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  • Java-马士兵设计模式学习笔记-策略模式-模拟Comparable接口

    一、情况

    1.目标:要在专门用于排序数据的DataSorter.java中实现对所有A类,B类,C类,D类等等的排序

    2.初步想法:DataSorter.java的代码如下

    public class DataSorter {
    
    	public static void sort(A a){
    		
    	}
    	
    	public static void sort(B a){
    		
    	}
    	
    	public static void sort(C c){
    		
    	}
    	
    	//...................
    }
    

      

    3.这样会造成DataSorter的可扩展性差,要支持对新类的排序时,要修改代码。更好的思路是:既然DataSorter是要根据不同的类的采取不同的方法实现排序,那么具体实现排序的方法交由子类去实现,且都实现同一个接口Comparable,那么DataSorter只需对Comparable排序,而无需理会具体要排序的是什么类(多态)

    4.有如下几个类:

    (1)DataSorter.java

    (2)接口Comparable.java

    (3)Student.java

    (4)Teacher.java

    (5)Test.java

    5.代码如下:

    (1)DataSorter.java

    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)Comparable.java

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

      

    (3)Teacher.java

    public class Teacher implements Comparable<Teacher> {
    
    	private int title;
    	
    	public Teacher(int title) {
    		super();
    		this.title = title;
    	}
    
    	public int getTitle() {
    		return title;
    	}
    
    	public void setTitle(int title) {
    		this.title = title;
    	}
    
    	@Override
    	public int compareTo(Teacher o) {
    		if(this.title > o.getTitle()){
    			return 1;
    		}else if(this.title == o.getTitle()){
    			return 0;
    		}else{
    			return -1;
    		}
    	}
    	
    	@Override
    	public String toString() {
    		return "teacher--" +title+" ";
    	}
    }
    

      

    (4)Student.java

    public class Student implements Comparable<Student> {
    
    	private int mark;
    
    	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) {
    		if(this.mark > o.getMark()){
    			return 1;
    		}else if(this.mark == o.getMark()){
    			return 0;
    		}else{
    			return -1;
    		}
    	}
    }
    

      

    (5)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

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  • 原文地址:https://www.cnblogs.com/shamgod/p/4585488.html
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