Package Summary Overview Summary

### class:Objects [NONE]
-                                                                                     public final class Objects
      extends Object
This class consists of `static` utility methods for operating on objects, or checking certain conditions before operation. These utilities include `null`-safe or `null`-tolerant methods for computing the hash code of an object, returning a string for an object, comparing two objects, and checking if indexes or sub-range values are out-of-bounds. API Note: Static methods such as `checkIndex(int, int)` , `checkFromToIndex(int, int, int)` , and `checkFromIndexSize(int, int, int)` are provided for the convenience of checking if values corresponding to indexes and sub-ranges are out-of-bounds. Variations of these static methods support customization of the runtime exception, and corresponding exception detail message, that is thrown when values are out-of-bounds. Such methods accept a functional interface argument, instances of `BiFunction`, that maps out-of-bound values to a runtime exception. Care should be taken when using such methods in combination with an argument that is a lambda expression, method reference or class that capture values. In such cases the cost of capture, related to functional interface allocation, may exceed the cost of checking bounds. Since: 1.7

### method:equals(java.lang.Object,java.lang.Object) [NONE]
- #### equals
                                                                                                      public static boolean equals​(Object a,
                                   Object b)
Returns `true` if the arguments are equal to each other and `false` otherwise. Consequently, if both arguments are `null`, `true` is returned and if exactly one argument is `null`, `false` is returned. Otherwise, equality is determined by using the `equals` method of the first argument. Parameters: `a` - an object `b` - an object to be compared with `a` for equality Returns: `true` if the arguments are equal to each other and `false` otherwise See Also: `Object.equals(Object)`

### method:deepEquals(java.lang.Object,java.lang.Object) [NONE]
- #### deepEquals
                                                                                                      public static boolean deepEquals​(Object a,
                                       Object b)
Returns `true` if the arguments are deeply equal to each other and `false` otherwise. Two `null` values are deeply equal. If both arguments are arrays, the algorithm in `Arrays.deepEquals` is used to determine equality. Otherwise, equality is determined by using the `equals` method of the first argument. Parameters: `a` - an object `b` - an object to be compared with `a` for deep equality Returns: `true` if the arguments are deeply equal to each other and `false` otherwise See Also: `Arrays.deepEquals(Object[], Object[])` , `equals(Object, Object)`

### method:hashCode(java.lang.Object) [NONE]
- #### hashCode
                                                                                                      public static int hashCode​(Object o)
Returns the hash code of a non-`null` argument and 0 for a `null` argument. Parameters: `o` - an object Returns: the hash code of a non-`null` argument and 0 for a `null` argument See Also: `Object.hashCode()`

### method:hash(java.lang.Object...) [NONE]
- #### hash
                                                                                                      public static int hash​(Object... values)
  > Generates a hash code for a sequence of input values. The hash code is generated as if all the input values were placed into an array, and that array were hashed by calling `Arrays.hashCode(Object[])`. This method is useful for implementing `Object.hashCode()` on objects containing multiple fields. For example, if an object that has three fields, `x`, `y` , and `z`, one could write:
  >      @Override public int hashCode() {
  >          return Objects.hash(x, y, z);
  >      }
Warning: When a single object reference is supplied, the returned value does not equal the hash code of that object reference. This value can be computed by calling `hashCode(Object)`. Parameters: `values` - the values to be hashed Returns: a hash value of the sequence of input values See Also: `Arrays.hashCode(Object[])`, `List.hashCode()`

### method:toString(java.lang.Object) [NONE]
- #### toString
                                                                                                      public static String toString​(Object o)
Returns the result of calling `toString` for a non-`null` argument and `"null"` for a `null` argument. Parameters: `o` - an object Returns: the result of calling `toString` for a non-`null` argument and `"null"` for a `null` argument See Also: `Object.toString()`, `String.valueOf(Object)`

