Java 在构造函数中使用自定义的比较器
我在构造函数中使用比较器时遇到困难。当我尝试以下代码时:Java 在构造函数中使用自定义的比较器,java,sorting,comparator,Java,Sorting,Comparator,我在构造函数中使用比较器时遇到困难。当我尝试以下代码时: InsertionSorter is = new InsertionSorter(bookList.toArray(new Comparable[bookList.size()]), new GenreComparator(), SortType.ASC); 我得到这个错误: no suitable constructor found for InsertionSorter(java.lang.Comparable[],sort.Gen
InsertionSorter is = new InsertionSorter(bookList.toArray(new Comparable[bookList.size()]), new GenreComparator(), SortType.ASC);
我得到这个错误:
no suitable constructor found for InsertionSorter(java.lang.Comparable[],sort.GenreComparator,sort.SortType)
constructor sort.InsertionSorter.InsertionSorter(java.lang.Comparable[],java.util.Comparator<java.lang.Object>,sort.SortType) is not applicable
(actual argument sort.GenreComparator cannot be converted to java.util.Comparator<java.lang.Object> by method invocation conversion)
constructor sort.InsertionSorter.InsertionSorter(java.lang.Comparable[],sort.SortType) is not applicable
(actual and formal argument lists differ in length)
(别担心,我已经进行了检查,以确保在cmp==null
时不会调用此函数。这会导致以下错误:
method compare in interface java.util.Comparator<T> cannot be applied to given types;
required: capture#1 of ? extends java.lang.Object,capture#1 of ? extends java.lang.Object
found: java.lang.Comparable,java.lang.Comparable
reason: actual argument java.lang.Comparable cannot be converted to capture#1 of ? extends java.lang.Object by method invocation conversion
接口java.util.Comparator中的方法compare不能应用于给定类型;
必需:捕获扩展java.lang.Object中的第1个,捕获扩展java.lang.Object中的第1个
找到:java.lang.Compariable,java.lang.Compariable
原因:实际参数java.lang.Comparable无法转换为捕获#1 of?通过方法调用转换扩展java.lang.Object
请注意,我在AbstractSort.java中更改了上述内容,将
Comparable
替换为ComparableGenreComparator
类实现了Comparator
。因此,您无法传递该类需要Comparator
的实例。两者都不兼容
但是,您可以将Comparator
更改为ComparatorGenreComparator
类实现Comparator
。因此,您无法传递需要Comparator
的类的实例。两者都不兼容
不过,您可以将Comparator
更改为ComparatorOkay,这解决了我原来的问题,但现在我尝试在doSort()
方法中使用它时,得到了一些不同的结果。我将对原始帖子进行编辑,以便它实际可用legible@whyles您最好使用doSort()
method generic.好的,谢谢你的帮助!我制作了doSort()
generic(这需要在方法中进行一些转换以理顺所有类型),现在一切都进行得很顺利,这解决了我最初的问题,但现在我尝试在doSort()中使用它时得到了一些不同的东西
method。我将对原始帖子进行编辑,以便它实际上是legible@whyles您最好将doSort()
方法设置为泛型。好的,谢谢您的帮助!我将doSort()
设置为泛型(这需要在方法中进行一些转换以理顺所有类型),现在一切都很顺利
public class Book implements Cloneable, Comparable<Book> {
private Person author; // implementation details of Person don't matter here
private String title, isbn;
private int year;
private BookGenre genre;
public Book(Person authorInit, String titleInit, String isbnInit,
int yearInit, BookGenre genreInit) {
author = authorInit;
title = titleInit;
isbn = isbnInit;
year = yearInit;
genre = genreInit;
}
@Override
public String toString() {
return author.toString() + " " + title + " " + isbn + " " + year
+ " " + genre;
}
@Override
public Object clone() throws CloneNotSupportedException {
return super.clone();
}
@Override
public int compareTo(Book other) {
return author.compareTo(other.author);
}
public Person getAuthor() {
return author;
}
public String getTitle() {
return title;
}
public String getIsbn() {
return isbn;
}
public int getYear() {
return year;
}
public BookGenre getGenre() {
return genre;
}
}
class TitleComparator implements Comparator<Book> {
@Override
public int compare(Book a, Book b) {
return a.getTitle().compareToIgnoreCase(b.getTitle());
}
}
class GenreComparator implements Comparator<Book> {
@Override
public int compare(Book a, Book b) {
return a.getGenre().compareTo(b.getGenre());
}
}
enum BookGenre { COMIC, MYSTERY, SCIENCE, TRAVEL };
cmp.compare(values[j-1], values[j])
method compare in interface java.util.Comparator<T> cannot be applied to given types;
required: capture#1 of ? extends java.lang.Object,capture#1 of ? extends java.lang.Object
found: java.lang.Comparable,java.lang.Comparable
reason: actual argument java.lang.Comparable cannot be converted to capture#1 of ? extends java.lang.Object by method invocation conversion