java学习（一）

java学习记录（一）

import java.util.Scanner;
import java.util.ArrayList;
import java.util.Random;
import java.util.*;
import java.util.Date;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class encode
{  
   private static ArrayList<String> arr = new ArrayList(26);
   private static ArrayList<String> arr1 = new ArrayList(26);
   private static ArrayList<String> arr2 = new ArrayList(10);
   private static Random random = new Random();
   public static void prepare()
   {
   Collections.addAll(arr,"a","b","c","d","e","f",
      "g","h","i","j","k","l","m","n","o"
      ,"p","q","r","s","t","u","v","w","x","y","z");
   Collections.addAll(arr1,"A","B","C","D","E","F",
      "G","H","I","J","K","L","M","N","O"
      ,"P","Q","R","S","T","U","V","W","X","Y","Z");
   Collections.addAll(arr2,"0","1","2","3","4","5",
      "6","7","8","9");
   }
   public static String alphabet(int number, String type)
   {
      if(type == "lower" && (number>= 1 && number<= 26))
         return (String)arr.get(number-1);
      else if(type == "upper" && (number>= 1 && number<= 26))
         return (String)arr1.get(number-1);
      else if(type == "number" && (number>= 0 && number<= 9))
         return (String)arr2.get(number);
      else
      {
         System.out.println("Error detected.");
         return "error";
      }
   }
   public static ArrayList getAlphabetLow()
   {  
      return arr;
   }
   public static ArrayList getAlphabetUp()
   {  
      return arr1;
   }
   public static ArrayList getAlphabetNum()
   {  
      return arr2;
   }
   public static String alphabetEncode(String encodeString)
   {
      int index = 0;
      for(int i = 0; i < encodeString.length(); i++)
      {
         String number = encodeString.substring(i,i+1);
         if(arr.contains(number))
         {
            for(int c = 0; c<arr.size(); c++)
            {
               index = (String)arr.get(c)==number ? c : -1;
            }
            index = (index + random.nextInt(25) + 1) % 26;
            number = (String)arr.get(index);
            
         }
         else if(arr1.contains(number))
         {
            for(int c = 0; c<arr1.size(); c++)
            {
               index = (String)arr1.get(c)==number ? c : -1;
            }
            index = (index + random.nextInt(25) + 1) % 26;
            number = (String)arr1.get(index);
         }
         else if(arr2.contains(number))
         {
            for(int c = 0; c<arr2.size(); c++)
            {
               index = (String)arr2.get(c)==number ? c : -1;
            }
            index = (index + random.nextInt(9) + 1) % 10;
            number = (String)arr2.get(index);
         }
         else
         {
            continue;
         }
         encodeString = encodeString.substring(0,i) + number + encodeString.substring(i+1);
      }
      return encodeString;
   }
   public static int findIndex(String letter)
   {
      int index = 0;
      if(arr.contains(letter))
      {
         for(int c = 0; c<arr.size(); c++)
         {
            index = arr.get(c) == letter ? c+1 : 0;
         }
         return index;
      }
      else if(arr1.contains(letter))
      {
         for(int c = 0; c<arr1.size(); c++)
         {
            index = arr1.get(c) == letter ? c+1 : 0;
         }
         return index;
      }
      else if(arr2.contains(letter))
      {
         for(int c = 0; c<arr2.size(); c++)
         {
            index = arr2.get(c) == letter ? c+1 : 0;
         }
         return index;
      }
      else
      {
         return -1;
      }
   }
}