在另一个类中创建一个方法来打印ArrayList中，然后调用它 [英] Creating a method to print ArrayList, then calling it in another class

问题描述

我已经建立了我的班书目一个ArrayList，但我需要它在另一个类打印。

我想我可能把一个ArrayList的印刷进入一个方法，所以那么它可以从不同的类调用;如果我错了，虽然，还有什么可以做我做到这一点？

下面是我的code，以供参考。

 进口的java.util.ArrayList;
公共类书目{公共静态无效的主要（字串[] args）{    书=新的图书（）;    a.setTitle（随机）;
    a.setAuthor（克雷格·罗伯逊）;
    a.setBookID（1847398812）;
    a.setonLoan（假）;
    a.setNumberofLoans（3）;    图书B =新的图书（）;    b.setTitle（最后的避难所）;
    b.setAuthor（克雷格·罗伯逊）;
    b.setBookID（1471127753）;
    b.setonLoan（假）;
    b.setNumberofLoans（2）;    图书C =新的图书（）;    c.setTitle（未唱鸟）;
    c.setAuthor（亚历克斯灰色）;
    c.setBookID（0751548278）;
    c.setonLoan（真）;
    c.setNumberofLoans（7）;    ArrayList的＆LT;图书＆GT;书目=新的ArrayList＆LT;图书＆GT;（）;
    BookList.add（一）;
    BookList.add（二）;
    BookList.add（C）;    诠释计数= BookList.size（）;
    的System.out.println（伯爵：+计数）;
    的System.out.println（）;        对于（图书D：书目）{
            的System.out.println（D）;    }
  }
}
 

要顺应这一点，我在我的图书类中的toString（）方法，这样我就可以打印所有对象。

另外一个问题：我如何将打印每个对象的只是标题和作者

解决方案

创建的静态在图书类的方法将处理的显示

 公共静态无效showBook​​s（ArrayList的＆LT;图书＆GT;书）{
    对于（图书D：书籍）{
        的System.out.println（D）; //调用每个Book对象的'的toString'方法
}
 

和调用它这种方式从主要方法：

 的ArrayList＆LT;图书＆GT;书目=新的ArrayList＆LT;图书＆GT;（）;
BookList.add（一）;
BookList.add（二）;
BookList.add（C）;Book.showBook​​s（书目）; //打印的书籍，一个一个
 

  

我将如何打印每个对象的只是标题和作者？

您可以选择打印标题和作者仅在重写 的toString 你的图书类的方法：

  @覆盖
公共字符串的toString（）{
    //'作家'和; '称号'是'书'类的成员
    回归作者：+ +作家 - 标题：+称号;
}
 

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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