isNumber check for String in java

static boolean isNumber(String number){

  if(number.charAt(0)=='-'){

   for(int i = 1 ; i < number.length() ; i++){
    if( Character.isDigit(number.charAt(i))){

    }
    else{
     return false;
    }
   }
  }
  else{

   for(int i = 0 ; i < number.length() ; i++){
    if( Character.isDigit(number.charAt(i))){

    }
    else{
     return false;
    }
   }

  }

  return true;
 }

Well the above code can be simplified alot with the use of ternary operator

 static boolean isNumber(String number){

  for(int i = number.charAt(0)=='-' ? 1: 0 ; i < number.length() ; i++){
    if( Character.isDigit(number.charAt(i))){
    }
    else{
     return false;
    }
   }
  return true;
  
 }