java - Guess Attempts loop issue -

okay have loop isssues first if enter invalid character want program loop , re-ask user input

public boolean isvalid(){   if (letter1.equals('a')|| letter1.equals('b')|| letter1.equals('c')|| letter1.equals('d')|| letter1.equals('e')){      boolean isvalid = true; } else if(letter2.equals('a')|| letter2.equals('b')|| letter2.equals('c')|| letter2.equals('d')|| letter2.equals('e')){     boolean isvalid = true; } else if(letter3.equals('a')|| letter3.equals('b')|| letter3.equals('c')|| letter3.equals('d')|| letter3.equals('e')){     boolean isvalid = true;  } else {     boolean isvalid = false;  }   while (isvalid == false){     system.out.println("invalid input try again");     system.out.println("enter guess #1");     guess = keyboard.nextline();     guess.tolowercase();     letter1 = guess.charat(0);     letter2 = guess.charat(1);     letter3 = guess.charat(2);   } return isvalid; } 

now other problem i'm trying create guess counter user limited 6 guesses , after sixth guess user loses. i'm not sure how i'd loop checkgues in because while loop ins't working.

public void getguess(){ guessatt = 0;     {         if(letter1 == a){              la1 = true;         }         else if(letter1 == b || letter1 == c){              la2 = true;                     }         else if (letter1 != && letter1 != b && letter1 != c){              la3 = true;         }         //letter2          if(letter2 == b){             lb1 = true;         }         else if(letter2 == || letter2 == c){              lb2 = true;          }         else if (letter2 != && letter2 != b && letter2 != c){              lb3 = true;         }         //letter3         if(letter3 == c){              lc1 = true;      }         else if(letter3 == || letter3 == b){              lc2 = true;          }         else if (letter3 != && letter3 != b && letter3 != c){              lc3 = false;         }             //output             if(la1 == true && lb1 == true && lc3 == true){                 system.out.println("2 right letter in right place");                 system.out.println("0 right letter in wrong place");                     }             else if(la1 == true && lb3 == true && lc1 == true){                 system.out.println("2 right letter in right place");                 system.out.println("0 right letter in wrong place");                     }             else if(la1 == true && lb2 == true && lc2 == true){                 system.out.println("1 right letter in right place");                 system.out.println("2 right letter in wrong place");                     }             else if(la1 == true && lb2 == true && lc3 == true){                 system.out.println("1 right letter in right place");                 system.out.println("1 right letter in wrong place");                     }             else if(la1 == true && lb3 == true && lc2 == true){                 system.out.println("1 right letter in right place");                 system.out.println("1 right letter in wrong place");                     }             else if(la2 == true && lb2 == true && lc2 == true){                 system.out.println("0 right letter in right place");                 system.out.println("3 right letter in wrong place");             }             else if(la2 == true && lb2 == true && lc1 == true){                 system.out.println("1 right letter in right place");                 system.out.println("2 right letter in wrong place");                     }             else if(la2 == true && lb1 == true && lc2 == true){                 system.out.println("1 right letter in right place");                 system.out.println("2 right letter in wrong place");                     }             else if(la3 == true && lb3 == true && lc3 == true){                 system.out.println("0 right letter in right place");                 system.out.println("0 right letter in wrong place");                 }             else if(la3 == true && lb1 == true && lc3 == true){                 system.out.println("1 right letter in right place");                 system.out.println("0 right letter in wrong place");                     }             else if(la3 == true && lb3 == true && lc1 == true){                 system.out.println("1 right letter in right place");                 system.out.println("0 right letter in wrong place");                     }     guessatt++;     } while (guessatt < 7);          } 

