[英]Creating a method to print ArrayList, then calling it in another class
I've built an Arraylist in My class 'BookList', but I need it to print in another class. 我已经在“ BookList”类中构建了一个Arraylist,但是我需要它才能在另一个类中打印。
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; 我想我可能必须将Arraylist的打印转换为方法,以便可以从另一个类中调用它; if I am wrong though, what else could I do to accomplish this?
如果我错了,我还能做些什么呢?
Below is my code, for reference. 下面是我的代码,以供参考。
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. 为此,我在'Book'类中具有toString()方法,因此可以打印所有对象。
An additional question: How would I print just the title and author of each object? 另一个问题:如何打印每个对象的标题和作者?
Create a static method in your Book
class that will handle the display: 在
Book
类中创建一个静态方法来处理显示:
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: 并从main方法中以这种方式调用它:
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?
如何仅打印每个对象的标题和作者?
You can choose to print the title
and author
only in the overriden toString
method of your Book
class: 您可以选择仅在
Book
类的重写 toString
方法中打印title
和author
:
@Override
public String toString() {
// 'author' & 'title' are members of the 'Book' class
return "Author: " + author + "- Title: " + title;
}
Override the BookList tostring method like so : 像这样重写BookList tostring方法:
public class BookList{
@Override
public String toString(){
// Return some string here
}
}
Then just use it normally. 然后只需正常使用即可。
System.out.println(myBookList);
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