需要类、接口或枚举（Java）

为什么导入这些会导致错误

import java.util.*;
import java.util.List;
import java.util.Arrays;

//一个简短的演示示例

package bookpack;

class Book{
    private String title;
    private String author;
    private int pubDate;

    Book(String t, String a, int p){
        title = t;
        author = a;
        pubDate = p;
    }

    void show(){
        System.out.println(title);
        System.out.println(author);
        System.out.println(pubDate);
        System.out.println();
    }
}

class BookDemo{
    public static void main (String[] args) {
        Book books[] = new Book[5];

        books[0] = new Book("JAVA: A beginner Guide", "Schidt", 2010);
        books[1] = new Book("C++ :Guide", "Adam", 2013);
        books[2] = new Book("F+", "Ben", 2014);

        for(int i=0; i < books.length; i++){
            books[i].show();
        }
    }
}

---

如果有人能帮我解决问题，我将不胜感激。：）

写

包书在文件顶部，首先是所有导入

像这样：

package bookpack;

import java.util.*;
import java.util.List;
import java.util.Arrays;
//A short demonstration example.

class Book{
   ...
   ...

您应该在启动软件包之前阅读

进口货物应在包装声明之后

package bookpack;

import java.util.*;
import java.util.List;
import java.util.Arrays;

//A short demonstration example.

class Book{
...

package bookpack;

import java.util.*;
import java.util.List;
import java.util.Arrays;

//A short demonstration example.

class Book{
...