Comparison and difference between dependence and Association

rely on

Understand and analyze

1. Dependency in uml Dotted lines and arrows are used in the figure to indicate , The class pointed by the arrow indicates that the class is dependent .
2. Dependency embodies a relationship between use and being used , For example, the example in the following example , People can rely on cars while driving , When people don't need to drive, they don't rely on cars .
3. Dependency is uml Among the five relationships , The one with the least coupling
4. The life cycle is very small , After relying on other classes, the relationship between the two classes ends

Three forms ：

1. The dependent class is passed to the dependent class as a method parameter
2. The dependent class is declared and instantiated in the method of the dependent class
3. The dependent class declares a static public method , Dependent classes are called directly in the form of class name point methods in methods .

UML chart

Code implementation

/** * @program: zwbStudy * @description:  automobile  * @author:  Zhaiwenbiao  * @create: 2022-07-21 15:04 **/
public class Car {
    
    public void move(){
    
        System.out.println(" The car moves ");
    }

    public static void speedUp(){
    
        System.out.println(" The car accelerates ");
    }
}


/** * @program: zwbStudy * @description:  people  * @author:  Zhaiwenbiao  * @create: 2022-07-21 15:04 **/
public class Person {
    
    //  The first form of dependency 
    private void drive(Car car){
    
        car.move();
    }

    //  The second form of dependency 
    private void drive(){
    
        Car car = new Car();
        car.move();
    }

    //  The third form of dependency 
    private void drive(String param){
    
        Car.speedUp();
    }
}

relation

Understand and analyze

1. The relation of association is expressed in the form of solid line and arrow , The class pointed by the arrow is the associated class
2. The relationship embodied by association is stronger than dependence
3. relation (Association） A relationship is a join between classes , It lets one class know the properties and methods of another class . Association can be two-way , It could be one-way . stay Java In language , Association is generally realized by member variables .

UML chart

Code implementation

/** * @program: zwbStudy * @description:  Address  * @author:  Zhaiwenbiao  * @create: 2022-07-21 15:10 **/
public class Address {
    
    private String address;

    public String getAddress() {
    
        return address;
    }

    public void setAddress(String address) {
    
        this.address = address;
    }
}

/** * @program: zwbStudy * @description: * @author:  Zhaiwenbiao  * @create: 2022-07-21 15:10 **/
public class Customer {
    
    private Address address;

    //  register 
    private void register(){
    
        address.setAddress(" Anzi District ");
        System.out.println(address.getAddress());
    }
}

The difference between dependency and Association

● From the perspective of coupling
Neither of the two classes that have dependencies adds properties . One class is used as a parameter of another class's method or a variable of a method
Two classes that are associated with each other , One class acts as an attribute of the other class , Attributes are a more tightly coupled relationship , It's a longer-term relationship , Therefore, the coupling of association is stronger than that of dependence
● Compare from the perspective of the declaration cycle of the two relationships
The life cycle of a dependency only exists in the current method that calls the dependent class , After the method ends, the dependency between the two classes ends .
The relationship of association is generated when the class is instantiated , The association relationship ends when the class is destroyed