Java常用类之比较器的使用详解

import java.util.Arrays;

public class ComparableTest {
    public static void main(String[] args) {
        String[] arr = new String[]{"aniu","tom","tony","lisa"};
        Arrays.sort(arr);
        System.out.println(Arrays.toString(arr));
    }
}

package 比较器;

import java.util.Arrays;

public class ComparableDemo {
    public static void main(String[] args) {
        Books[] book = new Books[4];
        book[0] = new Books("The Beautiful and the Damned",68);
        book[1] = new Books("Where Angels Fear to Tread",45);
        book[2] = new Books("These Lovers Fled Away",35);
        book[3] = new Books("The Left Hand of Darkness",58);

        Arrays.sort(book);
        for(Books item:book){
            System.out.println(item.toString());
        }
        //System.out.println(Arrays.toString(book));
    }
}

class Books implements Comparable{
    String name;
    double price;
    public Books(String name, double price) {
        this.name = name;
        this.price = price;
    }
    //重写compareTo
    @Override
    public int compareTo(Object o) {
        //按照图书价格从小到大排序
        if (o instanceof Books){
            Books b = (Books) o;
            if(this.price>b.price){
                return 1;
            }else if(this.price<b.price) {
                return -1;
            }else{
                return 0;
            }
        }
        throw new RuntimeException("传入的数据类型不一致！");
    }
    //重写 toString
    @Override
    public String toString() {
        return "Books{" +
                "name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}

package 比较器;

import java.util.Arrays;
import java.util.Comparator;

public class ComparatorDemo {
    public static void main(String[] args) {
        Book[] book = new Book[4];
        book[0] = new Book("The Beautiful and the Damned",68);
        book[1] = new Book("Where Angels Fear to Tread",45);
        book[2] = new Book("These Lovers Fled Away",35);
        book[3] = new Book("The Left Hand of Darkness",58);

        Arrays.sort(book, new Comparator(){
            //按照价格从大到小排
            @Override
            public int compare(Object o1, Object o2) {
                if(o1 instanceof Book && o2 instanceof Book){
                    Book b1 = (Book)o1;
                    Book b2 = (Book)o2;
                    return -Double.compare(b1.price,b2.price); //这里我们直接调用Double的compare方法
                }
                throw new RuntimeException("传入的数据类型不一致！");
            }
        });
        for(Book item:book){
            System.out.println(item.toString());
        }
        //System.out.println(Arrays.toString(book));
    }
}

class Book{
    String name;
    double price;
    public Book(String name, double price) {
        this.name = name;
        this.price = price;
    }
    //重写 toString
    @Override
    public String toString() {
        return "Book{" +
                "name='" + name + '\'' +
                ", price=" + price +
                '}';
    }
}