What does java instantiation look like?

What is instantiation in java                                                                                                                                                                                         # The action of the statement is called creating an object, that is, instantiation. In fact, it contains four actions.

1) The "new Demo" on the right uses the Demo class as a template to create a Demo class object (also referred to as the Demo object) in the heap space.

2) The () at the end means that after the object is created, the constructor of the Demo class is called immediately to initialize the newly generated object. There is definitely a constructor. If you don't write it, Java will add a default constructor for you.

3) The "Demo demo" on the left creates a Demo class reference variable. The so-called Demo class reference is an object reference that can be used to point to the Demo object in the future.

4) The "=" operator makes the object reference point to the Demo object just created.

Five ways to create (instantiate) objects in Java

1. Use the new statement to create an object. This is the most common way to create an object.

2. Return the object through the factory method, such as:

Demo demo = new Demo();

3. Use reflection to call the newInstance() instance method of the java.lang.Class or java.lang.reflect.Constructor class . For example:

String str = String.valueOf(23);

4. Call the clone() method of the object.

5. Through the I/O stream (including deserialization), such as using deserialization means, call the readObject() method of the java.io.ObjectInputStream object.

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