Question

I keep coming across techniques like the code below where i need to filter out a type of enumeration from a list.

Are there any more efficent ways to do this?

    private List<TestResult> removeInfo(List<TestResult> testResults) {
    List<TestResult> tmpT = new ArrayList<TestResult>();
    for(TestResult t : testResults) {
        if(!t.getSeverity().equals(Severity.INFO)) {
            tmpT.add(t);
        }
    }
    return tmpT;
}

Collections would be my first thought but not sure.

Cheers
D

Answer 1

You can filter the list in-place using an iterator:

Iterator<TestResult> iterator = testResults.iterator();
while(iterator.hasNext()) {
    TestResult result = iterator.next();
    if (!result.getSeverity().equals(Severity.INFO)) {
        iterator.remove();
    }
}

//Now testResults contains all elements that do not have Severity of INFO

This is an example of Marvo’s comment. It’s more memory efficient but just time efficient as your code. Again, as Marvo said you could some improvement by using a LinkedList. However, unless you’re dealing with huge lists of data I don’t think you’ll notice a difference.