Question

我从CreateOne类调用方法Non-Activity，CreateOne方法需要在Object执行后返回Task。所以我在调用Task之后添加了以下行。

task.wait();

但它正在返回错误，如

object not locked by thread before wait()

这是我的完整代码：

public class MyStitchHelper
{
    public Object CreateOne(Map<String, Object> map) throws InterruptedException
    {
        Object returnObject = null;
        Document mapDoc = new Document(map);
        ArrayList<Document> list = new ArrayList<>();

        list.add(mapDoc);

        Document itemsDocument = new Document("items", list);
        PipelineStage itemsStage = new PipelineStage("literal", "", itemsDocument);
        Document AuthDocument = new Document();
        AuthDocument.append("database","my_db");
        AuthDocument.append("collection", _collectionName);
        PipelineStage AuthStage = new PipelineStage("insert", "mongodb-atlas", AuthDocument);


        Task<List<Object>> task = _client.executePipeline(itemsStage, AuthStage);

        task.wait();

        if(task.isSuccessful())
        {
            Log.e("UserDAL", task.getResult().toString());
            returnObject = task.getResult();
        }
        else
        {
            Log.e("UserDAL", "Error Adding Collectionsss");
            task.addOnFailureListener(new OnFailureListener() {
            @Override
            public void onFailure(@NonNull Exception e) {
                Log.e("UserDAL", "" + e.getMessage());
            }
            });
        }

        return returnObject;
    }
}

通话方式：

public void AddUser()
{
    MyStitchHelper DBHelper = new MyStitchHelper();

    Map<String, Object> map = new HashMap<>();

        map.put(User.Columns.EMAIL,user.get_userName());
        map.put(User.Columns.PASSWORD, user.get_password());
        map.put(User.BaseColumns.CREATED_DATE, Calendar.getInstance().getTime());

        Document doc = (Document) DBHelper.CreateOne(map);
}

首先，实现是否正确我想要做的只是创建一个新用户并在创建后返回Document对象。

错误抛出的原因是什么？

任何想法？

Answer 1

这是关于类似问题的Question。它可能是有用的

总之，回答：

引用：“这是等待和通知的意思：”

private Queue<Product> q = ...;
private Object lock = new Object();

void produceSomething(...) {
    Product p = reallyProduceSomething();
    synchronized(lock) {
        q.add(p);
        lock.notify();
    }
}

void consumeSomething(...) {
    Product p = null;
    synchronized(lock) {
        while (q.peek() == null) {
            lock.wait();
        }
        p = q.remove();
    }
    reallyConsume(p);
}

在Non Activity上的Android应用中等待之前，对象未被线程锁定

1 个答案: