Question

首先，我所做的是将一个ArrayList作为ann对象写入.txt文件，我要做的是将这些对象读回一个数组并显示数组（与第一步相反）。传递给功能的arraylist是推销员和技术人员，他们使用参数名称，编号，目标，特性等扩展员工。当我尝试编译时，我收到此错误。

线程中的异常＆＃34; main＆＃34; java.lang.ClassCastException：java.util.ArrayList无法强制转换为Employee 在FileIO.readObject（FileIO.java:165）在UseCompany.main（UseCompany.java:61）

尝试从文本文件中读回对象

ArrayList<Employee> use_company_arraylist2 = FileIO.("C:\\Users\\Saad\\Documents\\writeObjectMethod.txt"");
use_company_arraylist2 = FileIO.readObject("C:\\Users\\Saad\\Documents\\writeObjectMethod.txt");

写入文本文件代码的对象：

public static void writeObject(ArrayList<Employee> array_of_employee, String    filename)
{
  try{

     //create file stream and write array to file using stream using objectoutput stream
     FileOutputStream fle = new FileOutputStream("c:\\Users\\Saad\\Documents\\writeObjectMethod.txt");
     ObjectOutputStream oos = new ObjectOutputStream(fle);
     oos.writeObject(array_of_employee);
     oos.close();
     fle.close();
  }

  catch(FileNotFoundException filenotfound)
  {  
     System.out.println("FILE NOTE FOUND");
  }
  catch(IOException ioerror)
  {
     System.out.println("input or output error");
  }


}//end writeObject

来自文本文件代码的阅读对象：

 public static ArrayList<Employee> readObject (String filename)
{
  ArrayList<Employee> newArrayList = new ArrayList<Employee>();

  try 
  {  
     FileInputStream readfle = new FileInputStream(filename);
     ObjectInputStream readobjectfile = new ObjectInputStream(new BufferedInputStream(readfle));
     newArrayList.add((Employee)readobjectfile.readObject());

  }

  catch(ClassNotFoundException clasnfd)
  {
     System.out.println("class error?");
  }


  catch(IOException ioerror)
  {
     System.out.println("input or output error");
  }
  return newArrayList;

}//end readObject

Answer 1

Arraylist类型的对象无法转换为Employee类的对象。

这会奏效 ArrayList list = new ArrayList（）; list.add（new Employee（））;

// for writing arraylist object to file
new ObjectOutputStream(new FileOutputStream(new File("a.txt"))).writeObject(list);

// for reading array list from file
ArrayList<Employee> anotherList = (ArrayList<Employee>) new ObjectInputStream(new FileInputStream(new File("a.txt"))).readObject();

System.out.println(anotherList.size());

如何从.txt文件中读取数组的对象？

1 个答案: