小编Meh*_*ran的帖子

我知道HashMap 不保证订单.请考虑以下代码:

import java.util.HashMap;
import java.util.Map;

public class SandBox {
    protected static class Book {
        String name;

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

        @Override
        public String toString() {
            return name;
        }
    }

    protected static class MyThread extends Thread {
        @Override
        public void run() {
            super.run();
            final int n = 10;
            Book[] books = new Book[n];
            for (int i=0; i<n; i++)
                books[i] = new Book("b" + i);
            for (Book b : books)
                System.out.print(b + ", ");
            System.out.println();
            HashMap<Book, …