java排序comparable 与 comparator实例
自定义（复杂）类型，如果遇到按照不同的规则进行排序，可以参照以下的方法。
参考资料：http://z-jianwen.iteye.com/blog/616316
在此，举一例：
package com;
public class Goods {
// 定义全参构造器
public Goods(int _num,int _weigth,int _value){
this.setNum(_num);
this.setValue(_value);
this.setWeigth(_weigth);
}
// 定义方法，获得单位价值
public int getPervalue(){
int perValue = this.value/this.weigth;
return perValue;
}
@Override
public String toString() {
return "Goods[" + this.getNum() + "] : weight = " + this.getWeigth() + " value = " + this.getValue();
}
public int getNum() {
return num;
}
public void setNum(int num) {
this.num = num;
}
public int getWeigth() {
return weigth;
}
public void setWeigth(int weigth) {
this.weigth = weigth;
}
public int getValue() {
return value;
}
public void setValue(int value) {
this.value = value;
}
// 属性
private int num;
private int weigth;
private int value;
}
package comparator;
import java.util.Comparator;
import com.Goods;
public class PerValueComparator implements Comparator<Goods> {
@Override
public int compare(Goods o1, Goods o2) {
// 单位价值大的排前面
if (o1.getPervalue() != o2.getPervalue()) {
return o2.getPervalue() - o1.getPervalue();
}else {
// 如果两者的单位价值相等，则重量小的排前面
return o1.getWeigth() - o2.getWeigth();
}
}
}
package comparator;
import java.util.Comparator;
import com.Goods;
public class ValueComparator implements Comparator<Goods> {
@Override
public int compare(Goods o1, Goods o2) {
// 价值大的排前面
if (o1.getValue() != o2.getValue()) {
return o2.getValue() - o1.getValue();
}else {
// 如果两者的价值相等，则重量小的排前面
return o1.getWeigth() - o2.getWeigth();
}
}
}
package comparator;
import java.util.Comparator;
import com.Goods;
public class WeightComparator implements Comparator<Goods> {
@Override
public int compare(Goods o1, Goods o2) {
// 重量小的排前面
if (o1.getWeigth() != o2.getWeigth()) {
return o1.getWeigth() - o2.getWeigth();
}else {
// 如果两者的重量相等，则价值大的排前面
return o2.getValue() - o1.getValue();
}
}
}
package test;
import java.util.ArrayList;
import java.util.Collections;
import com.Goods;
import comparator.PerValueComparator;
import comparator.ValueComparator;
import comparator.WeightComparator;
public class TestCompare {
public static void main(String[] args) {
ArrayList<Goods> list = new ArrayList<Goods>();
list.add(new Goods(1,20,30));
list.add(new Goods(2,8,10));
list.add(new Goods(3,10,15));
list.add(new Goods(4,30,35));
list.add(new Goods(5,5,8));
list.add(new Goods(6,30,45));
list.add(new Goods(7,18,10));
list.add(new Goods(8,4,5));
System.out.println("---------- before sort ----------");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
// 根据重量从小到大排列
Collections.sort(list, new WeightComparator());
System.out.println("---------- 根据重量从小到大排列 ----------");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
// 根据价值从大到小排列
Collections.sort(list, new ValueComparator());
System.out.println("---------- 根据价值从大到小排列 ----------");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
// 根据单位价值从大到小排列
Collections.sort(list, new PerValueComparator());
System.out.println("---------- 根据单位价值从大到小排列 ----------");
for (int i = 0; i < list.size(); i++) {
System.out.println(list.get(i));
}
}
}
---------- before sort ---------- Goods[1] : weight = 20 value = 30 Goods[2] : weight = 8 value = 10 Goods[3] : weight = 10 value = 15 Goods[4] : weight = 30 value = 35 Goods[5] : weight = 5 value = 8 Goods[6] : weight = 30 value = 45 Goods[7] : weight = 18 value = 10 Goods[8] : weight = 4 value = 5 ---------- 根据重量从小到大排列 ---------- Goods[8] : weight = 4 value = 5 Goods[5] : weight = 5 value = 8 Goods[2] : weight = 8 value = 10 Goods[3] : weight = 10 value = 15 Goods[7] : weight = 18 value = 10 Goods[1] : weight = 20 value = 30 Goods[6] : weight = 30 value = 45 Goods[4] : weight = 30 value = 35 ---------- 根据价值从大到小排列 ---------- Goods[6] : weight = 30 value = 45 Goods[4] : weight = 30 value = 35 Goods[1] : weight = 20 value = 30 Goods[3] : weight = 10 value = 15 Goods[2] : weight = 8 value = 10 Goods[7] : weight = 18 value = 10 Goods[5] : weight = 5 value = 8 Goods[8] : weight = 4 value = 5 ---------- 根据单位价值从大到小排列 ---------- Goods[8] : weight = 4 value = 5 Goods[5] : weight = 5 value = 8 Goods[2] : weight = 8 value = 10 Goods[3] : weight = 10 value = 15 Goods[1] : weight = 20 value = 30 Goods[6] : weight = 30 value = 45 Goods[4] : weight = 30 value = 35 Goods[7] : weight = 18 value = 10