Learn Java Programming - StringBuilder .insert() Method Tutorial
In this tutorial I will talk about the insert() method. The insert method inserts the value of the parameter into the value of the current StringBuilder object at a specified position. There are a dozen overloaded versions of the insert() method that will allow you to pass in quite a few data types. For example, the insert(int offset, String str) method works like this:
StringBuilder sb = new StringBuilder("0123456789");
sb.insert(4, "ABC");
System.out.println(sb); // 0123ABC456789
The offset parameter is the index of the character sequence of the current StringBuilder object, the insertion will take place after the character specified by the offset. In this case 4 tells the method to insert the String parameter after the character located at the forth index. If you attempt to insert something at an invalid offset, the method will throw a StringIndexOutOfBoundsException.