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ordering work

This commit is contained in:
Eugen Paraschiv 2013-10-25 12:01:33 +03:00
parent 8c81ec9e42
commit b19a5af156
1 changed files with 45 additions and 20 deletions
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65
guava/src/test/java/org/baeldung/guava/collections/GuavaOrderingExamplesTest.java
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@ -1,8 +1,8 @@
package org.baeldung.guava.collections;
import static org.hamcrest.Matchers.equalTo;
import static org.hamcrest.Matchers.nullValue;
import static org.junit.Assert.assertThat;
import static org.junit.Assert.assertTrue;
import java.util.Arrays;
import java.util.Collections;
@ -10,47 +10,72 @@ import java.util.List;
import org.junit.Test;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;
import com.google.common.primitives.Ints;
public class GuavaOrderingExamplesTest {
private final class OrderingByLenght extends Ordering<String> {
@Override
public final int compare(final String s1, final String s2) {
return Ints.compare(s1.length(), s2.length());
}
}
// tests
@Test
public final void givenCollectionWithNulls_whenSortingWithNullsLast_thenNullsAreLast() {
final List<Integer> nums = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(nums, Ordering.natural().nullsLast());
assertThat(nums.get(nums.size() - 1), nullValue());
final List<Integer> toSort = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(toSort, Ordering.natural().nullsLast());
assertThat(toSort.get(toSort.size() - 1), nullValue());
}
@Test
public final void givenCollectionWithNulls_whenSortingWithNullsFirst_thenNullsAreFirst() {
final List<Integer> nums = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(nums, Ordering.natural().nullsFirst());
assertThat(nums.get(0), nullValue());
final List<Integer> toSort = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(toSort, Ordering.natural().nullsFirst());
assertThat(toSort.get(0), nullValue());
}
@Test
public final void whenCollectionIsSortedNullsLastReversed_thenNullAreFirst() {
final List<Integer> nums = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(nums, Ordering.natural().nullsLast().reverse());
assertThat(nums.get(0), nullValue());
final List<Integer> toSort = Arrays.asList(3, 5, 4, null, 1, 2);
Collections.sort(toSort, Ordering.natural().nullsLast().reverse());
assertThat(toSort.get(0), nullValue());
}
@Test
public final void givenCollectionIsSorted_whenUsingOrderingApiToCheckOrder_thenCheckCanBePerformed() {
final List<String> toSort = Arrays.asList("zz", "aa", "b", "ccc");
final Ordering<String> byLength = new OrderingByLenght();
Collections.sort(toSort, byLength);
final Ordering<String> expectedOrder = Ordering.explicit(Lists.newArrayList("b", "zz", "aa", "ccc"));
assertTrue(expectedOrder.isOrdered(toSort));
}
@Test
public final void whenSortingCollectionsOfStringsByLenght_thenCorrectlySorted() {
final List<String> toSort = Arrays.asList("aa", "b", null, "ccc");
final Ordering<String> byLength = new Ordering<String>() {
@Override
public int compare(final String s1, final String s2) {
return Ints.compare(s1.length(), s2.length());
}
};
final List<String> toSort = Arrays.asList("zz", "aa", "b", "ccc");
final Ordering<String> byLength = new OrderingByLenght();
Collections.sort(toSort, byLength.nullsFirst());
assertThat(toSort.get(0), nullValue());
assertThat(toSort.get(1), equalTo("b"));
Collections.sort(toSort, byLength);
final Ordering<String> expectedOrder = Ordering.explicit(Lists.newArrayList("b", "zz", "aa", "ccc"));
assertTrue(expectedOrder.isOrdered(toSort));
}
@Test
public final void whenSortingCollectionsOfStringsByLenghtWithSecondaryNaturalOrdering_thenCorrectlySorted() {
final List<String> toSort = Arrays.asList("zz", "aa", "b", "ccc");
final Ordering<String> byLength = new OrderingByLenght();
Collections.sort(toSort, byLength.compound(Ordering.natural()));
final Ordering<String> expectedOrder = Ordering.explicit(Lists.newArrayList("b", "aa", "zz", "ccc"));
assertTrue(expectedOrder.isOrdered(toSort));
}
}