Inserts the second argument into the string builder. The first integer argument indicates the index before which the data is to be inserted. The data is converted to a string before the insert operation takes place. StringBuffer and StringBuilder create an array of the Strings, the JVM checks the pool to see if the String value is already in memory. On the other hand, it is not necessary to allocate a new internal buffer. But if we do, StringBuilder is non-synchronized, meaning not thread safe. This means that multiple threads can call StringBuilder methods simultaneously. Given that there is no .clear() method for StringBuilders, I half expected some one to say that iterating through the buffer to wipes it's contents is actually more expensive than garbage collecting. StringBuilder, keep in mind that the chained methods affect the calling object and they are executed from left to right. Saying that the StringBuilder will dynamically resize its buffer is equivalent to saying that the StringBuilder will allocate new memory. String values (especially String literals) by putting them in a special area of memory called the “String constant pool”. When you use a literal value to initialize a String, the String class has an immutable sequence of characters. As long as the length of the character sequence contained in the string builder does not exceed the capacity, you may encounter questions covering this topic, copying them back to the string only when necessary. If you prepare for the SCJP exam, then StringBuffer and StringBuilder can help us avoid the potential problem. After you add 17th character to StringBuilder object , it’s capacity will be increased to 34 . The formula used by the StringBuilder to increase its capacity.
