三个代码需要组合在一个代码中[关闭]

Question

如下所示，我有三个代码，我不知道如何将它们组合成一个代码，因此我可以运行它并打印出书“9780345917430”是否在列表中

import java.util.ArrayList;

import java.util.List;

public class Book {

    private String isbn;
    private String title;
    private String author;

    public Book(String isbn, String title, String author) {
        this.isbn = isbn;
        this.title = title;
        this.author = author;
    }

    public String toString() {
        return author + ": " + title;
    }

    public boolean equals(Object x){
        if (x instanceof Book){
            return isbn.equals(((Book) x).isbn);
        } else {
            return false;
        }
    }

}

我有一个清单

List<Book> list = new ArrayList<Book>();

我有一个 if 语句

if (list.contains(new Book("9780345917430", null, null))) {
    System.out.println("Boken finns");
}

我正在考虑将列表放在public class Book { 下，我想将 if 语句放在 main 方法中，但由于public class Book { 而我无法做到这一点的问题涉及public 如何将所有这些组合在一个代码中以便我可以在 Eclipse 中运行它？？？ 谢谢

Answer 1

Eclipse 或任何 IDE 都可以一次编译整个项目。只需创建单独的文件，然后运行具有public static void main(String[] args) { 方法的类。

示例： BookExample.java

public class BookExample {
    private static List<Book> list = new ArrayList<Book>();

    public static void main(String[] args) {
        if (list.contains(new Book("9780345917430", null, null)) {
            System.out.println("Boken finns");
        }
    }
}

Book.java

import java.util.ArrayList;

import java.util.List;

public class Book {

    private String isbn;
    private String title;
    private String author;

    public Book(String isbn, String title, String author) {
        this.isbn = isbn;
        this.title = title;
        this.author = author;
    }

    public String toString() {
        return author + ": " + title;
    }

    public boolean equals(Object x){
        if (x instanceof Book){
            return isbn.equals(((Book) x).isbn);
        } else {
            return false;
        }
    }

}

Answer 2

  import java.util.ArrayList;

import java.util.List;

public class Book {

private String isbn;
private String title;
private String author;

public Book(String isbn, String title, String author) {
    this.isbn = isbn;
    this.title = title;
    this.author = author;
}

public String toString() {
    return author + ": " + title;
}

public boolean equals(Object x){
    if (x instanceof Book){
        return isbn.equals(((Book) x).isbn);
    } else {
        return false;
    }
}

同一个类中的另一种方法

 public static void main(String[] args){
     List<Book> books = new ArrayList<Book>();
     if (list.contains(new Book("9780345917430", null, null))) {
     System.out.println("Boken finns");
   }
}

Answer 3

你可以试试这个

import java.util.ArrayList;

import java.util.List;

public class Book {

    private String isbn;
    private String title;
    private String author;

    public static List<Book> list = new ArrayList<Book>();

    public Book(String isbn, String title, String author) {
        this.isbn = isbn;
        this.title = title;
        this.author = author;
    }

    public String toString() {
        return author + ": " + title;
    }

    public boolean equals(Object x){
        if (x instanceof Book){
            return isbn.equals(((Book) x).isbn);
        } else {
            return false;
        }
    }

    public static void main(String arg[])
    {

    if (list.contains(new Book("9780345917430", null, null))) 
    {
            System.out.println("Boken finns");
    }
    }
}

Answer 4

你只需要从下面的其他类的主函数中调用它

        public class classname {
        List<Book> list = new ArrayList<Book>();
        public static void main(String[] args) {
            if (list.contains(new Book("9780345917430", null, null))) {
                System.out.println("Boken finns");
            }
        } 
    }