LetterInventory Completed

README.md

@@ -0,0 +1,15 @@
+# LetterInventory
+
+### Description
+This repository holds my submission to an assignment for SDEV301 Systems Programming at Green River College. The purpose of this assignment was to become familiar with the memory impact of using bytes, shorts, and ints via creating methods for `LetterInventory`.
+
+`LetterInventory` is a class that has two constructors - one that takes in no arguments, and one that takes in a String argument. The class keeps track of private inventory, a short[] that keeps track of how many letter counts a string has (case-insensitive).
+
+Each letter should correspond to an index (i.e. a -> 0, b -> 1, c -> 2, d -> 3, and so on).
+
+
+For example:
+- "WashingtonState" would result in `[2,0,0,0,1,0,1,1,1,0,0,0,0,2,1,0,0,0,2,3,0,0,1,0,0,0]`, which wouuld print out as `[aaeghinnosstttw]`.
+
+### How to Run the Project
+This code can be run as-is with the IntelliJ IDEA IDE from Jetbrains, as long as [Java has been installed](https://www.oracle.com/java/technologies/downloads/) locally.

src/driver/Driver.java

@@ -5,13 +5,22 @@
 public class Driver {
 
     public static void main(String[] args) {
-        LetterInventory inv = new LetterInventory();
-        //LetterInventory inv = new LetterInventory("WashingtonState");
+        LetterInventory inv1 = new LetterInventory();
+        System.out.println(inv1);
+
+        LetterInventory inv = new LetterInventory("WashingtonState");
         System.out.println(inv);
 
         System.out.println(inv.get('e'));
-        System.out.println(inv.getIndex('e'));
+        System.out.println(inv.getIndex('e')); //4
+        System.out.println(inv.getIndex('Z')); //25
+//        System.out.println(inv.getIndex('1')); //Throw exception
 
+        //Test add();
+        inv.add('a');
+        System.out.println(inv);
 
+        int temp = 1 << 4;
+        System.out.println("testing bit shift: " + temp);
     }
 }

src/inventory/LetterInventory.java

@@ -1,3 +1,10 @@
+/**
+ * SDEV 301: Systems Programming
+ *
+ * @author Kendrick Hang, Tien Han
+ * @version 1.0
+ */
+
 package inventory;
 
 /**
@@ -14,7 +21,13 @@
  *
  */
 public class LetterInventory  {
-
+  //If this is private int[] inventory - it takes up 32 bits * 26 letters => 832 bits of space
+  //If this is private short[] inventory - it takes upu 16 bits * 26 letters => 416 bits of space
+  //If this is private byte[] inventory - it takes up 8 bits * 26 letters => 208 bits of space
+    //Only want to use byte[] if the letter count < 256
+    //Because 256 is the biggest value you can store with 8 bits
+    //Which is 64 (2^6) + 32  (2^5) + 16 (2^4) + 8 (2^3) + 4 (2^2) + 2 (2^1) + 1 (2^0)
+    //127 bytes per spot in the array (example: so we can only support "a" up to 127)
   private short[] inventory; // inventory is null here
   public static final byte ALPHABET_SIZE = 26;
 
@@ -32,7 +45,14 @@ public LetterInventory(){
    * @param text
    */
   public LetterInventory(String text) {
-   //TODO
+    //this() will call the constructor LetterInventory() to
+    //initialize our inventory short array.
+    this();
+
+    for (int i = 0; i < text.length(); i++) {
+      char letter = text.charAt(i);
+      add(letter);
+    }
   }
 
   /**
@@ -45,33 +65,45 @@ public LetterInventory(String text) {
    * @return index of the character
    */
   public int getIndex(char c) {
-  //TODO
-    return 0;
+    if ((c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z')) {
+      //Subtract 97 as "a" starts at 97 and we want the index to start at 0
+      int index = (int) c - 97;
+      //Adjust for capital letters
+      if (index < 0) {
+        return index + 32;
+      }
+      return index;
+    } else {
+      throw new IllegalArgumentException("The given character " + c + " was a non alpha character.");
+    }
   }
 
