java - Print a pattern like AAA to ZZZ starts like AAA AAB AAC.... AAZ ABA ABB ... ZZZ? -

i have tried below code shows error..

        string str="aaa";         char[] ch=str.tochararray();         int length=str.length();         for(int i=length-1;i>=0;i--)         {              for(int j=65;j<=90;j++)              {                  system.out.println(str.replace(ch[i] ,(char)j));              }         } 

all need 3 loops (one each character place):

for(char c1 = 'a'; c1 <= 'z'; c1++){   for(char c2 = 'a'; c2 <= 'z'; c2++){     for(char c3 = 'a'; c3 <= 'z'; c3++){       system.out.println("" + c1 + c2 + c3);     }   }  } 

at end adding string, or else numerical value, instead of string expecting:

system.out.println('a' + 'b' + 'c');  // output: 198 system.out.println("" + 'a' + 'b' + 'c');  // output: abc