ArrayList object 及其迭代器 object 不工作

Question

如标题所述，ArrayList 及其迭代器不起作用。不知道为什么。 ArrayList 应该期望 Employees 并且它正在获取它。那为什么迭代器没有给出正确的 objects？有什么帮助吗？

代码：

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

class Employee implements Serializable
{
    private int empid;
    private String name,desig;
    private double salary;
    
    private static final long serialVersionUID=1;
    
    Employee(int empid,String name,String desig, double salary)
    {
        this.empid=empid;
        this.name=name;
        this.desig=desig;
        this.salary=salary;
    }
    
    Employee()
    {}

    @Override
    public String toString()
    {
        return "Employee [empid=" + empid + ", name=" + name + ", desig=" + desig + ", salary=" + salary + "]";
    }
    
}
    
    /**
     * This class is used for checking the serializability of the objects.
     */
public class CollectionsAndSerializabilityPractice
{
    public static void main(String[] args)
    {
        List<Employee> listOfEmployees= new ArrayList<Employee>();
        
        for(int i=1; i<=4; i++)
        {
            listOfEmployees.add(new Employee(i, "Employee"+i, "Manager", 25000+i));
        }
        
        System.out.println("Before serialisation:");
        
        Iterator<Employee> iterate=listOfEmployees.iterator();
        while(iterate.hasNext())
        {
            iterate.next().toString();
            System.out.println();
        }
        
        try(FileOutputStream FOS= new FileOutputStream("Output.txt");)
        {
            ObjectOutputStream OOS=new ObjectOutputStream(FOS);
            
            OOS.writeObject(listOfEmployees);
        }
        catch (Exception e1)
        {
            e1.printStackTrace();
        }
        
        try(FileInputStream FIS= new FileInputStream("Output.txt");)
        {
            ObjectInputStream OIS=new ObjectInputStream(FIS);
            
         listOfEmployees=(List<Employee>)OIS.readObject();
         iterate=listOfEmployees.iterator();
            
            System.out.println("After deserialisation:");

            while(iterate.hasNext())
            {
                iterate.next().toString();
                System.out.println();
            }
        }
        catch (Exception e1)
        {
            e1.printStackTrace();
        }
        
        
    }

}

我无法理解为什么 toString 方法不起作用？有人可以向我详细解释一下这个问题吗？非常感谢任何好的解释。输出：

Answer 1

改变

        while(iterate.hasNext())
        {
            iterate.next().toString();
            System.out.println();
        }

到

        while(iterate.hasNext())
        {
            System.out.println(iterate.next().toString);
        }

您只使用无参数 System.out.println(); 语句打印换行符。你从未将 iterate.next().toString(); 的结果分配给任何东西，所以它丢失了。

ArrayList object 及其迭代器 object 不工作

ArrayList object and its iterator object not working

java

collections