   /**
    * Increases the count for the given character in the inventory
    * @param c a-z or A-Z otherwise an IllegalArgumentException is thrown
    */
   public void add(char c) {
-//TODO
+    int index = getIndex(c);
+    int newCount = this.inventory[index] + 1;
+    this.inventory[index] = (short) newCount;
   }
 
   /**
    * Decreases the count for the given character in the inventory
    * @param c a-z or A-Z otherwise an IllegalArgumentException is thrown
    */
   public void subtract(char c) {
-  //TODO
+    int index = getIndex(c);
+    int newCount = this.inventory[index] - 1;
+    this.inventory[index] = (short) newCount;
   }
 
   /**
    * Returns the count for the given character in the inventory
    * @param c a-z or A-Z otherwise an IllegalArgumentException is thrown
    */
   public int get(char c) {
-   //TODO
-    return 0;
+   return this.inventory[getIndex(c)];
   }
 
   /**
@@ -81,7 +113,11 @@ public int get(char c) {
    *              IllegalArgumentException is thrown
    */
   public void set(char c, short count) {
-    //TODO
+    if (count < 0) {
+      throw new IllegalArgumentException("The given count " + count + " is less than 0.");
+    }
+
+    this.inventory[getIndex(c)] = count;
   }
 
   /**
@@ -90,26 +126,32 @@ public void set(char c, short count) {
    * @return true if character is in inventory, false otherwise
    */
   public boolean contains(char c) {
-    //TODO
-    return false;
+      return this.inventory[getIndex(c)] > 0;
   }
 
   /**
    * Return the total count of all letters in the inventory
    * @return total count
    */
   public int size() {
-   //TODO
-    return 0;
+    int counter = 0;
+    for (short count : this.inventory) {
+     counter += count;
+    }
+    return counter;
   }
 
   /**
    * Determine if the inventory has zero counts for all letters
    * @return true, if empty, false otherwise
    */
   public boolean isEmpty() {
-    // TODO
-    return false;
+    for (short count : this.inventory) {
+      if (count > 0) {
+        return false;
+      }
+    }
+    return true;
   }
 
   /**
@@ -142,6 +184,8 @@ public String toString() {
         toReturn.append((char) ('a' + i));
       }
     }
+    //Join in the closing "]"  and convert the StringBuilder
+    //to a String and return it
     return toReturn.append("]").toString();
   }
 

src/inventory/LetterPresence.java

@@ -0,0 +1,42 @@
+/**
+ * SDEV 301: Systems Programming
+ *
+ * @author Kendrick Hang, Tien Han
+ * @version 1.0
+ */
+
+package inventory;
+
+public class LetterPresence {
+    private int inventory;
+
+    public int getIndex(char letter) {
+        //assume letter is valid and lowercase
+        return letter - 'a';
+        //letter a returns 0, letter b returns 1, letter c returns 2
+    }
+
+    public void add(char letter) { //ex: e ||||| f
+        int position = getIndex(letter); //4 ||||| 5
+        int temp = 1 << position; //1 << 4 is bit shift (00000001 becomes 00010000) ||||| 00100000
+        //00000001
+        //00010000 -> shifted 4 places
+        this.inventory += temp; //Add to temp to keep track of all "1"'s
+    }
+
+    public boolean isPresent(char letter) {
+        int position = getIndex(letter);
+        int temp = 1 << position;
+        int check = inventory & temp; //bitwise and
+        //Checking for e
+        //inv  -> 0110000
+        //temp -> 0010000
+        //check-> 0010000 -> this is saying that there is one e
+        //Checking for g
+        //inv  -> 0110000
+        //temp -> 10000000
+        //check-> 00000000
+
+        return check > 0;
+    }
+}

tests/inventory/LetterInventoryTest.java

@@ -6,7 +6,6 @@
 import static org.junit.jupiter.api.Assertions.*;
 
 class LetterInventoryTest {
-/*
     static LetterInventory washington;
     static LetterInventory empty;
     static LetterInventory atoz;
@@ -125,5 +124,4 @@ void isEmpty() {
         assertFalse(atoz.isEmpty());
         assertFalse(washington.isEmpty());
     }
-*/
 }