finished all of the methods and passed jUnit test

LetterInventory.iml

@@ -24,5 +24,21 @@
         <SOURCES />
       </library>
     </orderEntry>
+    <orderEntry type="module-library" scope="TEST">
+      <library name="JUnit5.8.1">
+        <CLASSES>
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter/5.8.1/junit-jupiter-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-api/5.8.1/junit-jupiter-api-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/opentest4j/opentest4j/1.2.0/opentest4j-1.2.0.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/platform/junit-platform-commons/1.8.1/junit-platform-commons-1.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/apiguardian/apiguardian-api/1.1.2/apiguardian-api-1.1.2.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-params/5.8.1/junit-jupiter-params-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/jupiter/junit-jupiter-engine/5.8.1/junit-jupiter-engine-5.8.1.jar!/" />
+          <root url="jar://$MAVEN_REPOSITORY$/org/junit/platform/junit-platform-engine/1.8.1/junit-platform-engine-1.8.1.jar!/" />
+        </CLASSES>
+        <JAVADOC />
+        <SOURCES />
+      </library>
+    </orderEntry>
   </component>
 </module>

src/driver/Driver.java

@@ -5,8 +5,8 @@
 public class Driver {
 
     public static void main(String[] args) {
-        LetterInventory inv = new LetterInventory();
-        //LetterInventory inv = new LetterInventory("WashingtonState");
+        //LetterInventory inv = new LetterInventory();
+        LetterInventory inv = new LetterInventory("WashingtonState");
         System.out.println(inv);
 
         System.out.println(inv.get('e'));

src/inventory/LetterInventory.java

@@ -33,6 +33,11 @@ public LetterInventory(){
    */
   public LetterInventory(String text) {
    //TODO
+    this();
+    for(int i = 0; i<= text.length()-1; i++){
+      add(text.charAt(i));
+    }
+
   }
 
   /**
@@ -44,9 +49,13 @@ public LetterInventory(String text) {
    * @param c a-z or A-Z character
    * @return index of the character
    */
-  public int getIndex(char c) {
+  public int getIndex(char c)throws IllegalArgumentException{
   //TODO
-    return 0;
+    int num = (int)Character.toUpperCase(c);;
+    if(num >= 'A' && num <= 'Z') {
+      return num - 'A';
+    }
+    throw new IllegalArgumentException("Enter a valid number");
   }
 
   /**
@@ -55,6 +64,7 @@ public int getIndex(char c) {
    */
   public void add(char c) {
 //TODO
+    inventory[getIndex(c)]++;
   }
 
   /**
@@ -63,6 +73,7 @@ public void add(char c) {
    */
   public void subtract(char c) {
   //TODO
+    inventory[getIndex(c)]--;
   }
 
   /**
@@ -71,7 +82,7 @@ public void subtract(char c) {
    */
   public int get(char c) {
    //TODO
-    return 0;
+    return inventory[getIndex(c)];
   }
 
   /**
@@ -80,8 +91,12 @@ public int get(char c) {
    * @param count the number of occurrences of the character c; if count < 0
    *              IllegalArgumentException is thrown
    */
-  public void set(char c, short count) {
+  public void set(char c, short count) throws IllegalArgumentException{
     //TODO
+    if(count < 0){
+      throw new IllegalArgumentException("Please enter a number larger than 0");
+    }
+    inventory[getIndex(c)] = count;
   }
 
   /**
@@ -91,6 +106,9 @@ public void set(char c, short count) {
    */
   public boolean contains(char c) {
     //TODO
+    if(inventory[getIndex(c)] > 0){
+      return true;
+    }
     return false;
   }
 
@@ -100,7 +118,11 @@ public boolean contains(char c) {
    */
   public int size() {
    //TODO
-    return 0;
+    int count = 0;
+    for(int i=0; i<= inventory.length-1; i++){
+      count += inventory[i];
+    }
+    return count;
   }
 
   /**
@@ -109,6 +131,9 @@ public int size() {
    */
   public boolean isEmpty() {
     // TODO
+    if(size() == 0){
+      return true;
+    }
     return false;
   }
 

tests/inventory/LetterInventoryTest.java

@@ -1,12 +1,10 @@
 package inventory;
-
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
 import static org.junit.jupiter.api.Assertions.*;
-
 class LetterInventoryTest {
-/*
+
     static LetterInventory washington;
     static LetterInventory empty;
     static LetterInventory atoz;
@@ -18,6 +16,7 @@ void setUp() {
         atoz = new LetterInventory("abcdefghijklmnopqrstuvwxyz");
     }
 
+
     @Test
     void getIndex() {
         for (int i = 0; i < LetterInventory.ALPHABET_SIZE; i++) {
@@ -125,5 +124,5 @@ void isEmpty() {
         assertFalse(atoz.isEmpty());
         assertFalse(washington.isEmpty());
     }
-*/
+
 }