Java Constructor Style (Check parameters aren't null)
- by Peter
What are the best practices if you have a class which accepts some parameters but none of them are allowed to be null?
The following is obvious but the exception is a little unspecific:
public class SomeClass
{
public SomeClass(Object one, Object two)
{
if (one == null || two == null)
{
throw new IllegalArgumentException("Parameters can't be null");
}
//...
}
}
Here the exceptions let you know which parameter is null, but the constructor is now pretty ugly:
public class SomeClass
{
public SomeClass(Object one, Object two)
{
if (one == null)
{
throw new IllegalArgumentException("one can't be null");
}
if (two == null)
{
throw new IllegalArgumentException("two can't be null");
}
//...
}
Here the constructor is neater, but now the constructor code isn't really in the constructor:
public class SomeClass
{
public SomeClass(Object one, Object two)
{
setOne(one);
setTwo(two);
}
public void setOne(Object one)
{
if (one == null)
{
throw new IllegalArgumentException("one can't be null");
}
//...
}
public void setTwo(Object two)
{
if (two == null)
{
throw new IllegalArgumentException("two can't be null");
}
//...
}
}
Which of these styles is best? Or is there an alternative which is more widely accepted?
Cheers,
Pete
