Given a string, return a new string where the first and last chars have been exchanged.

FrontBack

//Given a string, return a new string where the first and last chars have been exchanged.

public String frontBack(String str) {
  int n=str.length();
  if(n>=2){
    return str.substring(n-1)+str.substring(1,n-1)+str.substring(0,1);
  }
else 
return str;
  
  
}