Please explain what each one does and why we use it in operating systems

3 public class stringbufferEx lic static void main (String arga[1 stringbufferex stringbutterEestringbutfertx atringaufterix.proceed ) private void proceed ingBuffer stringBuffer new stringBuffer Initial value) System.out.printinistring, format (.8-35s ?s- .with inital value: ,, stringBuffer) r.setLength(o) //Setting the lenght to zero (0), which wil1 also rintin (String.format (-358tAfter setting the lenght to zero clear the contents of the stringBuffer System out stringBuffer.append ("New value") system.out.printin(string.format ("-35s , stringBuffer)) "with new value: stringbutfer))