this of code incase,

import java.util.scanner; import ja va.util.random;  public class codebreaker {     private character letter1;     private character letter2;     private character letter3;     private boolean done;     private boolean isvalid;     private boolean la1,la2,la3,lb1,lb2,lb3,lc1,lc2,lc3;      private string guess;     public  int a, b, c;     private int i,j,guessatt;       static scanner keyboard = new scanner (system.in);     public static void main(string[] args) {         codebreaker code = new codebreaker();         code.codeletter();         code.codebreaker();         code.getguess();         code.display();       }     public void codeletter(){         random r1 = new random();         = r1.nextint(5) + (byte)'a';         random r2 = new random();         b = r2.nextint(5) + (byte)'a';         random r3 = new random();         c = r3.nextint(5) + (byte)'a';       }     public void codebreaker(){         system.out.println("welcome codebreaker");         system.out.println("you have 6 tries find secret 3 letter code");         system.out.println("the letters range e");         system.out.println("good luck");         system.out.println("the code can have repeat letters");         system.out.print("\n");          system.out.println("enter guess #1");         guess = keyboard.nextline();         guess.tolowercase();         letter1 = guess.charat(0);         letter2 = guess.charat(1);         letter3 = guess.charat(2);   }     public boolean isvalid(){       if (letter1.equals('a')|| letter1.equals('b')|| letter1.equals('c')|| letter1.equals('d')|| letter1.equals('e')){          boolean isvalid = true;     }     else if(letter2.equals('a')|| letter2.equals('b')|| letter2.equals('c')|| letter2.equals('d')|| letter2.equals('e')){         boolean isvalid = true;     }     else if(letter3.equals('a')|| letter3.equals('b')|| letter3.equals('c')|| letter3.equals('d')|| letter3.equals('e')){         boolean isvalid = true;      }     else {         boolean isvalid = false;      }       while (isvalid == false){         system.out.println("invalid input try again");         system.out.println("enter guess #"+ guessatt);         guess = keyboard.nextline();         guess.tolowercase();         letter1 = guess.charat(0);         letter2 = guess.charat(1);         letter3 = guess.charat(2);       }     return isvalid;     }     public void getguess(){         guessatt = 0;         {             if(letter1 == a){                  la1 = true;             }             else if(letter1 == b || letter1 == c){                  la2 = true;                         }             else if (letter1 != && letter1 != b && letter1 != c){                  la3 = true;             }             //letter2              if(letter2 == b){                 lb1 = true;             }             else if(letter2 == || letter2 == c){                  lb2 = true;              }             else if (letter2 != && letter2 != b && letter2 != c){                  lb3 = true;             }             //letter3             if(letter3 == c){                  lc1 = true;          }             else if(letter3 == || letter3 == b){                  lc2 = true;              }             else if (letter3 != && letter3 != b && letter3 != c){                  lc3 = false;             }                 //output                 if(la1 == true && lb1 == true && lc3 == true){                     system.out.println("2 right letter in right place");                     system.out.println("0 right letter in wrong place");                         }                 else if(la1 == true && lb3 == true && lc1 == true){                     system.out.println("2 right letter in right place");                     system.out.println("0 right letter in wrong place");                         }                 else if(la1 == true && lb2 == true && lc2 == true){                     system.out.println("1 right letter in right place");                     system.out.println("2 right letter in wrong place");                         }                 else if(la1 == true && lb2 == true && lc3 == true){                     system.out.println("1 right letter in right place");                     system.out.println("1 right letter in wrong place");                         }                 else if(la1 == true && lb3 == true && lc2 == true){                     system.out.println("1 right letter in right place");                     system.out.println("1 right letter in wrong place");                         }                 else if(la2 == true && lb2 == true && lc2 == true){                     system.out.println("0 right letter in right place");                     system.out.println("3 right letter in wrong place");                 }                 else if(la2 == true && lb2 == true && lc1 == true){                     system.out.println("1 right letter in right place");                     system.out.println("2 right letter in wrong place");                         }                 else if(la2 == true && lb1 == true && lc2 == true){                     system.out.println("1 right letter in right place");                     system.out.println("2 right letter in wrong place");                         }                 else if(la3 == true && lb3 == true && lc3 == true){                     system.out.println("0 right letter in right place");                     system.out.println("0 right letter in wrong place");                     }                 else if(la3 == true && lb1 == true && lc3 == true){                     system.out.println("1 right letter in right place");                     system.out.println("0 right letter in wrong place");                         }                 else if(la3 == true && lb3 == true && lc1 == true){                     system.out.println("1 right letter in right place");                     system.out.println("0 right letter in wrong place");                         }         guessatt++;         } while (guessatt < 7);              }           public boolean done(){         if (la1 == true && lb1 == true && lc1 == true){             done = true;         }         else{             done = false;         }     return done;     }      public void display(){         if (done == true){             system.out.println("you win");          }         else{             system.out.println(" try again");         }     }         }