vaidateRow Method

gistfile1.txt

import java.util.Scanner;
 
public class Combine {
   public static void main(String[] argv) {
      Scanner scnr = new Scanner(System.in); // talk to Gabe Monday to better
   											// understand scanner
//      String row = scnr.next();
//   	row = moveLeft(row); // remember to call methods
//      row = combineLeft(row);
//      System.out.print(row);
      System.out.println(combineLeft("_4422")); 
   	// asserts
      assert validateChar('2') : "2 should be a valid char";
      assert validateChar('4') : "4 should be a valid char";
      assert validateChar('_') : "_ should be a valid char";
      assert !validateChar(' ') : "space should not be a valid char";
      assert !validateChar('3') : "3 should not be a valid char";
   
      assert !validateRow("2222") : "2222 should not be valid";
   //		assert !validateRow("__") : "__ should not be valid";
      assert !validateRow("aaa") : "aaa should not be valid";
      assert !validateRow("333") : "333 should not be valid";
      assert validateRow("_2_") : "_2_ should be valid";
      assert validateRow("22_") : "22_ should be valid";
      assert validateRow("242") : "242 should be valid";
   
      assert "4__".equals(combineLeft("__4")) : "__4 doesn't change to 4__";
      assert "8__".equals(combineLeft("_44")) : "_44 doesn't change to 8__";
      assert "4__".equals(combineLeft("2_2")) : "2_2 doesn't change to 4__";
      assert "4__".equals(combineLeft("22_")) : "22_ doesn't change to 4__";
      assert "42_".equals(combineLeft("222")) : "222 doesn't change to 42_";
      assert "44_".equals(combineLeft("422")) : "422 doesn't change to 44_";
      assert "242".equals(combineLeft("242")) : "242 doesn't change to 242";
   
      assert "8__".equals(combineLeft(combineLeft("422"))) : "Double invocation doens't work!";
   
      assert "___".equals(combineLeft("___")) : "___should be invalid!"; 
   
   }
 
   public static boolean validateChar(char ch) {
      if (ch == '2' || ch == '4' || ch == '_' || ch == '8') {
         return true;
      } 
      else {
         return false;
      }
   }
 
   public static boolean validateRow(String row) {
   
      if (((row.charAt(0) == '_' || row.charAt(0) == '2' || row.charAt(0) == '4')) && ((row.charAt(1) == '_' || row.charAt(1) == '2' || row.charAt(1) == '4')) && ((row.charAt(2) == '_' || row.charAt(2) == '2' || row.charAt(2) == '4'))) {
         if(row.length() !=3) {
            return false;
         }
         else if(row == "___") {
            return false;
         }
         else{
            return true;
         }
      }
      else  {
         return false;
      }
     
      
   }
 
   public static String moveLeft(String row) {
   
      if (validateRow(row) == true) {
         row = row.replace("__2", "2__");
         row = row.replace("_2_", "2__");
         row = row.replace("__4", "4__");
         row = row.replace("_4_", "4__");
         row = row.replace("_44", "44_");
      } 
      else {
         return "Not a Valid String";
      }  
   
      return row;
   }
 
   public static String combineLeft(String row) {
      String row2 = moveLeft(row);
      if (validateRow(row2) == true) {
         row2 = row2.replace("22_", "4__");
         row2 = row2.replace("_22", "4__");
         row2 = row2.replace("2_2", "4__");
         row2 = row2.replace("222", "42_");
         row2 = row2.replace("44_", "8__");
         row2 = row2.replace("_44", "8__");
         row2 = row2.replace("4_4", "8__");
         row2 = row2.replace("444", "84_");
         row2 = row2.replace("422", "44_");
         row2 = row2.replace("442", "82_");
         row2 = row2.replace("224", "44_");
         row2 = row2.replace("244", "28_");
      }  
   
      return row2;
   }
}