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Object Class

Supports all classes in the .NET Framework class hierarchy and provides low-level services to derived classes. This is the ultimate base class of all classes in the .NET Framework; it is the root of the type hierarchy.

Namespace: System
Assembly: mscorlib (in mscorlib.dll)

'Declaration
<SerializableAttribute> _
<ComVisibleAttribute(True)> _
<ClassInterfaceAttribute(ClassInterfaceType.AutoDual)> _
Public Class Object
'Usage
Dim instance As Object

/** @attribute SerializableAttribute() */ 
/** @attribute ComVisibleAttribute(true) */ 
/** @attribute ClassInterfaceAttribute(ClassInterfaceType.AutoDual) */ 
public class Object
SerializableAttribute 
ComVisibleAttribute(true) 
ClassInterfaceAttribute(ClassInterfaceType.AutoDual) 
public class Object

Languages typically do not require a class to declare inheritance from Object because the inheritance is implicit.

Because all classes in the .NET Framework are derived from Object, every method defined in the Object class is available in all objects in the system. Derived classes can and do override some of these methods, including:

  • Equals - Supports comparisons between objects.

  • Finalize - Performs cleanup operations before an object is automatically reclaimed.

  • GetHashCode - Generates a number corresponding to the value of the object to support the use of a hash table.

  • ToString - Manufactures a human-readable text string that describes an instance of the class.

Performance Considerations

If you are designing a class, such as a collection, that must handle any type of object, you can create class members that accept instances of the Object class. However, the process of boxing and unboxing a type carries a performance cost. If you know your new class will frequently handle certain value types you can use one of two tactics to minimize the cost of boxing.

One tactic is to create a general method that accepts an Object type, and a set of type-specific method overloads that accept each value type you expect your class to frequently handle. If a type-specific method exists that accepts the calling parameter type, no boxing occurs and the type-specific method is invoked. If there is no method argument that matches the calling parameter type, the parameter is boxed and the general method is invoked. This tactic yields methods that are CLS-compliant.

The other tactic is to design your class and its methods to use generics. The common language runtime creates a closed generic type when you create an instance of your class and specify a generic type argument. The generic method is type-specific and can be invoked without boxing the calling parameter. This tactic yields methods that are not CLS-compliant in the .NET Framework version 2.0.

The following example defines a Point type derived from the Object class and overrides many of the virtual methods of the Object class. In addition, the example shows how to call many of the static and instance methods of the Object class.

No code example is currently available or this language may not be supported.

Public static (Shared in Visual Basic) members of this type are safe for multithreaded operations. Instance members are not guaranteed to be thread-safe.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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