The use of java-method and construction method

The Declaration form and function of the method

Return value data type method name (formal parameter list)

{

Execute the statement;

return value;

}

---method is the behavior of an object

---method is to define a separate applet that has a specific function in the class

---method is also called a function.

Method overloading

--in Java, if you have multiple methods with the same name but different parameters, it becomes the overloaded method

Three main principles of method overloading

-Method name is the same

-Different parameters (can be different in three ways)

--Different quantity

--Different types

--Different order

-Same scope

Only methods that have different return values do not form overloads

Instance:

public class Overloadtest {

Define a method to add a two integer

public void Add (int a,int b) {

int sum = a+b;

System.out.println ("The sum of two integers is:" + (a+b));

}

Define a method to add a three integer

public int Add (int a,int b,int c) {

return a+b+c;

}

Define a method to add two floating-point numbers

Protected double Add (double a,double b) {

return a+b;

}

Define a method to add an integer number and a decimal

void Add (int a,double b) {

Double sum = a+b;

System.out.println ("The sum of two integers is:" +sum);

}

Declaration form and function of construction method

Constructor method: Used to instantiate a class, that is, to create an object.

Composition of the construction method

Access permission modifier class name (formal argument list) {method body}

--Called when the object is instantiated.

-No return value, not even void

--the method name must be the same as the class name

--cannot use modifiers, including static, final, abstract

Java object creation and use

--Call a constructor without parameters

Class Name Object name = new constructor method for this class ();

Example: Book Javabook = new book ();

--Call the constructor method with parameters

Class Name Object name = new constructor method for this class (parameter 1, parameter 2 ...);

Example: Book Javabook = new book (1, "Journey to the Monkey");

Working with objects: using "." Do the following

---Access the properties of the class: Object name. Properties

---method of calling the class: Object name. Method Name ()

The use of java-method and construction method