Changing Exception Types Being Thrown

src/main/java/com/williamfiset/algorithms/datastructures/balancedtree/RedBlackTree.java

@@ -146,7 +146,7 @@ public boolean contains(T value) {
 
   public boolean insert(T val) {
     if (val == null) {
-      throw new IllegalArgumentException("Red-Black tree does not allow null values.");
+      throw new NullPointerException("Red-Black tree does not allow null values.");
     }
 
     Node x = root, y = NIL;

src/main/java/com/williamfiset/algorithms/datastructures/balancedtree/TreapTree.java

@@ -93,7 +93,7 @@ public boolean isEmpty() {
 
   public boolean insert(T val, int priority) {
     if (val == null) {
-      throw new IllegalArgumentException("TreapTree does not allow null values");
+      throw new NullPointerException("TreapTree does not allow null values");
     }
     if (!contains(root, val)) {
       root = insert(this.root, val, priority);

src/main/java/com/williamfiset/algorithms/datastructures/binarysearchtree/SplayTree.java

@@ -6,6 +6,7 @@
 
 import com.williamfiset.algorithms.datastructures.utils.TreePrinter;
 import java.util.ArrayList;
+import java.util.Objects;
 import java.util.Scanner;
 
 /**
@@ -30,13 +31,7 @@ public static class BinaryTree<T extends Comparable<T>> implements TreePrinter.P
     private BinaryTree<T> leftChild, rightChild;
 
     public BinaryTree(T data) {
-      if (data == null) {
-        try {
-          throw new Exception("Null data not allowed into tree");
-        } catch (Exception e) {
-          e.printStackTrace();
-        }
-      } else this.data = data;
+      this.data = Objects.requireNonNull(data);
     }
 
     @Override
@@ -67,13 +62,7 @@ public T getData() {
     }
 
     public void setData(T data) {
-      if (data == null) {
-        try {
-          throw new Exception("Null data not allowed into tree");
-        } catch (Exception e) {
-          e.printStackTrace();
-        }
-      } else this.data = data;
+      this.data = Objects.requireNonNull(data);
     }
 
     @Override

src/main/java/com/williamfiset/algorithms/datastructures/dynamicarray/IntArray.java

@@ -22,14 +22,14 @@ public IntArray() {
 
   // Initialize the array with a certain capacity
   public IntArray(int capacity) {
-    if (capacity < 0) throw new IllegalArgumentException("Illegal Capacity: " + capacity);
+    if (capacity < 0) throw new NegativeArraySizeException("Illegal Capacity: " + capacity);
     this.capacity = capacity;
     arr = new int[capacity];
   }
 
   // Given an array make it a dynamic array!
   public IntArray(int[] array) {
-    if (array == null) throw new IllegalArgumentException("Array cannot be null");
+    if (array == null) throw new NullPointerException("Array cannot be null");
     arr = java.util.Arrays.copyOf(array, array.length);
     capacity = len = array.length;
   }

src/main/java/com/williamfiset/algorithms/datastructures/fenwicktree/FenwickTreeRangeQueryPointUpdate.java

@@ -23,7 +23,7 @@ public FenwickTreeRangeQueryPointUpdate(int sz) {
   // does not get used, O(n) construction.
   public FenwickTreeRangeQueryPointUpdate(long[] values) {
 
-    if (values == null) throw new IllegalArgumentException("Values array cannot be null!");
+    if (values == null) throw new NullPointerException("Values array cannot be null!");
 
     N = values.length;
     values[0] = 0L;

src/main/java/com/williamfiset/algorithms/datastructures/fenwicktree/FenwickTreeRangeUpdatePointQuery.java

@@ -22,7 +22,7 @@ public class FenwickTreeRangeUpdatePointQuery {
   // does not get used, O(n) construction.
   public FenwickTreeRangeUpdatePointQuery(long[] values) {
 
-    if (values == null) throw new IllegalArgumentException("Values array cannot be null!");
+    if (values == null) throw new NullPointerException("Values array cannot be null!");
 
