排序算法Java(android)安卓中的list对象排序
今天一直在学习排序算法之类的问题,上午正好有机会和大家讨论一下.
由于开发百度舆图获取到的POI信息须要进行由进到远的排序。所以须要些排序算法。
之前是采取冒泡排序算法
算法如下：（摘自网络）
public class MaoPaoSort {
public static void main(String[] args) {
try {
int mp[] = new int[args.length];
for (int i = 0; i < args.length; i++) {
mp[i] = Integer.parseInt(args[i]);
}
for (int i = 0; i < mp.length; i++) {
for (int j = 0; j < mp.length; j++) {
int temp;
if (mp[i] < mp[j]) {
temp = mp[j];
mp[j] = mp[i];
mp[i] = temp;
}
}
}
for (int i = 0; i < mp.length; i++) {
System.out.print(mp[i] + " ");
}
进过搜索发现，本来JAVA工具类已经有排序算法了，遂用之。
Collections类下的sort方法
| static <T> void | sort( List<T> list, Comparator<? super T> comparator)
Sorts the specified list using the specified comparator.
|
| static <T extends Comparable<? super T>> void | sort( List<T> list)
Sorts the specified list in ascending natural order.
|
两种方法都能实现排序。
好了，下面是我们须要排序的对象。
一个用于存放通过百度POI搜索失掉的结果的对象
package com.android.so.model;
import com.baidu.platform.comapi.basestruct.GeoPoint;
public class PoiInfo {
private String name;
private String address;
private boolean detail;
private String uid;
private String telephone;
private GeoPoint pt;
private int distance;
private int ePoiType;
public String getName() {
return name;
}
public String getAddress() {
return address;
}
public String getUid() {
return uid;
}
public String getTelephone() {
return telephone;
}
public GeoPoint getPt() {
return pt;
}
public void setName(String name) {
this.name = name;
}
public void setAddress(String address) {
this.address = address;
}
public void setUid(String uid) {
this.uid = uid;
}
public void setTelephone(String telephone) {
this.telephone = telephone;
}
public void setPt(GeoPoint pt) {
this.pt = pt;
}
public int getePoiType() {
return ePoiType;
}
public void setePoiType(int ePoiType) {
this.ePoiType = ePoiType;
}
public boolean isDetail() {
return detail;
}
public void setDetail(boolean detail) {
this.detail = detail;
}
public int getDistance() {
return distance;
}
public void setDistance(int distance) {
this.distance = distance;
}
}
当初我们须要他按照Distance（距离）来进行升序排序。
这里使用方法：
| static <T> void | sort( List<T> list, Comparator<? super T> comparator)
Sorts the specified list using the specified comparator.
|
我们就须要调用方法：
Collections.sort(poiArrayList, new Comparator<PoiInfo>() {
@Override
public int compare(PoiInfo lhs, PoiInfo rhs) {
return lhs.getDistance() - rhs.getDistance();
}
});
同理如果须要进行降序排序，只须要更改return的结果，如下：
Collections.sort(poiArrayList, new Comparator<PoiInfo>() {
@Override
public int compare(PoiInfo lhs, PoiInfo rhs) {
return rhs.getDistance() - lhs.getDistance();
}
});
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以下是另一种方法
| static <T extends Comparable<? super T>> void | sort( List<T> list)
Sorts the specified list in ascending natural order.
|
这种方法须要对象本身实现Comparable<T>接口。
所以PoiInfo类改为：
package com.android.so.model;
import com.baidu.platform.comapi.basestruct.GeoPoint;
public class PoiInfo implements Comparable<PoiInfo> {
private String name;
private String address;
private boolean detail;
private String uid;
private String telephone;
private GeoPoint pt;
private int distance;
private int ePoiType;
public String getName() {
return name;
}
public String getAddress() {
return address;
}
public String getUid() {
return uid;
}
public String getTelephone() {
return telephone;
}
public GeoPoint getPt() {
return pt;
}
public void setName(String name) {
this.name = name;
}
public void setAddress(String address) {
this.address = address;
}
public void setUid(String uid) {
this.uid = uid;
}
public void setTelephone(String telephone) {
this.telephone = telephone;
}
public void setPt(GeoPoint pt) {
this.pt = pt;
}
public int getePoiType() {
return ePoiType;
}
public void setePoiType(int ePoiType) {
this.ePoiType = ePoiType;
}
public boolean isDetail() {
return detail;
}
public void setDetail(boolean detail) {
this.detail = detail;
}
public int getDistance() {
return distance;
}
public void setDistance(int distance) {
this.distance = distance;
}
@Override
public int compareTo(PoiInfo another) {
return getDistance() - another.getDistance();
}
}
实现了compareTo方法，以上是升序排序，如果须要降序排序，将return getDistance() - another.getDistance();改为return another.getDistance() - getDistance();即可。
OK ，那么我们就须要调用代码：
Collections.sort(poiArrayList);
来对list进行排序
OK 上两张对比图
未整理之前：
整理之后的距离：
文章结束给大家分享下程序员的一些笑话语录： 那是习惯决定的，一直保持一个习惯是不好的！IE6的用户不习惯多标签，但是最终肯定还是得转到多标签的浏览器。历史（软件UI）的进步（改善）不是以个人意志（习惯）为转移的！