The StringBuffer class

The base.StringBuffer class is a built-in class designed to manipulate character strings.

This class is optimized for string operations such as scanning, replacements, concatenation.

Use the base.StringBuffer class instead of STRING variables to implement heavy-duty string manipulations. When you use a base.StringBuffer object, you work directly on the internal string buffer. When you use the STRING data type and modify a string, the runtime system creates a new buffer. While this does not impact the performance of programs with a user interface or even batch programs doing SQL, it can impact performance when you need to rapidly process large character strings.

For example, you get much better performance with a base.StringBuffer object than with a STRING variable when you need to:
  • Process 500 KB of text (such as when you are performing a global search-and-replace of specific words).
  • Concatenate many strings.

When you pass a base.StringBuffer object as a function parameter, the function receives a variable that references the object. Passing the object by reference is much more efficient than using a STRING that is passed by value, because STRING data is copied on the stack. The function manipulates the original string, not a copy of the string.


The methods of this class use character positions and string length. When using byte length semantics, the length is expressed in bytes. When using char length semantics, the unit is characters. This matters when using a multibyte locale such as UTF-8.