Modify the program in Figure 19 so that if no command-line arguments are given, then the standard input is used. Write a method that returns true if String str1 is a prefix of String str2. Do not use...

Modify the program in Figure 19 so that if no command-line arguments are given, then the standard input is used. Write a method that returns true if String str1 is a prefix of String str2. Do not use any of the general string searching routines except charAt