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POBest way to filter out collections based on certain rules
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2013-11-13T07:23:18.657
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I am trying to find a best way to filter out some items from a list based on certain rules. For example we have <pre><code>public class Person{ String name; String sex; String dob; String contactNo; Person(String name, String sex, String dob, String contactNo) { this.name = name; this.sex = sex; this.dob = dob; this.contactNo = contactNo; } } List<Person> persons = Arrays.asList(new Person("Bob", "male", "19800101", "12345"), new Person("John", "male", "19810101", "12345"), new Person("Tom", "male", "19820101", "12345"), new Person("Helen", "female", "19800101", "12345"), new Person("Jack", "male", "19830101", "12345"), new Person("Suan", "female", "19850101", "12345")); </code></pre> I want to remove the pair of male and female which have the same dob and contactNo (Remove Bob and Helen in above example). I implemented this as below using a nested loop which worked but looks ugly. Is there a better to achieve this please? Can I implement predicate to do this? <pre><code>public void filterPersons() { List<Person> filtered = new ArrayList<Person>(); for (Person p: persons) { boolean pairFound = false; for (Person t: persons) { if ((p.sex.equals("male") && t.sex.equals("female")) || (p.sex.equals("female") && t.sex.equals("male"))) { if (p.dob.equals(t.dob) && p.contactNo.equals(t.contactNo)) { pairFound = true; break; } } } if (!pairFound) {filtered.add(p);} } System.out.println("filtered size is: " + filtered.size()); for (Person p: filtered) { System.out.println(p.name); } } </code></pre> Many thanks. I've rewritten the above method something like below which looks better imho: <pre><code>public void testFilter() { Predicate<Person> isPairFound = new Predicate<Person>() { @Override public boolean apply(Person p) { boolean pairFound = false; for (Person t: persons) { if ((p.sex.equals("male") && t.sex.equals("female")) || (p.sex.equals("female") && t.sex.equals("male"))) { if (p.dob.equals(t.dob) && p.contactNo.equals(t.contactNo)) { pairFound = true; break; } } } return pairFound; } }; Iterable<Person> filtered = Iterables.filter(persons, isPairFound); for (Person p: filtered) { System.out.println(p.name); } } </code></pre>
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<java><collections><predicate>
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Best way to filter out collections based on certain rules
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