Transcript Some coding considerations

Some Coding Considerations
Collection Classes
• Use the collection classes in the java.util
package.
• The type declaration should refer to the
interface, not the implementation.
Yes:
import java.util.List;
...
List views = new ArrayList();
No:
ArrayList views = new ArrayList();
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Collection Iteration Idioms
• For standard collection instance, c:
for (Iterator i = c.iterator(); i.hasNext; )
{
doSomething( i.next() );
}
• For high-performance iteration over random
access list, list:
for ( int i = 0, n = list.size(); i < n; i++)
{
doSomething( list.get(i) );
}
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Implementation Order
• For acyclic classes, implement/test
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classes bottom-up.
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• The figure is an example.
– Arcs represent uses relation
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– Node numbers indicate an ordering.
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Implementation Order …
For cyclic classes,
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test nodes referring to each other at
the same time.
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or
1. Test aspects of 4 that do not refer to 5
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2. Test aspects of 5 that do not refer to 4.
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3. Test aspects of 4 that refer to 5.
4. Test aspects of 5 that refer to 4.
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Test-First
• The general class development
algorithm is approximately as follows:
while ( ! class.isComplete )
{
write a little test code;
write the corresponding production code;
}
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Testing …
• Keep a class’s unit test code in either:
– The class’s main method
• Quick & simple
• Not optimized for regression testing
• Increases class’s size, even when not testing.
– A separate class.
• Our Resources page links to http://www.junit.org/.
The Junit Cookbook.
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