Objects (Dracula Javadoc Sample)

java.lang.Object
- java.util.Objects

```
public final class Objects
extends Object
```
This class consists of static utility methods for operating on objects. These utilities include null-safe or null-tolerant methods for computing the hash code of an object, returning a string for an object, and comparing two objects.

Since:

1.7

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`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.
`static boolean`	`deepEquals(Object a, Object b)` Returns `true` if the arguments are deeply equal to each other and `false` otherwise.
`static boolean`	`equals(Object a, Object b)` Returns `true` if the arguments are equal to each other and `false` otherwise.
`static int`	`hash(Object... values)` Generates a hash code for a sequence of input values.
`static int`	`hashCode(Object o)` Returns the hash code of a non-`null` argument and 0 for a `null` argument.
`static boolean`	`isNull(Object obj)` Returns `true` if the provided reference is `null` otherwise returns `false`.
`static boolean`	`nonNull(Object obj)` Returns `true` if the provided reference is non-`null` otherwise returns `false`.
`static <T> T`	`requireNonNull(T obj)` Checks that the specified object reference is not `null`.
`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.
`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.
`static String`	`toString(Object o)` Returns the result of calling `toString` for a non-`null` argument and `"null"` for a `null` argument.
`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.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - 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)
  - 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)
  - 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()
  - 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()
  - 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)
  - 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)
  - 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
  - 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
  - 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
  - isNull
```
public static boolean isNull(Object obj)
```
    Returns true if the provided reference is null otherwise returns false.
    
    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
  - nonNull
```
public static boolean nonNull(Object obj)
```
    Returns true if the provided reference is non-null otherwise returns false.
    
    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
  - 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

Class Objects

Method Summary

Methods inherited from class java.lang.Object

Method Detail

equals

deepEquals

hashCode

hash

toString

toString

compare

requireNonNull

requireNonNull

isNull

nonNull

requireNonNull