     N = values.length;
     values[0] = 0L;

src/main/java/com/williamfiset/algorithms/datastructures/fibonacciheap/FibonacciHeap.java

@@ -71,7 +71,7 @@ private void moveToRoot(FibonacciHeapNode<E> node) {
 
   public boolean add(E e) {
     if (e == null) {
-      throw new IllegalArgumentException(
+      throw new NullPointerException(
           "Null elements not allowed in this FibonacciHeap implementation.");
     }
 

src/main/java/com/williamfiset/algorithms/datastructures/hashtable/DoubleHashingTestObject.java

@@ -6,6 +6,7 @@
  */
 package com.williamfiset.algorithms.datastructures.hashtable;
 
+import java.util.Objects;
 import java.util.Random;
 
 public class DoubleHashingTestObject implements SecondaryHash {
@@ -35,15 +36,13 @@ public DoubleHashingTestObject(int data) {
   }
 
   public DoubleHashingTestObject(int[] data) {
-    if (data == null) throw new IllegalArgumentException("Cannot be null");
-    vectorData = data;
+    vectorData = Objects.requireNonNull(data);
     vectorHash();
     computeHash();
   }
 
   public DoubleHashingTestObject(String data) {
-    if (data == null) throw new IllegalArgumentException("Cannot be null");
-    stringData = data;
+    stringData = Objects.requireNonNull(data);
     stringHash();
     computeHash();
   }

src/main/java/com/williamfiset/algorithms/datastructures/hashtable/HashTableOpenAddressingBase.java

@@ -172,7 +172,7 @@ protected static final int gcd(int a, int b) {
   // Place a key-value pair into the hash-table. If the value already
   // exists inside the hash-table then the value is updated.
   public V insert(K key, V val) {
-    if (key == null) throw new IllegalArgumentException("Null key");
+    if (key == null) throw new NullPointerException("Null key");
     if (usedBuckets >= threshold) resizeTable();
 
     setupProbing(key);
@@ -229,7 +229,7 @@ public V insert(K key, V val) {
 
   // Returns true/false on whether a given key exists within the hash-table
   public boolean hasKey(K key) {
-    if (key == null) throw new IllegalArgumentException("Null key");
+    if (key == null) throw new NullPointerException("Null key");
 
     setupProbing(key);
     final int offset = normalizeIndex(key.hashCode());
@@ -273,7 +273,7 @@ public boolean hasKey(K key) {
   // NOTE: returns null if the value is null AND also returns
   // null if the key does not exists.
   public V get(K key) {
-    if (key == null) throw new IllegalArgumentException("Null key");
+    if (key == null) throw new NullPointerException("Null key");
 
     setupProbing(key);
     final int offset = normalizeIndex(key.hashCode());
@@ -319,7 +319,7 @@ public V get(K key) {
   // NOTE: returns null if the value is null AND also returns
   // null if the key does not exists.
   public V remove(K key) {
-    if (key == null) throw new IllegalArgumentException("Null key");
+    if (key == null) throw new NullPointerException("Null key");
 
     setupProbing(key);
     final int offset = normalizeIndex(key.hashCode());

src/main/java/com/williamfiset/algorithms/datastructures/hashtable/HashTableSeparateChaining.java

@@ -104,7 +104,7 @@ public V add(K key, V value) {
 
   public V insert(K key, V value) {
 
-    if (key == null) throw new IllegalArgumentException("Null key");
+    if (key == null) throw new NullPointerException("Null key");
     Entry<K, V> newEntry = new Entry<>(key, value);
     int bucketIndex = normalizeIndex(newEntry.hash);
     return bucketInsertEntry(bucketIndex, newEntry);

src/main/java/com/williamfiset/algorithms/datastructures/kdtree/GeneralKDTree.java

@@ -185,7 +185,7 @@ private class KDNode<E extends Comparable<E>> {
     private KDNode<E> right;
 
     public KDNode(E[] coords) {
-      if (coords == null) throw new IllegalArgumentException("Error: Null coordinate set passed");
+      if (coords == null) throw new NullPointerException("Error: Null coordinate set passed");
       if (coords.length != k)
         throw new IllegalArgumentException(
             "Error: Expected " + k + "dimensions, but given " + coords.length);

src/main/java/com/williamfiset/algorithms/datastructures/linkedlist/DoublyLinkedList.java

@@ -78,9 +78,9 @@ public void addFirst(T elem) {
   }
 
   // Add an element at a specified index
-  public void addAt(int index, T data) throws Exception {
+  public void addAt(int index, T data) {
     if (index < 0 || index > size) {
-      throw new Exception("Illegal Index");
+      throw new IndexOutOfBoundsException(index);
     }
     if (index == 0) {
       addFirst(data);
@@ -105,20 +105,20 @@ public void addAt(int index, T data) throws Exception {
 
   // Check the value of the first node if it exists, O(1)
   public T peekFirst() {
-    if (isEmpty()) throw new RuntimeException("Empty list");
+    if (isEmpty()) throw new IllegalStateException("Empty list");
     return head.data;
   }
 
   // Check the value of the last node if it exists, O(1)
   public T peekLast() {
-    if (isEmpty()) throw new RuntimeException("Empty list");
+    if (isEmpty()) throw new IllegalStateException("Empty list");
     return tail.data;
   }
 
   // Remove the first value at the head of the linked list, O(1)
   public T removeFirst() {
     // Can't remove data from an empty list
-    if (isEmpty()) throw new RuntimeException("Empty list");
+    if (isEmpty()) throw new IllegalStateException("Empty list");
 
     // Extract the data at the head and move
     // the head pointer forwards one node
@@ -139,7 +139,7 @@ public T removeFirst() {
   // Remove the last value at the tail of the linked list, O(1)
   public T removeLast() {
     // Can't remove data from an empty list
-    if (isEmpty()) throw new RuntimeException("Empty list");
+    if (isEmpty()) throw new IllegalStateException("Empty list");
 
     // Extract the data at the tail and move
     // the tail pointer backwards one node
@@ -185,7 +185,7 @@ private T remove(Node<T> node) {
   public T removeAt(int index) {
     // Make sure the index provided is valid
     if (index < 0 || index >= size) {
-      throw new IllegalArgumentException();
+      throw new IndexOutOfBoundsException(index);
     }
 
     int i;

src/main/java/com/williamfiset/algorithms/datastructures/priorityqueue/BinaryHeap.java

@@ -8,6 +8,7 @@
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
+import java.util.Objects;
 
 public class BinaryHeap<T extends Comparable<T>> {
 
@@ -90,9 +91,7 @@ public boolean contains(T elem) {
   // element must not be null, O(log(n))
   public void add(T elem) {
 
-    if (elem == null) throw new IllegalArgumentException();
-
-    heap.add(elem);
+    heap.add(Objects.requireNonNull(elem));
 
     int indexOfLastElem = size() - 1;
     swim(indexOfLastElem);

src/main/java/com/williamfiset/algorithms/datastructures/priorityqueue/BinaryHeapQuickRemovals.java

@@ -11,6 +11,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 import java.util.TreeSet;
 
@@ -106,9 +107,7 @@ public boolean contains(T elem) {
   // element must not be null, O(log(n))
   public void add(T elem) {
 
-    if (elem == null) throw new IllegalArgumentException();
-
-    heap.add(elem);
+    heap.add(Objects.requireNonNull(elem));
     int indexOfLastElem = size() - 1;
     mapAdd(elem, indexOfLastElem);
 

src/main/java/com/williamfiset/algorithms/datastructures/priorityqueue/MinDHeap.java

@@ -5,6 +5,8 @@
  */
 package com.williamfiset.algorithms.datastructures.priorityqueue;
 
