String method Append() : StringBuilder vs StringBuffer

Question

With this code:

  public static void main(String[] args) {

    String s = \"Java\";
    StringBuilder buffer = new StringBuilder(s);
    change(buffer);

               


        

Answer 1

StringBuilder does have a constructor accepting a String as an argument, and does have a .charAt() method (which it it must implement since it implements CharSequence).

Conclusion: this is a mishap from the part of your IDE, which did not import the correct StringBuilder. You use another library which has the unfortunate "property" of having implemented a class by the same name -- but not in the same package.

Go see at the top of your file if the import line is:

import java.lang.StringBuilder;