Click here to watch in Youtube :
https://www.youtube.com/watch?v=OW-kYYCc0zg&list=UUhwKlOVR041tngjerWxVccw

Click the below Image to Enlarge

Java Tutorial : Java StringBuilder [indexOf(String str) method]

StringBuilderDemo.java

/*
 * public int indexOf(String str)
 * 
 * Parameters: 
 * ----------
 * str - any string.
 * 
 * Returns: 
 * ------- 
 * if the string argument occurs as a
 * substring within this object, then the index of the
 * first character of the first such substring is
 * returned; if it does not occur as a substring, -1 is
 * returned.
 */
public class StringBuilderDemo
{

    public static void main(String[] args)
    {

        String str = "Welcome.com";
        StringBuilder sb = new StringBuilder(str);

        int indexPosition = sb.indexOf("com"); // returns 3
        System.out.println("indexOf(\"com\") = " + indexPosition);

        indexPosition = sb.indexOf("abc");// returns -1
        System.out.println("indexOf(\"abc\") = " + indexPosition);

    }
}