java - 反序列化ArrayList：[unchecked]需要未经检查的转换：ArrayList <Employee> 找到：ArrayList(Deserialize ArrayList: [unchecked] unchecked conversion required: ArrayList<Employee> found: ArrayList)

Question

I am trying out serializing and deserializing a java application.

(我正在尝试序列化和反序列化Java应用程序。)

It's working but I would like to know if I am doing this process correctly.

(它正在工作，但是我想知道我是否正确地执行了此过程。)

I am serializing the ArrayList;

(我正在序列化ArrayList;)

is this the proper way or should I be serializing the Employee class, but how would I go about that considering we could have many employees?

(这是正确的方法还是应该序列化Employee类，但是考虑到我们可能有很多员工，我将如何处理呢？)

The way I am doing it causes this error which I would like to get rid of:

(我这样做的方式导致此错误，我想摆脱它：)

serialTest.java:40: warning: [unchecked] unchecked conversion employees = (ArrayList) ois.readObject();

(serialTest.java:40：警告：[unchecked]未经检查的转换雇员=（ArrayList）ois.readObject（）;)

required: ArrayList found: ArrayList 1 warning

(必需：找到ArrayList：ArrayList 1警告)

Here is the Employee class: package serialTest;

(这是Employee类：package serialTest;)

import java.io.Serializable;

(导入java.io.Serializable;)

public class Employee implements Serializable {

    int id;
    String firstName;
    String lastName;

    public Employee(int id, String firstName, String lastName) {
        super();
        this.id = id;
        this.firstName = firstName;
        this.lastName = lastName;
    }

    @Override
    public String toString() {
        return "Employee [id=" + id + ", firstName=" + firstName + ", lastName=" + lastName + "]";
    }
}

And here is the main class:

(这是主要的类：)

package serialTest;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;

public class serialTest {

    static ArrayList<Employee> employees = new ArrayList<>();

    public static void main(String[] args) {
        if (args.length > 0) {
            deSerialize();
        } else {
            employees.add(new Employee(1, "John", "Doe"));
            employees.add(new Employee(2, "Jane", "Doe"));
            serialize();
        }
    }

    private static void serialize() {
        System.out.println("Serializing...");
        try {
            try (FileOutputStream fos = new FileOutputStream("employeeData"); ObjectOutputStream oos = new ObjectOutputStream(fos)) {
                oos.writeObject(employees);
            }
        } catch (IOException ioe) {
        }
    }

    private static void deSerialize() {
        System.out.println("DeSerializing...");
        try {
            try (FileInputStream fis = new FileInputStream("employeeData");
                    ObjectInputStream ois = new ObjectInputStream(fis)) {

                employees = (ArrayList) ois.readObject();

            }
        } catch (IOException ioe) {
            System.out.println("File problems");
            return;
        } catch (ClassNotFoundException c) {
            System.out.println("Class problems");
            return;
        }

        for (Employee info : employees) {
            System.out.println(info);
        }
    }
}

  ask by James Mead translate from so

Answer 1

You will have to suppress that warning.

(您将不得不禁止该警告。)

Java doesn't know the actual generic type due to type erasure.

(由于类型擦除，Java不知道实际的泛型类型。)