indexOf(String str)

int indexOf(String str)

Returns the index within this string of the first occurrence of the specified substring.

int indexOf(String str, int fromIndex)

Returns the index within this string of the first occurrence of the specified substring, starting at the specified index.

public class Main{
  public static void main(String args[]) {
    StringBuffer sb = new StringBuffer();
    sb.append("java2s.com");
    int index = sb.indexOf("a");
    System.out.println(index);
    System.out.println(sb.toString());
    
  }
}

1. Create StringBuffer object
2. append
3. StringBuffer capacity()
4. charAt(int index): get the char at specified index
5. delete(int start, int end) and deleteCharAt(int index)
6. ensureCapacity( )
7. getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin)
8. indexOf(String str)
9. lastIndexOf(String str)
10. StringBuffer length()
11. Insert(): add data in the middle of a StringBuffer
12. replace():replace a StringBuffer
13. StringBuffer reverse()
14. setCharAt(int index, char ch)
15. setLength
16. substring
17. toString():Convert StringBuffer to String