Introduction to Java programming tutorial--class creation process

Construction method

There is a special member method in each Java class, and its method name is consistent with the class         name . When creating an object, call this special method to initialize member variables, this method is called a constructor.

 Notice

The format of creating a constructor method is the same as that of creating a member method, but the following points should be noted:

• 1. The name of the constructor is the same as the class name of the class to which it belongs
• 2. The construction method is to assign an initial value to the object and has no return value
• 3. The construction method cannot be explicitly called by the program, but is automatically called by the system when new constructs the object
• 4. A constructor can have zero or more formal parameters
• 5. The construction method can be defined by the user in the class. If the user does not define it, the system will automatically generate an empty construction method
• 6. The constructor can implement different initialization methods through overloading

The format of the constructor

        The format for creating a constructor is:

        Format 1: No parameter construction method

             access control class name () { constructor body }

        Format 2: Constructor method with parameters

            Access control class name (type 1  parameter 1[, type 2  parameter 2,...] )

            { constructor body }

Example program to initialize object properties using constructor:

package test;

public class Person {
	String name;
	int age;
	
	public Person(String str, int a){
		name = str;
		age = a;
	}
	
	public void say(){
		System.out.println("姓名："+name+",年龄："+age);
	}
}

package test;

public class JavaDemo {
	public static void main(String[] args) {
		Person p1 = new Person("adili",20);
		p1.say();
	}
}