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[QUOTE="Abu Yahya, post: 4219294"]
I have a class that instantiates a private member based on a value in a
configuration file.

The value is used to determine the class name.

I initially decided to use code similar to the following:

// class name comes from property file
String dbMgrClassName = props.getProperty("db.manager");
Class<?> k = Class.forName(dbMgrClassName);
db = (DB) k.newInstance();
db.init(props);

However, a colleague pointed out that using "new" is faster than using
"Class.forName().newInstance()". So, I changed the code to the following:

String dbMgrClassName = props.getProperty("db.manager");
if (dbMgrClassName.equals("DB2"))
db = new DB2();
else if  (dbMgrClassName.equals("Oracle"))
db = new Oracle();
else if  (dbMgrClassName.equals("SQLServer"))
db = new SQLServer();
else  { // handle unrecognized
Class<?> k = Class.forName(dbMgrClassName);
db = (DB) k.newInstance();
}
db.init(props);

My question is: Does using if-else statements like the above really
improve performance? What is the best approach to instantiate classes
whose type you don't know at compile time?
[/QUOTE]

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