Lists utility example

There are various places around leveluplunch that show the power of guava's Lists utility class such as functions example, reverse elements in list, partition list, and many places that use Lists.newArrayList(). This example will try to bring a few together on one page.

Create new list

@Test
public void create_new_list () {
    
    List<String> myList = Lists.newArrayList();
    
    assertNotNull(myList);
}

Create new list w/ parameters

@Test
public void create_new_list_with_parameters () {

    List<String> myList = Lists.newArrayList("one", "two");
    
    assertNotNull(myList);
}

Create list with capacity

@Test
public void create_new_list_with_capacity () {

    List<String> listWithSize10 = Lists.newArrayListWithCapacity(10);
    
    assertNotNull(listWithSize10);
    assertEquals(10, listWithSize10);
}

Create new list w/ expected size

@Test
public void create_new_list_with_expected_size () {

    List<String> listWithSize10 = Lists.newArrayListWithExpectedSize(10);
    
    assertNotNull(listWithSize10);
    assertEquals(10, listWithSize10);
}

Unmodifiable list

@Test
public void create_new_unmodified_list () {
    
    String[] vals = {"test1", "test2"};
    List<String> myList = Lists.asList("test0", vals);
    
    assertNotNull(myList);
}

Parition list

@Test
public void partition_list () {
    
    List<String> myList = Lists.newArrayList("one", "two", "three");
    
    List<List<String>> myListBy1 = Lists.partition(myList, 1);

    assertThat(myListBy1.get(0), hasItems("one"));
    assertThat(myListBy1.get(1), hasItems("two"));
    assertThat(myListBy1.get(2), hasItems("three"));
}

Reverse list

@Test
public void reverse_list () {

    List<String> myList = Lists.newArrayList("one", "two", "three");

    List<String> reverseMyList = Lists.reverse(myList);
    
    assertThat(reverseMyList, contains(
             "three", "two", "one"));
}

Transform elements

/**
 * Tranform elements in list
 */
@Test
public void tranform_elements_in_list () {
    
    List<String> numbersAsStrings = Lists.newArrayList(
            "1", "2", "3");
    
    List<Double> doubles = Lists.transform(numbersAsStrings, new Function<String, Double>() {
        @Override
        public Double apply(String input) {
            return new Double(input);
        }
    });
    
    assertThat(doubles, contains(
             new Double(1), new Double(2), 
             new Double(3)));
}