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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：http://www.cnblogs.com/shamgod/p/4585488.html
