可以从从文件读取的对象中转换 Collections.synchronizedList() 吗？答案

【问题标题】：Its possible to cast an Collections.synchronizedList() from object read from file?可以从从文件读取的对象中转换 Collections.synchronizedList() 吗？
【发布时间】：2016-10-20 22:18:34
【问题描述】：

我想从我之前保存该列表的文件中读取Collections.synchronizedList(ArrayList<>())（这甚至可能吗？）。我得到这个错误：

Exception in thread "main" java.lang.ClassCastException: java.util.Collections$SynchronizedRandomAccessList cannot be cast to java.util.ArrayList
    at RMIServerImpl.loadAuctions(RMIServerImpl.java:247)
    at RMIServerImpl.rmiStart(RMIServerImpl.java:293)
    at RMIServerImpl.main(RMIServerImpl.java:323)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:147)

我的代码：

private List<User> users;

public RMIServerImpl() throws java.rmi.RemoteException{
    super();
    auctions = Collections.synchronizedList(new ArrayList<>()); 
}
public void saveAuctions(){
    ObjectFile file = new ObjectFile();
    try {
        file.openWrite("auctions");
    } catch (IOException e) {
        System.out.println("Problem opening auctions file(WRITE MODE).");
    }
    try {
        file.writeObject(this.auctions);
    } catch (IOException e) {
        System.out.println("Problem saving auctions");
    }
    try {
        file.closeWrite();
    } catch (IOException e) {
        System.out.println("Problem close auctions file(WRITE MODE).");
    }
}
public void loadAuctions(){
    ObjectFile file = new ObjectFile();
    try {
        file.openRead("auctions");
    } catch (IOException e) {
        System.out.println("Problem opening auctions file(READ MODE)(No auctions found)");
    }

    try {
        this.auctions= (ArrayList<Auction>) file.readObject();//PROBLEM OCCURS HERE
    } catch (IOException | ClassNotFoundException e) {
        System.out.println("Problem loading auctions");
    }

    try {
        file.closeRead();
    } catch (IOException e) {
        System.out.println("Problem closing auctions file(READ MODE)");
    }
}

【问题讨论】：

Collections.synchronizedList 不返回 ArrayList，它返回可以包装它的列表，但它不是 ArrayList 本身，也不是扩展它。
你正在阅读的文件怎么样？
这是一个目标文件，我保存我的拍卖列表。
拍卖定义为：private List<Auction> auctions;
您是否尝试将其转换为 (List<Action>) 而不是 (ArrayList<Auction>)？

标签： java list exception collections synchronization

【解决方案1】：

将其转换为 (List) 而不是 (ArrayList) 解决了它

【讨论】：