Created
October 18, 2011 21:01
-
-
Save arouel/1296708 to your computer and use it in GitHub Desktop.
Examples for an initialized list to replace element on a particular position.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| package de.rouel; | |
| import java.util.ArrayList; | |
| import java.util.Arrays; | |
| import java.util.List; | |
| import junit.framework.Assert; | |
| import org.junit.Test; | |
| /** | |
| * How can you setup a list with one or more elements at a particular position (index), without having to add elements | |
| * to these position with <code>List.add(T element)</code>? | |
| * | |
| * @see java.util.List#add(Object) | |
| * | |
| * @author André Rouél | |
| */ | |
| public class ListTest { | |
| /** | |
| * This test shows an easier initialization to replace elements on an expected position in a <code>List</code>. | |
| */ | |
| @Test | |
| public void testGetByIndexInitiallyFilled() { | |
| final String[] l = new String[11]; | |
| final List<String> list = new ArrayList<String>(Arrays.asList(l)); | |
| // adds an element for index 3, and now you can replace it with set(idx, string) | |
| list.set(3, "test on index 3"); | |
| // adds an element for index 10, and now you can replace it with set(idx, string) | |
| list.set(10, "test on index 10"); | |
| Assert.assertEquals("test on index 10", list.get(10)); | |
| Assert.assertEquals("test on index 3", list.get(3)); | |
| Assert.assertNull(list.get(0)); | |
| Assert.assertNull(list.get(2)); | |
| Assert.assertNull(list.get(7)); | |
| list.remove(3); | |
| Assert.assertNull(list.remove(3)); | |
| } | |
| /** | |
| * Of course an empty list throws an <code>IndexOutOfBoundsException</code> if you want to get an element of an | |
| * non-existent position. | |
| */ | |
| @Test(expected = IndexOutOfBoundsException.class) | |
| public void testGetByIndexOnEmptyList() { | |
| final List<String> list = new ArrayList<String>(); | |
| list.get(3); | |
| } | |
| /** | |
| * This way you get an initialized list of strings with 11 <code>null</code>-elements. | |
| */ | |
| @Test | |
| public void testGetByIndexOnInitializedList() { | |
| final String[] l = new String[11]; | |
| final List<String> list = new ArrayList<String>(Arrays.asList(l)); | |
| Assert.assertNull(list.get(10)); | |
| } | |
| /** | |
| * This test shows an complicated way to replace elements on an expected position in a <code>List</code>.<br> | |
| * <br> | |
| * <b>Attention</b>: This way is not recommended! | |
| */ | |
| @Test | |
| public void testGetByIndexOnManuallyFilledList() { | |
| final List<String> list = new ArrayList<String>(10); | |
| list.add(null); | |
| list.add(null); | |
| list.add(null); | |
| // adds an element for index 3, and now you can replace it with set(idx, string) | |
| list.add(null); | |
| list.set(3, "test on index 3"); | |
| list.add(null); | |
| list.add(null); | |
| list.add(null); | |
| list.add(null); | |
| list.add(null); | |
| list.add(null); | |
| // adds an element for index 10, and now you can replace it with set(idx, string) | |
| list.add(null); | |
| list.set(10, "test on index 10"); | |
| Assert.assertEquals("test on index 10", list.get(10)); | |
| Assert.assertEquals("test on index 3", list.get(3)); | |
| Assert.assertNull(list.get(0)); | |
| Assert.assertNull(list.get(2)); | |
| Assert.assertNull(list.get(7)); | |
| list.remove(3); | |
| Assert.assertNull(list.remove(3)); | |
| } | |
| } |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment