Encryption and Decryption in Android (Using builder pattern )

The builder pattern is an object creation software design pattern. Unlike the abstract factory pattern and the factory method pattern whose intention is to enablepolymorphism, the intention of the builder pattern is to find a solution to the telescoping constructor anti-pattern. The telescoping constructor anti-pattern occurs when the increase of object constructor parameter combination leads to an exponential list of constructors. Instead of using numerous constructors, the builder pattern uses another object, a builder, that receives each initialization parameter step by step and then returns the resulting constructed object at once.

The builder pattern has another benefit. It can be used for objects that contain flat data (html code, SQL query, X.509 certificate...), that is to say, data that can't be easily edited. This type of data cannot be edited step by step and must be edited at once. The best way to construct such an object is to use a builder class.

Builder often builds a Composite. Often, designs start out using Factory Method (less complicated, more customizable, subclasses proliferate) and evolve towardAbstract Factory, Prototype, or Builder (more flexible, more complex) as the designer discovers where more flexibility is needed. Sometimes creational patterns are complementary: Builder can use one of the other patterns to implement which components are built. Builders are good candidates for a fluent interface.

//Abstract Builder
class abstract class TextConverter{
 abstract void convertCharacter(char c);
 abstract void convertParagraph();
}

// Product
class ASCIIText{
 public void append(char c){ //Implement the code here }
}

//Concrete Builder
class ASCIIConverter extends TextConverter{
 ASCIIText asciiTextObj;//resulting product

 /*converts a character to target representation and appends to the resulting*/
 object void convertCharacter(char c){
  char asciiChar = new Character(c).charValue();
   //gets the ascii character
  asciiTextObj.append(asciiChar);
 }
 void convertParagraph(){}
 ASCIIText getResult(){
  return asciiTextObj;
 }
}

//This class abstracts the document object
class Document{
 static int value;
 char token;
 public char getNextToken(){
  //Get the next token
  return token;
 }
}

//Director
class RTFReader{
 private static final char EOF='0'; //Delimitor for End of File
 final char CHAR='c';
 final char PARA='p';
 char t;
 TextConverter builder;
 RTFReader(TextConverter obj){
  builder=obj;
 }
 void parseRTF(Document doc){
  while ((t=doc.getNextToken())!= EOF){
   switch (t){
    case CHAR: builder.convertCharacter(t);
    case PARA: builder.convertParagraph();
   }
  }
 }
}

//Client
public class Client{
 void createASCIIText(Document doc){
  ASCIIConverter asciiBuilder = new ASCIIConverter();
  RTFReader rtfReader = new RTFReader(asciiBuilder);
  rtfReader.parseRTF(doc);
  ASCIIText asciiText = asciiBuilder.getResult();
 }
 public static void main(String args[]){
  Client client=new Client();
  Document doc=new Document();
  client.createASCIIText(doc);
  system.out.println("This is an example of Builder Pattern");
 }
}