Java Basics 1.11

Encapsulation

 

• Encapsulate functions by wrapping sections of code in a class/method
• Now reuseable
• Changing in one place, not many

 

Code:

 

 

Classes

• Class = Filename.java
• Only one public class per java file
• Multiple classes only accessible within the files
• Refactoring is process of pulling code out, creating method/class
  • Also changing class name is refactoring

 

Code:

 

From

                                result = divideValues(s1, s2);

To

                                result = SimpleMath.divideValues(s1, s2);

 

From

----------------------------------------------------------

public class Calculator2 {

 

    private static double divideValues(String s1, String s2) {

                 double d1 = Double.parseDouble(s1);

                 double d2 = Double.parseDouble(s2);

                 double result = d1 / d2;

                 return result;

----------------------------------------------------------

To

----------------------------------------------------------

public class SimpleMath {

 

    public static void main(String[] args) {

 

 

    }

   

    public static double divideValues(String s1, String s2) {

                 double d1 = Double.parseDouble(s1);

                 double d2 = Double.parseDouble(s2);

                 double result = d1 / d2;

                 return result;

----------------------------------------------------------

 

Packages

• If class is anywhere but default package, it must be declared
• when creating packages, use reverse domain...
  • com.silosix.calc

 

 

Importing Packages

package com.lynda.calc;

import com.lynda.calc.helpers.InputHelper;

import com.lynda.calc.helpers.MathHelper;

 

same as:

 

package com.lynda.calc;

import com.lynda.calc.helpers.*;

 

CTRL-O will change * to specific class imports

 

 

 

Refactor > Move