Browsing the CVS sources I noticed the use of patterns
which cause unnecessary object creations.

1. String and StringBuffer:

Not optimal code:

String sql = selectClause;
sql += whereClause;
sql += orderByClause;
...

this generates the following code:

String sql = selectClause;
sql = new
StringBuffer(sql).append(whereClause).toString();
sql =
StringBuffer(sql).append(orderByClause).toString();
...

to avoid the unnecessary StringBuffer creation and
enlargement (new char[] creation) a pattern like the
following should be used:

// The initial size of the internal char array should
// be specified as needed or better be calculated a
// priori, for example:
// int len = selectClause.length() +
whereClause.length() ...
StringBuffer sb = new StringBuffer(100);
sb.append(selectClause);
sb.append(whereClause);
sb.append(orderByClause);
String sql = sb.toString();



2. Another place where object creations could be
avoided are ArrayList creations.

Not optimal code:

ArrayList params = new ArrayList();
if (<condition1>)
params.add(<param1>);
if (<condition2>)
params.add(<param2>);
...
foo(..., params, ...);
...

Optimized code:

ArrayList params = null;
if (<condition1>) {
if (params == null)
params = new ArrayList();
params.add(<param1>);
}
if (<condition2>) {
if (params == null)
params = new ArrayList();
params.add(<param2>);
}
...
foo(..., params, ...);
...

Of course all methods have to accept null parameters
to avoid the need to create empty (dummy) objects.



3. Checking for empty strings:

Not ideal code:

if (!str.equals("")) {
...
}

Better:

if (str != null && str.length() > 0) {
...
}


Java is a high level language and a lot of things are
done behind the scenes. But considering these and
others while coding can make even a Java app
efficient.

Best regards
Patrick

__________________________________________________
Do You Yahoo!?
Yahoo! Autos - Get free new car price quotes
http://autos.yahoo.com