### method:toString(java.lang.Object,java.lang.String) [NONE]
- #### toString
                                                                                                      public static String toString​(Object o,
                                    String nullDefault)
Returns the result of calling `toString` on the first argument if the first argument is not `null` and returns the second argument otherwise. Parameters: `o` - an object `nullDefault` - string to return if the first argument is `null` Returns: the result of calling `toString` on the first argument if it is not `null` and the second argument otherwise. See Also: `toString(Object)`

### method:compare(T,T,java.util.Comparator) [NONE]
- #### compare
                                                                                                      public static <T> int compare​(T a,
                                    T b,
                                    Comparator<? super T> c)
Returns 0 if the arguments are identical and `c.compare(a, b)` otherwise. Consequently, if both arguments are `null` 0 is returned. Note that if one of the arguments is `null`, a `NullPointerException` may or may not be thrown depending on what ordering policy, if any, the `Comparator` chooses to have for `null` values. Type Parameters: `T` - the type of the objects being compared Parameters: `a` - an object `b` - an object to be compared with `a` `c` - the `Comparator` to compare the first two arguments Returns: 0 if the arguments are identical and `c.compare(a, b)` otherwise. See Also: `Comparable`, `Comparator`

### method:requireNonNull(T) [NONE]
- #### requireNonNull
      public static <T> T requireNonNull​(T obj)
  > Checks that the specified object reference is not `null`. This method is designed primarily for doing parameter validation in methods and constructors, as demonstrated below:
  >      public Foo(Bar bar) {
  >          this.bar = Objects.requireNonNull(bar);
  >      }
Type Parameters: `T` - the type of the reference Parameters: `obj` - the object reference to check for nullity Returns: `obj` if not `null` Throws: `NullPointerException` - if `obj` is `null`

### method:requireNonNull(T,java.lang.String) [NONE]
- #### requireNonNull
                                                                                                      public static <T> T requireNonNull​(T obj,
                                         String message)
  > Checks that the specified object reference is not `null` and throws a customized `NullPointerException` if it is. This method is designed primarily for doing parameter validation in methods and constructors with multiple parameters, as demonstrated below:
  >      public Foo(Bar bar, Baz baz) {
  >          this.bar = Objects.requireNonNull(bar, "bar must not be null");
  >          this.baz = Objects.requireNonNull(baz, "baz must not be null");
  >      }
Type Parameters: `T` - the type of the reference Parameters: `obj` - the object reference to check for nullity `message` - detail message to be used in the event that a `NullPointerException` is thrown Returns: `obj` if not `null` Throws: `NullPointerException` - if `obj` is `null`

### method:isNull(java.lang.Object) [NONE]
- #### isNull
                                                                                                      public static boolean isNull​(Object obj)
Returns `true` if the provided reference is `null` otherwise returns `false`. API Note: This method exists to be used as a `Predicate`, `filter(Objects::isNull)` Parameters: `obj` - a reference to be checked against `null` Returns: `true` if the provided reference is `null` otherwise `false` Since: 1.8 See Also: `Predicate`

### method:nonNull(java.lang.Object) [NONE]
- #### nonNull
                                                                                                      public static boolean nonNull​(Object obj)
Returns `true` if the provided reference is non-`null` otherwise returns `false`. API Note: This method exists to be used as a `Predicate`, `filter(Objects::nonNull)` Parameters: `obj` - a reference to be checked against `null` Returns: `true` if the provided reference is non-`null` otherwise `false` Since: 1.8 See Also: `Predicate`

### method:requireNonNullElse(T,T) [NONE]
- #### requireNonNullElse
      public static <T> T requireNonNullElse​(T obj,
                                             T defaultObj)
Returns the first argument if it is non-`null` and otherwise returns the non-`null` second argument. Type Parameters: `T` - the type of the reference Parameters: `obj` - an object `defaultObj` - a non-`null` object to return if the first argument is `null` Returns: the first argument if it is non-`null` and otherwise the second argument if it is non-`null` Throws: `NullPointerException` - if both `obj` is null and `defaultObj` is `null` Since: 9

