Need some help coding this string exercise. This file contains a set of static methodss and documentation describing them. Implement each method as described. Thank you!

public class StringExercises {

/**

* Searches for "Marc" in a string.

*

* @param string a non-null string

* @return the index of the first occurrence of "Marc" in string, or -1 if not found

*/

public static int findMarc(String string) {

int index = string.indexOf("Marc");

return index;

}

/**

* Searches for a substring within a string.

* @param string a non-null string

* @param substring a non-null string

* @return the index of the first occurrence of the substring within the string, or -1 if not found

*/

public static int findSubstring(String string, String substring) {

int index = string.indexOf(substring);

return index;

}

/**

* Returns true if and only if the string contains the substring.

* @param string a non-null string

* @param substring a non-null string

* @return true if and only if the string contains the substring

*/

public static boolean contains(String string, String substring) {

int index = string.indexOf(substring);

if(index != -1) {

return true;

}

else {

return false;

}

}

/**

* Splits a string into words, using whitespace to delimit the words.

*

* See the assignment writeup for the magic argument to split().

*

* @param string a non-null string

* @return an array representing the words in the string.

*/

public static String[] splitIntoWords(String string) {

String splitString[] = string.split(" ");

return splitString;

}

/**

* Returns the substring representing the first four characters of the string.

* @param string a non-null string of length >= 4

* @return the substring representing the first four characters of the string

*/

public static String firstFour(String string) {

String result = string.substring(0, 4);

return result;

}

/**

* Returns the substring representing the first n characters of the string.

* @param string a non-null string of length >= n

* @param n an integer >= 0

* @return the substring representing the first n characters of the string

*/

public static String firstN(String string, int n) {

String result = string.substring(0, n);

return result;

}

/**

* Returns the substring representing the last four characters of the string.

* @param string a non-null string of length >= 4

* @return the substring representing the last four characters of the string

*/

public static String lastFour(String string) {

String result = string.substring(string.length()-4);

return result;

}

/**

* Returns the substring representing the last n characters of the string.

* @param string a non-null string of length >= n

* @param n an integer >= 0

* @return the substring representing the last n characters of the string

*/

public static String lastN(String string, int n) {

String result = string.substring(string.length()-n);

return result;

}

}

StringExercises.test

package string.exercises;

import static org.junit.Assert.*;

import org.junit.Rule; import org.junit.Test; import org.junit.rules.Timeout;

public class StringExercisesTest {

// Uncomment these two lines if you want to catch infinite loops // @Rule // public Timeout globalTimeout = Timeout.seconds(10); // 10 seconds

@Test public void testFindMarcEmpty() { assertEquals(-1, StringExercises.findMarc("")); }

@Test public void testFindMarcExact() { assertEquals(0, StringExercises.findMarc("Marc")); }

@Test public void testFindMarc() { assertEquals(0, StringExercises.findMarc("Marc ")); }

@Test public void testFindMarc2() { assertEquals(2, StringExercises.findMarc(" Marc ")); } @Test public void testFindSubstringEmpty() { assertEquals(-1, StringExercises.findSubstring("", "banana")); }

@Test public void testFindSubstringExact() { assertEquals(0, StringExercises.findSubstring("banana", "banana")); }

@Test public void testFindSubstring() { assertEquals(0, StringExercises.findSubstring("banana ", "banana")); }

@Test public void testFindSubstring2() { assertEquals(2, StringExercises.findSubstring(" banana ", "banana")); } @Test public void testFindSubstringBananas() { assertEquals(2, StringExercises.findSubstring(" bananabanana ", "banana")); } @Test public void testContainsEmpty() { assertFalse(StringExercises.contains("", "banana")); }

@Test public void testContainsExact() { assertTrue(StringExercises.contains("foo", "foo")); }

@Test public void testContains() { assertTrue(StringExercises.contains("foo ", "foo")); }

@Test public void testContainsEmbedded() { assertTrue(StringExercises.contains("aasdfsdf", "asdf")); } @Test public void testNotContainsEmbedded() { assertFalse(StringExercises.contains("aasdfsdf", "adsf")); } @Test public void testSplitZero() { assertArrayEquals(new String[] {""}, StringExercises.splitIntoWords("")); }

@Test public void testSplitOne() { assertArrayEquals(new String[] {"banana"}, StringExercises.splitIntoWords("banana")); }

@Test public void testSplitThree() { assertArrayEquals(new String[] {"Larry", "Moe", "Curly"}, StringExercises.splitIntoWords("Larry Moe Curly ")); }

@Test public void testFirstFourExact() { assertEquals("Kate", StringExercises.firstFour("Kate")); }

@Test public void testFirstFour() { assertEquals("Kate", StringExercises.firstFour("Katelyn")); } @Test public void testFirstN() { assertEquals("", StringExercises.firstN("Katelyn", 0)); assertEquals("K", StringExercises.firstN("Katelyn", 1)); assertEquals("Ka", StringExercises.firstN("Katelyn", 2)); assertEquals("Kat", StringExercises.firstN("Katelyn", 3)); assertEquals("Kate", StringExercises.firstN("Katelyn", 4)); assertEquals("Katel", StringExercises.firstN("Katelyn", 5)); assertEquals("Kately", StringExercises.firstN("Katelyn", 6)); assertEquals("Katelyn", StringExercises.firstN("Katelyn", 7)); }

@Test public void testLastFourExact() { assertEquals("Kate", StringExercises.lastFour("Kate")); }

@Test public void testLastFour() { assertEquals("elyn", StringExercises.lastFour("Katelyn")); } @Test public void testLastN() { assertEquals("", StringExercises.lastN("Katelyn", 0)); assertEquals("n", StringExercises.lastN("Katelyn", 1)); assertEquals("yn", StringExercises.lastN("Katelyn", 2)); assertEquals("lyn", StringExercises.lastN("Katelyn", 3)); assertEquals("elyn", StringExercises.lastN("Katelyn", 4)); assertEquals("telyn", StringExercises.lastN("Katelyn", 5)); assertEquals("atelyn", StringExercises.lastN("Katelyn", 6)); assertEquals("Katelyn", StringExercises.lastN("Katelyn", 7)); }}