Avoid having Object in the method signature if a more specific type can be used instead.
For example, imagine a simple ReportGenerator class with a generate method that can accept a number of different kinds of objects as parameters to generate a report. It also has a deepClone method to make a copy of the report generator.
public class ReportGenerator
{
public String generate(Object[] parameters)
{
:
}
}
The caller has no idea what kind of parameters the generate() method can accept. A report parameter has some basic attributes, like type and question to display, so it can be encapsulated in a ReportParameter base class.
public class ReportGenerator
{
public String generate(ReportParameter[] parameters)
{
:
}
}
If for some reason, the generate method needed to accept an array of ReportParameter AND String types (hence the original Object parameters), two generate(..) methods should be written.
public class ReportGenerator
{
public String generate(ReportParameter[] parameters)
{
:
}
public String generate(String[] parameters)
{
// convert String[] parameters to ReportParameter types.
ReportParameter[] newParams = new ReportParameter[
parameters.size];
for (int i=0; i<parameters.size; i++)
{
newParameters[i] = new StringParameter(parameters[i]);
}
// call the other main generate method
return generate(newParameters);
}
}
Unless writing for library code where the returned value or parameters can be any type, avoid using Object – use a concrete class instead. If there is a chance for a method to return two different unrelated types, create two methods, but avoid returning Object unless there is no alternative.
Which of these methods would you prefer to see as a caller?
public Object[] getHistory()
{
:
}
public Object deepClone()
{
:
}
The deepClone() method returns a non-specific Object, presumably to future-proof some code that has clearly not been written in a reusable fashion. The following would be much nicer to call.
public HistoryInfo[] getHistory()
{
:
}
public Customer deepClone()
{
:
}
Tip: Always use strongly typed return values if you can. Never return Exception or Object.
