Detailed introduction to objects in java

1. Creation of objects

Steps:

（ 1) Declaring object variables: The declaration of object variables does not create an object. The system only allocates a reference space for the change.

(2) Instantiation of the object: Allocate space for the object, execute the constructor method after the new operator to complete the initialization of the object, and return a reference to the object.

Process:

1. First allocate memory space for the object and initialize the member variables. The initial value of numeric variables is 0, logical variables are false, and reference variables are null.

2. Perform explicit initialization, that is, execute the simple assignment expression included in the class member declaration.

3. Execute the construction method and initialize the object.

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2. Use of objects

Reference object variables

The state of the object and the methods of the object can be accessed through the origin operator (.)

Format: objectReference.variableName

Access to object variables: setter and getter

Calling the method of the object

Calling the method of the object: objecReference.methodName(argumentList);

Object methods can allow or prohibit other objects to access by setting access permissions

3. Object Clearance

Garbage Collector

The garbage collector periodically releases the memory occupied by objects that are not referenced and automatically performs memory recycling. .

Disadvantages: The collection speed is slow

You can explicitly delete the reference of an object: assign the reference variable value to null

The final value of the object Finalization processing

Before an object is collected, the garbage collector will call the object's finalize() method so that the object itself can do the final cleanup.

inalize() method is a member method of the Object class.

If you want to override the finalize() method, you must call the super.finalize() method before the end of the method, that is, call the finalize() method of the parent class to finalize the inherited resources of the object. .

protected void finalize() throws throwable{
....//当前类对象所需的清理
super.finalize();//调用父类的最终清理方法
}

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