OPT.USB

Use `StringBuffer' instead of `String' for non-constant strings

Description

This rule flags code that uses `String' instead of `StringBuffer' for non-constant strings.

Although the += operator is provided by the `String' class, it is much less efficient than the `StringBuffer.append()' function. Using `StringBuffer' instead of using "+=" on `String' objects will improve performance.

Example

 package OPT;
 
 class USB {
    public String foobar() {
        String fruit = "apples";
        fruit+= ", bananas";             // Violation
        return fruit;
    }
 }

Repair

 public String betterFoobar() {
        StringBuffer fruit = new StringBuffer("apples");
        fruit.append(", bananas");
        return fruit.toString();
    }

Reference

Haggar, Peter. Practical Java - Programming Language Guide. Addison Wesley, 2000, pp.107 - 109