Java:如何对自定义类型ArrayList排序
我有一个自定义类型Java:如何对自定义类型ArrayList排序,java,collections,arraylist,quicksort,mergesort,Java,Collections,Arraylist,Quicksort,Mergesort,我有一个自定义类型Position(x,y,z),现在我创建了一个ArrayList,我想按z值排序这个数组,从小到大,如何使用集合进行排序。排序或者有其他有效的排序方法吗 当我尝试使用 public class PositionComparator implements Comparator<Position> { @Override public int compare(Position o1, Position o2) {
Position(x,y,z)
,现在我创建了一个ArrayList
,我想按z值排序这个数组,从小到大,如何使用集合进行排序。排序
或者有其他有效的排序方法吗
当我尝试使用
public class PositionComparator implements Comparator<Position> {
@Override
public int compare(Position o1, Position o2) {
// TODO Auto-generated method stub
return o1.height().compareTo(o2.height());
}
}
您需要实现
比较器,它将比较z
属性的值。试试看
Collections.sort(SortList, new Comparator<Position>(){
public int compare(Position p1, Position p2) {
return p1.z- p2.z;
}
});
Collections.sort(SortList,newcomparator(){
公共整数比较(位置p1,位置p2){
返回p1.z-p2.z;
}
});
比如说
class User {
String name;
String age;
public User(String name, String age) {
this.name = name;
this.age = age;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
import java.util.Comparator;
public class ComparatorUser implements Comparator {
public int compare(Object arg0, Object arg1) {
User user0 = (User) arg0;
User user1 = (User) arg1;
int flag = user0.getAge().compareTo(user1.getAge());
if (flag == 0) {
return user0.getName().compareTo(user1.getName());
} else {
return flag;
}
}
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class SortTest {
public static void main(String[] args) {
List userlist = new ArrayList();
userlist.add(new User("dd", "4"));
userlist.add(new User("aa", "1"));
userlist.add(new User("ee", "5"));
userlist.add(new User("bb", "2"));
userlist.add(new User("ff", "5"));
userlist.add(new User("cc", "3"));
userlist.add(new User("gg", "6"));
ComparatorUser comparator = new ComparatorUser();
Collections.sort(userlist, comparator);
for (int i = 0; i < userlist.size(); i++) {
User user_temp = (User) userlist.get(i);
System.out.println(user_temp.getAge() + "," + user_temp.getName());
}
}
}
类用户{
字符串名;
弦年龄;
公共用户(字符串名称、字符串期限){
this.name=名称;
这个。年龄=年龄;
}
公共字符串getAge(){
回归年龄;
}
公共无效设置(字符串期限){
这个。年龄=年龄;
}
公共字符串getName(){
返回名称;
}
公共void集合名(字符串名){
this.name=名称;
}
}
导入java.util.Comparator;
公共类ComparatorUser实现了Comparator{
公共整数比较(对象arg0、对象arg1){
用户user0=(用户)arg0;
用户user1=(用户)arg1;
int flag=user0.getAge().compareTo(user1.getAge());
如果(标志==0){
返回user0.getName().compareTo(user1.getName());
}否则{
返回标志;
}
}
}
导入java.util.ArrayList;
导入java.util.Collections;
导入java.util.List;
公共类分类测试{
公共静态void main(字符串[]args){
List userlist=new ArrayList();
添加(新用户(“dd”,“4”);
添加(新用户(“aa”,“1”));
添加(新用户(“ee”,“5”);
添加(新用户(“bb”,“2”));
添加(新用户(“ff”,“5”);
添加(新用户(“cc”,“3”));
添加(新用户(“gg”,“6”);
ComparatorUser comparator=新的ComparatorUser();
Collections.sort(userlist,comparator);
对于(int i=0;i
我用这个(只是一个例子,我删掉了,但想法相同)进行降序排序:
@Override
public int compare(Member m1, Member m2) {
double fit1 = m1.getFitness() ;
double fit2 = m2.getFitness() ;
if (fit2>fit1)
return 1;
else if (fit2<fit1)
return -1;
else
return 0;
}
@覆盖
公共整数比较(成员m1、成员m2){
双fit1=m1.getFitness();
双fit2=m2.getFitness();
如果(fit2>fit1)
返回1;
否则,如果(fit2@Rohit Jain的可能重复项,如果我的z是双精度类型,我会得到一个错误无法调用原语类型double上的compareTo(double)
try,return(int)(o1.height-o2.height());
class User {
String name;
String age;
public User(String name, String age) {
this.name = name;
this.age = age;
}
public String getAge() {
return age;
}
public void setAge(String age) {
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}
import java.util.Comparator;
public class ComparatorUser implements Comparator {
public int compare(Object arg0, Object arg1) {
User user0 = (User) arg0;
User user1 = (User) arg1;
int flag = user0.getAge().compareTo(user1.getAge());
if (flag == 0) {
return user0.getName().compareTo(user1.getName());
} else {
return flag;
}
}
}
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
public class SortTest {
public static void main(String[] args) {
List userlist = new ArrayList();
userlist.add(new User("dd", "4"));
userlist.add(new User("aa", "1"));
userlist.add(new User("ee", "5"));
userlist.add(new User("bb", "2"));
userlist.add(new User("ff", "5"));
userlist.add(new User("cc", "3"));
userlist.add(new User("gg", "6"));
ComparatorUser comparator = new ComparatorUser();
Collections.sort(userlist, comparator);
for (int i = 0; i < userlist.size(); i++) {
User user_temp = (User) userlist.get(i);
System.out.println(user_temp.getAge() + "," + user_temp.getName());
}
}
}
@Override
public int compare(Member m1, Member m2) {
double fit1 = m1.getFitness() ;
double fit2 = m2.getFitness() ;
if (fit2>fit1)
return 1;
else if (fit2<fit1)
return -1;
else
return 0;
}