方法检查ArrayList中对象的变量

Question

package Ex1;

import java.text.NumberFormat;

public class Textbook 
{
private String category, title, author;
private int year;
private double price;

public Textbook (String category, String title, String author, int year,
                 double price)
{
    this.category = category;
    this.title = title;
    this.author = author;
    this.year = year;
    this.price = price;
}

public String toString()
{
    NumberFormat fmt = NumberFormat.getCurrencyInstance();

    String description;

    description = "Category: " + category + "\n";
    description += "Title: " + title + "\n";
    description += "Author: " + author + "\n";
    description += "Year: " + year + "\n";
    description += "Price: " + fmt.format(price) + "\n" + "\n";

    return description;
}

}

目录类

package Ex1;

import java.util.ArrayList;

public class Catalogue 
{
private ArrayList <Textbook> catalogue;

public Catalogue ()
{
    catalogue = new ArrayList<Textbook>();
}

public void addTextbook (Textbook t) 
{
    catalogue.add(t);
}

public boolean existTextbook(String title, String author)
{

}

public void deleteTextbook(String title)
{   

}

public String toString()
{
    return catalogue.toString(); 
}
}

驱动程序类

package Ex1;

public class Drivermain 
{
public static void main(String[] args) 
{
    Textbook javaBook = new Textbook ("Computer Science", 
            "Java Software Solutions", "Lewis/Loftus", 2015, 163.45);

    Textbook dataBook = new Textbook ("Computer Science", 
            "Data Structures and Algorithm Analysis in Java,", 
            "Mark A. Weiss", 2015, 181.90);

    Textbook calcBook = new Textbook ("Mathematics", 
            "Calculus Plus NEW MyMathLab", "Briggs/Cochran/Gillett",
            2015, 236.90);

    Textbook osBook = new Textbook ("Computer Science", 
            "Operating Systems: Internals and Design Principles",
            "William Stallings", 2015, 205.70);

    Textbook historyBook = new Textbook ("History", 
            "History of the Canadian Peoples: Beginnings to 1867, Vol. 1",
            "Conard/Finkel/Fyson", 2015, 96.90);

    Catalogue bookCatalogue = new Catalogue();

    bookCatalogue.addTextbook(javaBook);
    bookCatalogue.addTextbook(dataBook);
    bookCatalogue.addTextbook(calcBook);
    bookCatalogue.addTextbook(osBook);
    bookCatalogue.addTextbook(historyBook);

    System.out.println(bookCatalogue);


    bookCatalogue.existTextbook("Java Software Solutions", "Lewis/Loftus");
    bookCatalogue.deleteTextbook("Java Software Solutions");

    }
}

Answer 1

我认为，与其使用集合中的方法，您可能希望自己处理查找Arraylist的问题。

我没有使用for each循环（只是for循环），因为for delete会导致并发修改异常。

 package Ex1;

import java.util.ArrayList;

public class Catalogue 
{
private ArrayList <Textbook> catalogue;

public Catalogue ()
{
    catalogue = new ArrayList<Textbook>();
}

public void addTextbook (Textbook t) 
{
    catalogue.add(t);
 }

public boolean existTextbook(String title, String author)
{
    for(int i =0; i<catalogue.Size(); i++){
       Textbook t = catalogue.get(i);
       //you'll want getter and setter methods
       if(t.author.equals(author)&&t.title.equals(title))
           return truel
    }
}

public void deleteTextbook(String title)
{   
    for(int i =0; i<catalogue.Size(); i++){
       Textbook t = catalogue.get(i);
       if(t.title.equals(title)){
          catalogue.remove(i);
       }
    }

}

public String toString()
{
    return catalogue.toString(); 
}
}

编码快乐！如果你有任何问题请留言。