class Buffer{ public static void main(String[]args){ StringBuffer buf = new StringBuffer("hello"); buf.append(","); buf.append("world!"); buf.insert(5,"java"); buf.replace(0,5,"Hi"); buf.delete(7,12); System.out.println(buf); } } class Builder{ public static void main(String[]args){ StringBuilder Builder = new StringBuilder("hello"); Builder.append(","); Builder.append("world!"); Builder.insert(5,"java"); Builder.replace(0,5,"Hi"); Builder.delete(7,12); System.out.println(Builder); } }