java 没有合适的排序错误方法
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no suitable method for sort error
提问by Matthew Optional Meehan
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Collection;
public class ClearlyAnArrayList
{
public static void main(String[] args){
Scanner kb=new Scanner(System.in);
ArrayList<Integer>ints=new ArrayList<Integer>();
int num=kb.nextInt();
while(num!=-1){
ints.add(num);
}
sortPrint(ints);
}
public static void sortPrint(Collection<Integer>ints){
Collections.sort(ints);
for(Integer i:ints){
System.out.printf("%d\n",i);
}
}
}
This is the code I'm compiling with blueJ When I compile it I get a lengthy error which starts off "
no suitable method for sort(java.util.Collection<java.lang.Integer>)" and then goes on to say more stuff I don't understand.
这是我用 blueJ 编译的代码 当我编译它时，我得到一个冗长的错误，从“
no suitable method for sort(java.util.Collection<java.lang.Integer>)”开始，然后继续说更多我不明白的东西。
The solution to this was that I was using a List which is not a collection and Collections.sort()expects a List
对此的解决方案是我使用的是一个列表，它不是一个集合，而是Collections.sort()一个列表
Also is there a better way than singular
importstatements for all my utils?
import对于我的所有实用程序，还有比单数语句更好的方法吗？
The solution given was
给出的解决方案是
import java.util.*;
采纳答案by mprabhat
Collections.sortexpects a Listand not Collection, so change your sortPrintmethod
From
Collections.sort期望 aList和 not Collection，所以改变你的sortPrint方法 From
Collection<Integer>ints
To
到
List<Integer> ints
Offtopic:
无关：
Instead of working directly on concrete classes program to an interface.
而不是直接在具体的类上工作，编程到接口。
Prefer
更喜欢
List<Integer> ints = new ArrayList<Integer>();
Over
超过
ArrayList<Integer> ints = new ArrayList<Integer>();
回答by Shawn
what about just doing this:
只是这样做怎么样：
public static void sortPrint(List<Integer> ints){
Collections.sort(ints);
for(Integer i:ints){
System.out.printf("%d\n",i);
}
Collections.sort()is only for List
Collections.sort()只为 List
回答by tibo
For your import
为您的进口
import java.util.*;
The the sort method sort a List, not a collection, so change you declaration to :
sort 方法对列表而不是集合进行排序，因此将您的声明更改为：
public static void sortPrint(List<Integer> ints)
You can also have a collection that sort itself during insertion, your program become :
你也可以有一个在插入过程中自行排序的集合，你的程序变成：
public static void main(String[] args){
Scanner kb=new Scanner(System.in);
TreeSet<Integer>ints=new TreeSet<Integer>();
int num=kb.nextInt();
while(num!=-1){
ints.add(num);
}
//already sorted
}
Warning, in a Set (and so in a TreeSet) you cannot have the same element twice
警告，在 Set 中（在 TreeSet 中也是如此）你不能有两次相同的元素
回答by BachT
Read the documentations (or try to Ctrl + Space for information).
阅读文档（或尝试按 Ctrl + Space 获取信息）。
java.until.Collectionsdocumentation: here
java.until.Collections文档：这里
This class only supports Collections.sort(list)and Collections.sort(list,comparator), so you can not sort the Collection. Try Listinstead
这个类只支持Collections.sort(list)和Collections.sort(list,comparator)，所以你不能对Collection. 尝试List代替
