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Chapter 3. GENERICS AND COLLECTIONS (Working with Generics (CANNOT do with…

- - - - Static methods
        
        Consumer<List<Integer>> methodRef1 = Collection::sort;
      - Instance methods on a particular instance
        
        Predicate<String> methodRef2 = str::startsWith;
      - Instance methods on an instance to be determined at runtime
        
        Predicate<String> methodRef3 = String::isEmpty;
      - Constructors
        
        Supplier<ArrayList> methodRef4 = ArrayList::new;
  - - - Use BiFunction
      - [Key in map] Result of function
      - [Key not in map] Add new value to map
    - - Use BiFunction
      - [Key in map] Result of function
      - [Key not in map] No action
    - - Use Function
      - [Key in map] No action
      - [Key not in map] Result of function
- - - - Formal type parameter in angle brackets
    - - E for an element
      - K for a map key
      - V for a map value
      - N for a number
      - T for a generic data type
      - S,U,V and so forth for multiple generic types
    - - Remove the generics syntax from your code is referred (and replace with Object)
      - Allow your code to be compatible with older version of Java
      - The compiler adds the relevant casts for your code to work with his type of erased class
  - - - Specific the generic type in the class
      - Create a generic class
      - Not use generics at all
  - - - Unbounded wildcard <?>
      - Wildcard with an upper bound <? extends type>
      - Wildcard with a lower bound <? super type>
- - - - HashSet
        
        Store elements in a hash table
        
        Add elements + check an element exist both have constant time
        
        Lose the order
      - TreeSet
        
        Store elements in a sorted tree structure
        
        Add + Check an element exist both O(log n)
        
        Implement NavigableSet interface
        
        E lower(E e)
        
        Return greatest element < e || null if no exist
        
        E higher(E e)
        
        Return smallest element > e || null if no exist
        
        E floor(E e)
        
        Return greatest element <= e || null if no exist
        
        E ceiling(E e)
        
        Return smallest element >= e || null if no exist
  - - - LinkedList
        
        List + Double-ended queue
      - ArrayDeque
        
        "Pure" double-ended queue
        
        Methods
        
        Gets
        
        E element()
        
        Return the next element
        
        Throws an exception if empty queue
        
        E peek() (*)
        
        Return the next element
        
        Return null if empty queue
        
        Removes
        
        E remove()
        
        Throw an exception if empty queue
        
        For queue
        
        E poll() (*)
        
        Return null if empty queue
        
        For queue
        
        E pop()
        
        Throw an exception if empty queue
        
        For stack
        
        Adds
        
        void push(E e)
        
        Add to the front
        
        boolean offer(E e) (*)
        
        Add to the back
        
        Return whether successful
        
        boolean add(E e)
        
        Add to the back
        
        Return true or throws an exception
  - - - LinkedList
        
        Implement both List and Queue
        
        Additional methods to facilitate add/remove from begin/end of the list
      - ArrayList
        
        resizable array
        
        Look up any element in constant time
        
        Adding/Removing time > Accessing time
      - Old implementations
        
        Vector
        
        Stack
  - - - HashMap
        
        Store keys in a hash table
      - TreeMap
        
        Store key in a sorted tree structure
      - Hashtable
    - - int size()
      - V get(Object key)
      - boolean isEmpty()
      - V put(K key, V value)
      - void clear()
      - V remove(Object key)
      - boolean containsKey(Object key)
      - boolean containsValue(Object value)
      - Set<K> keySet()
      - Collection<V> values()
  - - - TreeMap
      - TreeSet
      - HashTable
      - ArrayDeque
- - - - 0 when the current object is equal to the argument
      - < 0 when the current object is smaller than the argument
      - 0 when the current object is larger than the argument
    - - If and only if x.equals(y) is true whenever x.compareTo(y) equals(0)