### method:requireNonNullElseGet(T,java.util.function.Supplier) [NONE]
- #### requireNonNullElseGet
                                                                                                      public static <T> T requireNonNullElseGet​(T obj,
                                                Supplier<? extends T> supplier)
Returns the first argument if it is non-`null` and otherwise returns the non-`null` value of `supplier.get()`. Type Parameters: `T` - the type of the first argument and return type Parameters: `obj` - an object `supplier` - of a non-`null` object to return if the first argument is `null` Returns: the first argument if it is non-`null` and otherwise the value from `supplier.get()` if it is non-`null` Throws: `NullPointerException` - if both `obj` is null and either the `supplier` is `null` or the `supplier.get()` value is `null` Since: 9

### method:requireNonNull(T,java.util.function.Supplier) [NONE]
- #### requireNonNull
                                                                                                      public static <T> T requireNonNull​(T obj,
                                         Supplier<String> messageSupplier)
Checks that the specified object reference is not `null` and throws a customized `NullPointerException` if it is. Unlike the method `requireNonNull(Object, String)` , this method allows creation of the message to be deferred until after the null check is made. While this may confer a performance advantage in the non-null case, when deciding to call this method care should be taken that the costs of creating the message supplier are less than the cost of just creating the string message directly. Type Parameters: `T` - the type of the reference Parameters: `obj` - the object reference to check for nullity `messageSupplier` - supplier of the detail message to be used in the event that a `NullPointerException` is thrown Returns: `obj` if not `null` Throws: `NullPointerException` - if `obj` is `null` Since: 1.8

### method:checkIndex(int,int) [NONE]
- #### checkIndex
      public static int checkIndex​(int index,
                                   int length)
Checks if the `index` is within the bounds of the range from `0` (inclusive) to `length` (exclusive). The `index` is defined to be out-of-bounds if any of the following inequalities is true: `index < 0` `index >= length` `length < 0` , which is implied from the former inequalities Parameters: `index` - the index `length` - the upper-bound (exclusive) of the range Returns: `index` if it is within bounds of the range Throws: `IndexOutOfBoundsException` - if the `index` is out-of-bounds Since: 9

### method:checkFromToIndex(int,int,int) [NONE]
- #### checkFromToIndex
      public static int checkFromToIndex​(int fromIndex,
                                         int toIndex,
                                         int length)
Checks if the sub-range from `fromIndex` (inclusive) to `toIndex` (exclusive) is within the bounds of range from `0` (inclusive) to `length` (exclusive). The sub-range is defined to be out-of-bounds if any of the following inequalities is true: `fromIndex < 0` `fromIndex > toIndex` `toIndex > length` `length < 0` , which is implied from the former inequalities Parameters: `fromIndex` - the lower-bound (inclusive) of the sub-range `toIndex` - the upper-bound (exclusive) of the sub-range `length` - the upper-bound (exclusive) the range Returns: `fromIndex` if the sub-range within bounds of the range Throws: `IndexOutOfBoundsException` - if the sub-range is out-of-bounds Since: 9

### method:checkFromIndexSize(int,int,int) [NONE]
- #### checkFromIndexSize
      public static int checkFromIndexSize​(int fromIndex,
                                           int size,
                                           int length)
Checks if the sub-range from `fromIndex` (inclusive) to `fromIndex + size` (exclusive) is within the bounds of range from `0` (inclusive) to `length` (exclusive). The sub-range is defined to be out-of-bounds if any of the following inequalities is true: `fromIndex < 0` `size < 0` `fromIndex + size > length` , taking into account integer overflow `length < 0` , which is implied from the former inequalities Parameters: `fromIndex` - the lower-bound (inclusive) of the sub-interval `size` - the size of the sub-range `length` - the upper-bound (exclusive) of the range Returns: `fromIndex` if the sub-range within bounds of the range Throws: `IndexOutOfBoundsException` - if the sub-range is out-of-bounds Since: 9