All the test passed for FirstAssignment- Peiwen Du

GetSecondToLastElement.java

@@ -10,6 +10,7 @@ public void testGetSecondToLastElement1() {
         String[] array = {"the", "man", "of", "steel", "fights", "a", "never-ending", "battle", "for","truth"};
         String expected = "for";
         String actual = StringArrayUtils.getSecondToLastElement(array);
+        System.out.println(actual);
         Assert.assertEquals(expected, actual);
     }
 

ReverseTest.java

@@ -7,7 +7,7 @@
  * Created by super-yang on 03/05/2020.
  */
 
-public class ReverseTest {
+public class ReverseTest extends StringArrayUtils {
 
     @Test
     public void testReverse1() {

StringArrayUtils.java

@@ -1,5 +1,5 @@
 
-
+import java.util.*;
 /**
  * Created by Yang on 1/23/20.
  */
@@ -9,31 +9,31 @@ public class StringArrayUtils {
      * @return first element of specified array
      */ // TODO
     public static String getFirstElement(String[] array) {
-        return null;
+        return array==null?null:array[0];
     }
 
     /**
      * @param array array of String objects
      * @return second element in specified array
      */
     public static String getSecondElement(String[] array) {
-        return null;
+        return array==null||array.length<1?null:array[1];
     }
 
     /**
      * @param array array of String objects
      * @return last element in specified array
      */ // TODO
     public static String getLastElement(String[] array) {
-        return null;
+        return array==null?null:array[array.length-1];
     }
 
     /**
      * @param array array of String objects
      * @return second to last element in specified array
      */ // TODO
     public static String getSecondToLastElement(String[] array) {
-        return null;
+        return array==null||array.length==1?null:array[array.length-2];
     }
 
     /**
@@ -42,6 +42,9 @@ public static String getSecondToLastElement(String[] array) {
      * @return true if the array contains the specified `value`
      */ // TODO
     public static boolean contains(String[] array, String value) {
+        for(String str:array){
+            if(str.equals(value)) return true;
+        }
         return false;
     }
 
@@ -50,23 +53,50 @@ public static boolean contains(String[] array, String value) {
      * @return an array with identical contents in reverse order
      */ // TODO
     public static String[] reverse(String[] array) {
-        return null;
+        if(array==null) return null;
+        int i=0,j=array.length-1;
+        while(i<j){
+            String temp = array[i];
+            array[i] = array[j];
+            array[j] = temp;
+            i++;
+            j--;
+        }
+        return array;
     }
 
     /**
      * @param array array of String objects
      * @return true if the order of the array is the same backwards and forwards
      */ // TODO
     public static boolean isPalindromic(String[] array) {
-        return false;
+        if(array==null) return true;
+        int i=0,j=array.length-1;
+        while(i<j){
+            if(!array[i].equals(array[j])) return false;
+            i++;
+            j--;
+        }
+        return true;
     }
 
     /**
      * @param array array of String objects
      * @return true if each letter in the alphabet has been used in the array
      */ // TODO
     public static boolean isPangramic(String[] array) {
-        return false;
+        Set<Character> set = new HashSet();
+        for(int i=0;i<26;i++){
+            set.add((char)('a'+i));
+        }
+        for(String str:array){
+            str = str.toLowerCase();
+            for(int i=0;i<str.length();i++)
+                if(set.contains(str.charAt(i))){
+                    set.remove(str.charAt(i));
+                }
+        }
+        return set.isEmpty()?true:false;
     }
 
     /**
@@ -75,7 +105,12 @@ public static boolean isPangramic(String[] array) {
      * @return number of occurrences the specified `value` has occurred
      */ // TODO
     public static int getNumberOfOccurrences(String[] array, String value) {
-        return 0;
+        int count = 0;
+        if(array==null) return count;
+        for(String str:array){
+            if(str.equals(value)) count++;
+        }
+        return count;
     }
 
     /**
@@ -84,23 +119,56 @@ public static int getNumberOfOccurrences(String[] array, String value) {
      * @return array with identical contents excluding values of `value`
      */ // TODO
     public static String[] removeValue(String[] array, String valueToRemove) {
-        return null;
+        if (array==null) return null;
+        int deleteIndex = -1;
+        for(int i=0;i<array.length;i++){
+            if(array[i].equals(valueToRemove)){
+                deleteIndex = i;
+                break;
+            }
+        }
+        while(deleteIndex!=-1&&deleteIndex<array.length-1){
+            array[deleteIndex] = array[deleteIndex+1];
+            deleteIndex++;
+        }
+        return Arrays.copyOfRange(array,0,array.length-1);
     }
 
     /**
      * @param array array of chars
      * @return array of Strings with consecutive duplicates removes
      */ // TODO
     public static String[] removeConsecutiveDuplicates(String[] array) {
-        return null;
+        if(array==null) return null;
+        int i=0;
+        for(int j=0;j<array.length;j++){
+            if(!array[j].equals(array[i])){
+                array[++i] = array[j];
+            }
+        }
+        return Arrays.copyOfRange(array,0,i+1);
     }
 
     /**
      * @param array array of chars
      * @return array of Strings with each consecutive duplicate occurrence concatenated as a single string in an array of Strings
      */ // TODO
     public static String[] packConsecutiveDuplicates(String[] array) {
-        return null;
+        if(array==null) return null;
+        int i =0;
+        String before=array[0];
+        StringBuilder sb = new StringBuilder();
+        for(int j=0;j<array.length;j++){
+
+            if(!array[j].equals(before)){
+                before = array[j];
+                array[i++] = sb.toString();
+                sb.setLength(0);
+            }
+            sb.append(array[j]);
+        }
+        array[i++] = sb.toString();
+        return Arrays.copyOfRange(array,0,i);
     }