How to create objects in Java? Five ways to introduce

We always talk about creating a new object if there is no object. The way to create an object has become the deep-rooted new method in my case, but in fact there are still many ways to create an object. Yes, not only the new method is used to create objects, but also the reflection mechanism is used to create objects, the clone method is used to create objects, and objects are created through serialization and deserialization. Here is a summary of several ways to create objects, so as to learn how to create objects in Java.

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1. Use the new keyword

This is our most common and simplest way to create objects. In this way we can also call any good function (parameterless and parameterized).

For example: Student student = new Student();

2. Use the newInstance method of the Class class

This newInstance The method calls the constructor without parameters to create the object,

For example: Student student2 = (Student)Class.forName("Root path.Student").newInstance();

Or: Student stu = Student.class.newInstance();

3. Use the newInstance method of the Constructor class

This method is very similar to the newInstance method of the Class class Like, there is also a newInstance method in the java.lang.relect.Constructor class to create objects. We

can call parameterized and private constructors through this newInstance method.

For example: Constructor constructor = Student.class.getInstance(); Student stu = constructor.newInstance();

These two newInstance methods are what everyone calls reflection. In fact, the newInstance method of Class internally calls the newInstance method of Constructor.

This is also the reason why many frameworks such as Spring, Hibernate, Struts, etc. use the latter.

4. Use the clone method

Whenever we call the clone method of an object, the JVM will create a new object and All the contents of the previous object are copied in. Creating an object using the clone method does not call any constructor. To use the clone method, we must first implement the Cloneable interface and implement the clone method it defines.

For example: Student stu2 = stu.clone();

This is also the application of prototype mode.

5. Use deserialization

When we serialize and deserialize an object, the JVM will create a separate object for us. , during deserialization, the JVM creates the object and does not call any constructor. In order to deserialize an object, we need to make our class implement the Serializable interface.

For example: ObjectInputStream in = new ObjectInputStream (new FileInputStream("data.obj")); Student stu3 = (Student)in.readObject();

This article comes from java Getting Started column, welcome to learn!

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