for three numbers that are going to substitute for x.");
     System.out.println();
     System.out.println("Okay here we go!");
     System.out.println("What is your coefficient?");
     double coef = scan.nextDouble();
     System.out.println("");
     System.out.println("What is your constant?");
     double constant = scan.nextDouble();
     System.out.println("What are your three constants?");
     double a = scan.nextDouble();
     double b = scan.nextDouble();
     double c = scan.nextDouble();
     System.out.println("");
     System.out.println("Your function should look like this, y=" + coef + "(x)" + "+" + constant);
     System.out.println("**************************************************************************");
     System.out.println("Your Functions with the x substitutes should look like this...");
     String function1 = "f(x)=" + coef + "(" + a + ")" + "+" + constant;
     String function2 = "f(x)=" + coef + "(" + b + ")" + "+" + constant;
     String function3 = "f(x)=" + coef + "(" + c + ")" + "+" + constant;
     System.out.println("Function 1 => " + function1);
     System.out.println("Function 2 => " + function2);
     System.out.println("Function 2 => " + function3);
     System.out.println("**************************************************************************");
     System.out.println("Your funstion's answers should look like this.");
     System.out.println("**************************************************************************");
     double one = coef * a + constant;
     double two = coef * b + constant;
     double three = coef * c + constant;
     System.out.println("Answer Function 1 =>" + one );
     System.out.println("Answer Function 2 =>" + two );
     System.out.println("Answer Function 3 =>" + three );
     System.out.println("**************************************************************************");
     System.out.println("Your Funstion table should look like this,");
     System.out.println("**************************************************************************");
     System.out.println("X | Y");
     System.out.println(a + "|" + one);
     System.out.println(b + "|" + two);
     System.out.println(c + "|" + three);
     System.out.println("**************************************************************************");
     System.out.println();
     System.out.println("This is other important info");
     System.out.println("**************************************************************************");
     System.out.println("Slope = " + coef );
     System.out.println("Y-intercept = " + constant );
     System.out.println("**************************************************************************");
    }
}

Sorry there is so much code.

[Blue1244]

Oh and if you have any tips on organizing code.. I would be much appreciative.

[Nepomuk]

OK, I'm guessing you're not familiar with the concept of functions and methods? No problem, let me explain:

In any object oriented language (and Java is one of their number), you can write classes (which are a bit like blueprints) and create objects (which are built from these blueprints). These objects can have methods. Projected to the real world a class may be the blueprint of a car (i.e. a Car.java file), an object would be a car built according to the blueprints (Car myCar = new Car();) and a function may be "myCar.driveFor ward()".

In Java, every function must belong to an object or class. Most functions you will use belong to an object, so every time you create a new object it will have its own set of functions. Sometimes however it is necessary for functions to be available without an object; main is a classic example for this. To make a function available without an object, you make it static (that's why it's a public static void); so you can now access Car.main() rather than myCar.main() (though the latter is possible in theory).

The main function is used for the jvm to know where it should start; so main is the function which controls the flow of the program. You will rarely if ever need more than one main function in a program.

So, how do you define new functions? Very easily: do something like this:

package testingclasses;
 
import java.util.Scanner;
 
public class LinearFunction {
 
    public void run() 
    {
     Scanner scan = new Scanner(System.in);
     System.out.println("You have Chosen the Linear Function Solving!");
     System.out.println("This part of the program is going to ask you for three things, first it is going to ask");
     System.out.println("you for your coefficient, then it is going to ask you for your constant,");
     System.out.println("then it is going to ask you for three numbers that are going to substitute for x.");
     System.out.println();
     System.out.println("Okay here we go!");
     System.out.println("What is your coefficient?");
     double coef = scan.nextDouble();
     System.out.println("");
     System.out.println("What is your constant?");
     double constant = scan.nextDouble();
     System.out.println("What are your three constants?");
     double a = scan.nextDouble();
     double b = scan.nextDouble();
     double c = scan.nextDouble();
     System.out.println("");
     System.out.println("Your function should look like this, y=" + coef + "(x)" + "+" + constant);
     System.out.println("**************************************************************************");
     System.out.println("Your Functions with the x substitutes should look like this...");
     String function1 = "f(x)=" + coef + "(" + a + ")" + "+" + constant;
     String function2 = "f(x)=" + coef + "(" + b + ")" + "+" + constant;
     String function3 = "f(x)=" + coef + "(" + c + ")" + "+" + constant;
     System.out.println("Function 1 => " + function1);
     System.out.println("Function 2 => " + function2);
     System.out.println("Function 2 => " + function3);
     System.out.println("**************************************************************************");
     System.out.println("Your funstion's answers should look like this.");
     System.out.println("**************************************************************************");
     double one = coef * a + constant;
     double two = coef * b + constant;
     double three = coef * c + constant;
     System.out.println("Answer Function 1 =>" + one );
     System.out.println("Answer Function 2 =>" + two );
     System.out.println("Answer Function 3 =>" + three );
     System.out.println("**************************************************************************");
     System.out.println("Your Funstion table should look like this,");
     System.out.println("**************************************************************************");
     System.out.println("X | Y");
     System.out.println(a + "|" + one);
     System.out.println(b + "|" + two);
     System.out.println(c + "|" + three);
     System.out.println("**************************************************************************");
     System.out.println();
     System.out.println("This is other important info");
     System.out.println("**************************************************************************");
     System.out.println("Slope = " + coef );
     System.out.println("Y-intercept = " + constant );
     System.out.println("**************************************************************************");
    }
}

and

package testingclasses;
 
 
public class TestingClasses {
 
    public static void main(String[] args) {
        LinearFunction linear = new LinearFunction(); // Create a new object of the type "LinearFunction" called "linear"
        linear.run(); // Call the "run" function of this new object 
    }
}

Note that I changed two things about the first class: I renamed it from "linearFunction " to "LinearFunction " because the convention is to give classes names that start with capital letters and I changed the public static void main(String[] args) to public void run().
Also I added two lines to the main function in the TestingClasses class to use the new run function.

OK, that should be enough to keep you busy for a bit; when you need more help with your code or in case you have difficulties understanding something I wrote, feel free to ask. :-)