设计模式_05_迪米特原则

迪米特原则

定义：一个对象应该对其他对象保持最少的了解。又叫最少知道原则
尽量降低类与类之间的耦合
优点：降低类之间的耦合

public class Course {

}

public class TeamLeader {
    public void checkNumOfCourses(List<Course> courses) {
        System.out.println("course num is " + courses.size());
    }
}

public class Boss {
    public void countCheck(TeamLeader teamLeader) {
        ArrayList<Course> courses = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            courses.add(new Course());
        }
        teamLeader.checkNumOfCourses(courses);
    }
}

public class Test {

    public static void main(String[] args) {
        Boss boss = new Boss();
        TeamLeader teamLeader = new TeamLeader();
        boss.countCheck(teamLeader);

    }
}

类图：
设计模式_05_迪米特原则
更改之后：

public class Boss {
    public void countCheck(TeamLeader teamLeader) {

        teamLeader.checkNumOfCourses();
    }
}

public class TeamLeader {
    public void checkNumOfCourses() {
        ArrayList<Course> courses = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            courses.add(new Course());
        }
        System.out.println("course num is " + courses.size());
    }
}

类图：
设计模式_05_迪米特原则
源码地址