+import java.util.Objects;
+
 @SuppressWarnings("unchecked")
 public class MinDHeap<T extends Comparable<T>> {
 
@@ -61,8 +63,7 @@ public T poll() {
 
   // Adds a none null element to the priority queue
   public void add(T elem) {
-    if (elem == null) throw new IllegalArgumentException("No null elements please :)");
-    heap[sz] = elem;
+    heap[sz] = Objects.requireNonNull(elem);
     swim(sz);
     sz++;
   }

src/main/java/com/williamfiset/algorithms/datastructures/priorityqueue/MinIndexedDHeap.java

@@ -18,6 +18,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.NoSuchElementException;
+import java.util.Objects;
 
 public class MinIndexedDHeap<T extends Comparable<T>> {
 
@@ -104,7 +105,7 @@ public T pollMinValue() {
 
   public void insert(int ki, T value) {
     if (contains(ki)) throw new IllegalArgumentException("index already exists; received: " + ki);
-    valueNotNullOrThrow(value);
+    Objects.requireNonNull(value);
     pm[ki] = sz;
     im[sz] = ki;
     values[ki] = value;
@@ -218,20 +219,15 @@ private void isNotEmptyOrThrow() {
 
   private void keyExistsAndValueNotNullOrThrow(int ki, Object value) {
     keyExistsOrThrow(ki);
-    valueNotNullOrThrow(value);
+    Objects.requireNonNull(value);
   }
 
   private void keyExistsOrThrow(int ki) {
     if (!contains(ki)) throw new NoSuchElementException("Index does not exist; received: " + ki);
   }
 
-  private void valueNotNullOrThrow(Object value) {
-    if (value == null) throw new IllegalArgumentException("value cannot be null");
-  }
-
   private void keyInBoundsOrThrow(int ki) {
-    if (ki < 0 || ki >= N)
-      throw new IllegalArgumentException("Key index out of bounds; received: " + ki);
+    if (ki < 0 || ki >= N) throw new IndexOutOfBoundsException(ki);
   }
 
   /* Test functions */

src/main/java/com/williamfiset/algorithms/datastructures/quadtree/QuadTree.java

@@ -76,8 +76,7 @@ class Node {
 
     // Construct a quad tree for a particular region.
     public Node(Rect region) {
-      if (region == null) throw new IllegalArgumentException("Illegal argument");
-      this.region = region;
+      this.region = Objects.requireNonNull(region);
       X = new long[NUM_POINTS];
       Y = new long[NUM_POINTS];
     }

src/main/java/com/williamfiset/algorithms/datastructures/queue/ArrayQueue.java

@@ -1,5 +1,7 @@
 package com.williamfiset.algorithms.datastructures.queue;
 
+import java.util.NoSuchElementException;
+
 /**
  * Besides the Generics, the loss of property of size is another difference between ArrayQueue and
  * IntQueue. The size of ArrayQueue is calculated by the formula, as are empty status and full
@@ -27,7 +29,7 @@ public ArrayQueue(int capacity) {
   @Override
   public void offer(T elem) {
     if (isFull()) {
-      throw new RuntimeException("Queue is full");
+      throw new IllegalStateException("Queue is full");
     }
     data[rear++] = elem;
     rear = adjustIndex(rear, data.length);
@@ -37,7 +39,7 @@ public void offer(T elem) {
   @SuppressWarnings("unchecked")
   public T poll() {
     if (isEmpty()) {
-      throw new RuntimeException("Queue is empty");
+      throw new NoSuchElementException("Queue is empty");
     }
     front = adjustIndex(front, data.length);
     return (T) data[front++];
@@ -47,7 +49,7 @@ public T poll() {
   @SuppressWarnings("unchecked")
   public T peek() {
     if (isEmpty()) {
-      throw new RuntimeException("Queue is empty");
+      throw new NoSuchElementException("Queue is empty");
     }
     front = adjustIndex(front, data.length);
     return (T) data[front];