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

Make sure that you are not defining your class name as StringBuilder

For Example: Even if you import it correctly

 import java.lang.StringBuilder;

But if you write your class as

 public class StringBuilder { //If class name matches below Object Creation
 public static void main(String[] args) {

String s = "Java";
StringBuilder buffer = new StringBuilder(s);  //Object creation
change(buffer);

   System.out.println("What's strBuf.charAt(5)? " + strBuf.charAt(3));
   System.out.println(buffer);
}

 private static void change(StringBuilder buffer) {

      buffer.append(" and HTML"); //you will get this error at append
  //The method append(String) is undefined for the type StringBuilder
} 
}

Suggestions

Rename your class name to something else but not StringBuilder