创建一个打印 ArrayList 的方法，然后在另一个类中调用它 [英] Creating a method to print ArrayList, then calling it in another class

问题描述

我已经在我的类BookList"中构建了一个 Arraylist，但我需要在另一个类中打印它.

我想我可能不得不把一个Arraylist的打印变成一个方法，这样才能从不同的类中调用它；如果我错了，我还能做些什么来实现这一目标?

以下是我的代码，供参考.

import java.util.ArrayList;公共类书单{公共静态无效主(字符串 [] args){Book a = new Book();a.setTitle("随机");a.setAuthor("克雷格罗伯逊");a.setBookID("1847398812");a.setonLoan(false);a.setNumberofLoans(3);书 b = 新书()；b.setTitle("最后的避难所");b.setAuthor("克雷格罗伯逊");b.setBookID("1471127753");b.setonLoan(false);b.setNumberofLoans(2);书 c = 新书();c.setTitle("不唱歌的鸟");c.setAuthor("Alex Gray");c.setBookID("0751548278");c.setonLoan(真);c.setNumberofLoans(7);ArrayListBookList = new ArrayList();BookList.add(a);BookList.add(b);BookList.add(c);int count = BookList.size();System.out.println("计数:" + count);System.out.println("");for (Book d : BookList){System.out.println(d);}}}

为此，我的Book"类中有 toString() 方法，因此我可以打印所有对象.

另一个问题:如何只打印每个对象的标题和作者?

解决方案

在您的 Book 类中创建一个 static 方法来处理显示:

public static void showBooks(ArrayList books) {对于(书籍 d:书籍){System.out.println(d);//在每个 Book 对象上调用 'toString' 方法}

并从主方法中这样调用它:

ArrayListBookList = new ArrayList();BookList.add(a);BookList.add(b);BookList.add(c);Book.showBooks(BookList);//一本一本地打印书籍

<块引用>

如何只打印每个对象的标题和作者?

你可以选择只在你的overriden toString 方法中打印title 和author>Book 课:

@Override公共字符串 toString() {//'作者' &'title' 是 'Book' 类的成员返回作者:"+作者+-标题:"+标题；}

I've built an Arraylist in My class 'BookList', but I need it to print in another class.

I think I may have to turn the printing of an Arraylist into a method, so then it can be called from a different class; if I am wrong though, what else could I do to accomplish this?

Below is my code, for reference.

import java.util.ArrayList;


public class BookList {

public static void main (String[] args){

    Book a = new Book();

    a.setTitle("Random ");
    a.setAuthor("Craig Robertson");
    a.setBookID("1847398812");
    a.setonLoan(false);
    a.setNumberofLoans(3);

    Book b = new Book();

    b.setTitle("The Last Refuge");
    b.setAuthor("Craig Robertson");
    b.setBookID("1471127753");
    b.setonLoan(false);
    b.setNumberofLoans(2);

    Book c = new Book();

    c.setTitle("The Bird That Did Not Sing");
    c.setAuthor("Alex Gray");
    c.setBookID("0751548278");
    c.setonLoan(true);
    c.setNumberofLoans(7);

    ArrayList<Book> BookList = new ArrayList<Book>();
    BookList.add(a);
    BookList.add(b);
    BookList.add(c);

    int count = BookList.size();
    System.out.println("Count: " + count);
    System.out.println("");

        for (Book  d : BookList){
            System.out.println(d);

    }   
  }
}

To go with this, I have the toString() method in my 'Book' class, so I could print all objects.

An additional question: How would I print just the title and author of each object?

解决方案

Create a static method in your Book class that will handle the display:

public static void showBooks(ArrayList<Book> books) {
    for (Book  d : Books){
        System.out.println(d); // calls the 'toString' method on each Book object
}

And call it this way from the main method:

ArrayList<Book> BookList = new ArrayList<Book>();
BookList.add(a);
BookList.add(b);
BookList.add(c);

Book.showBooks(BookList); // prints the books, one by one

How would I print just the title and author of each object?

You can choose to print the title and author only in the overriden toString method of your Book class:

@Override
public String toString() {
    // 'author' & 'title' are members of the 'Book' class
    return "Author: " + author + "- Title: " + title;
}

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