java Arrays类应用

package arrays;

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

public class ArraysExercise01 {
    public static void main(String[] args) {
        Book[]books=new  Book[4];
        books[0]=new Book("红楼梦",100);
        books[1]=new Book("水浒传",90);
        books[2]=new Book("青年文摘",5);
        books[3]=new Book("java从入门到放弃",300);

        Arrays.sort(books, new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                if (!(o1 instanceof Book)||!(o2 instanceof Book)){
                    return 0;
                }
                Book b1=(Book)o1;
                Book b2=(Book)o2;
                //返回的正数还是负数，会影响排序的顺序
                if(b1.getPrice()-b2.getPrice()>0){
                    return 1;
                }else if (b1.getPrice()-b2.getPrice()<0){
                    return -1;
                }else{
                    return 0;
                }

            }
        });

        System.out.println(Arrays.toString(books));
    }
}
class Book{
    private String name;
    private double price;

    public Book(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
       return "Book[name="+name+",price="+price+"]
";
    }
}

结果：

[Book[name=青年文摘,price=5.0]
, Book[name=水浒传,price=90.0]
, Book[name=红楼梦,price=100.0]
, Book[name=java从入门到放弃,price=300.0]
]

1.上面的为实现Comparator接口匿名类，也成为定制排序

2.下面的是让Book实现Comparable接口，完成排序，也成为自然排序

package arrays;

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

public class ArraysExercise01 {
    public static void main(String[] args) {
        Book[]books=new  Book[4];
        books[0]=new Book("红楼梦",100);
        books[1]=new Book("水浒传",90);
        books[2]=new Book("青年文摘",5);
        books[3]=new Book("java从入门到放弃",300);

        /*Arrays.sort(books, new Comparator() {
            @Override
            public int compare(Object o1, Object o2) {
                if (!(o1 instanceof Book)||!(o2 instanceof Book)){
                    return 0;
                }
                Book b1=(Book)o1;
                Book b2=(Book)o2;
                //返回的正数还是负数，会影响排序的顺序
                if(b1.getPrice()-b2.getPrice()>0){
                    return 1;
                }else if (b1.getPrice()-b2.getPrice()<0){
                    return -1;
                }else{
                    return 0;
                }

            }
        });

        System.out.println(Arrays.toString(books));*/

        Arrays.sort(books);
        System.out.println(Arrays.toString(books));

    }
}
class Book implements Comparable{
    private String name;
    private double price;

    public Book(String name, double price) {
        this.name = name;
        this.price = price;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getPrice() {
        return price;
    }

    public void setPrice(double price) {
        this.price = price;
    }

    @Override
    public String toString() {
       return "Book[name="+name+",price="+price+"]
";
    }

    @Override
    public int compareTo(Object o) {
        if (!(o instanceof Book)){
            return 0;
        }
        Book book=(Book)o;
        if (this.getPrice()>book.getPrice()){
            return 1;
        }else if(this.getPrice()>this.getPrice()){
            return 1;
        }else{
            return 0;
        }

    }
}

结果：

[Book[name=红楼梦,price=100.0]
, Book[name=水浒传,price=90.0]
, Book[name=青年文摘,price=5.0]
, Book[name=java从入门到放弃,price=300.0]
]