zoukankan      html  css  js  c++  java
  • Java-马士兵设计模式学习笔记-策略模式-模拟 Comparator接口

    续上一篇  《Java 模拟 Comparable接口》

    一、Teacher类及Student类的比较大小方式是不固定的,比如老师除了比较职称外,还可比较工龄大小,年龄大小等。则定义Comparator接口,不同比较方法去定义为一个xxComparator类,去实现Comparator接口,Teacher类及Student类引用具体的xxComparator比较器,则可实现灵活的比较方式切换。此则为策略模式的一个例子:当我要比较大小的时候,先定义一个比较器Comparator,但具体的比较由具体的比较策略去实现,如TeacherAgeComparator

    PS:解决的问题一涉及要求灵活多变,可扩展等进,则应重点考虑使用多态思想。

    二、有如下几个类:

    1.DataSorter.java

    2.Studnet.java

    3.Teacher.java

    4.Comparable.java

    5.Comparator.java

    6.TeacherAgeComparator.java

    7.StudentMarkComparaotr.java

    1.DataSorter.java(和上一篇一样)

    public class DataSorter {
    
    	public static void sort(Comparable [] a) {
    		
    		int index;							//保存每次比较,最大值的下标;
    		
    		for(int i = 1; i < a.length; i++){	//控制外循环次数
    			index = 0;
    			for(int j = 1; j <= a.length - i ; j++){
    				if(a[j].compareTo(a[index]) == 1){
    					index = j;
    				}
    			}
    			swap(a, index, a.length -i);
    		}
    	}
    
    
    	private static void swap(Comparable[] a, int x, int y) {
    		Comparable tmp = a[x];
    		a[x] = a[y];
    		a[y] = tmp;
    		
    	}
    	
    	
    	//输出数组元素
    	public static void show(Comparable[] a) {
    		for(int i = 0; i < a.length; i++){
    			System.out.println(a[i]);
    		}
    	}
    
    }
    

      

    2.Studnet.java

    public class Student implements Comparable<Student> {
    
    	private int mark;
    	private Comparator<Student> comparator = new StudentMarkComparator();
    
    	public int getMark() {
    		return mark;
    	}
    
    	public void setMark(int mark) {
    		this.mark = mark;
    	}
    
    	public Student(int mark) {
    		super();
    		this.mark = mark;
    	}
    	
    	@Override
    	public String toString() {
    		return "student" +mark+" ";
    	}
    
    	@Override
    	public int compareTo(Student o) {
    		return comparator.compare(this, o);
    	}
    }
    

      

    3.Teacher.java

    public class Teacher implements Comparable<Teacher> {
    
    	private int title;
    	private int age;
    	private Comparator<Teacher> comparator = new TeacherAgeComparator();
    	
    	public int getAge() {
    		return age;
    	}
    
    	public void setAge(int age) {
    		this.age = age;
    	}
    
    
    	public Teacher(int age) {
    		super();
    		this.age = age;
    	}
    	
    	public int getTitle() {
    		return title;
    	}
    
    	public void setTitle(int title) {
    		this.title = title;
    	}
    
    	@Override
    	public int compareTo(Teacher o) {
    		return comparator.compare(this, o);
    	}
    	
    	@Override
    	public String toString() {
    		return "teacher--" +age+" ";
    	}
    }
    

      

    4.Comparable.java

    public interface Comparable<T> {
    	public int compareTo(T o);
    }
    

      

    5.Comparator.java

    public interface Comparator<T> {
    
    	int compare(T o1, T o2);
    
    }
    

      

    6.TeacherAgeComparator.java

    public class TeacherAgeComparator implements Comparator<Teacher> {
    
    	@Override
    	public int compare(Teacher o1, Teacher o2) {
    		if(o1.getAge() > o2.getAge()){
    			return 1;
    		}else if(o1.getAge() == o2.getAge()){
    			return 0;
    		}else{
    			return -1;
    		}
    	}
    	
    }
    

      

    7.StudentMarkComparaotr.java

    public class StudentMarkComparator implements Comparator<Student> {
    
    	@Override
    	public int compare(Student o1, Student o2) {
    		if(o1.getMark() > o2.getMark())	return 1;
    		else if(o1.getMark() == o2.getMark())	return 0;
    		else	return -1;
    	}
    
    }
    

      

    8.Test.java

    public class Test {
    
    	public static void main(String[] args) {
    		//int [] a = {9,2,1,8,0,3};
    		Student [] ss = {new Student(59),new Student(30),new Student(90)};
    		DataSorter.sort(ss);
    		DataSorter.show(ss);
    		
    		Teacher [] ts = {new Teacher(10),new Teacher(3),new Teacher(12)};
    		DataSorter.sort(ts);
    		DataSorter.show(ts);
    		
    	}
    
    }
    

      

    测试结果

  • 相关阅读:
    Socket通信
    浏览器调用打印机
    python dict操作
    python list操作
    python 模块Example链接
    python random模块
    python configparser模块
    python unittest模块
    python timeit模块
    python datetime模块
  • 原文地址:https://www.cnblogs.com/shamgod/p/4585646.html
Copyright © 2011-2022 走看看