Question

In a class named MidtermProblems, write a public static method named replaceFirst that takes in a String s and a char c as arguments. The method will return a modified String replacing the first character with the one that was passed in. (Do not print out the String)

Special cases:
If s is null, the method should return null.
If s is the blank string, “”, the method should return the blank string

Answer 1

To solve this problem, you can write a public static method named replaceFirst that takes in a String s and a char c as arguments. The method checks if the input is null or an empty string and returns the respective null or empty string. Otherwise, it constructs a new string by replacing the first character with the one passed in.

Step-by-step explanation:

To solve this problem, you can write a public static method named replaceFirst in the MidtermProblems class that takes in a String s and a char c as arguments. Here is an example of how the method can be implemented in Java:

public static String replaceFirst(String s, char c) {
if (s == null) {
return null;
}
if (s.equals("")) {
return "";
}
return c + s.substring(1);
}

In this implementation, the method checks if the input String s is null or an empty string. If it is, the method returns the respective null or empty string. Otherwise, the method constructs a new string by concatenating the input char c with the substring of s starting from the index 1, effectively replacing the first character.