如何在Android中的AsyncTask上返回匿名List或ArrayList

Question

List完成后我有6种不同类型的结果AsyncTask.并且List结果应该返回到Activity.例如:List<A>,List<B>,List<C>,List<D>,List<E>和最后List<F>.

这是我的AsyncTask:

public class myAsync extends AsyncTask<String, String, List> {

    private List resultList;

    @Override
    protected List doInBackground(String... params) {
        //params[0] is url
        //params[1] is type
        callAPI api = new callAPI(params[0], params[1]);
        // According to type api decides type of List and generates
        return api.getJSON(); // returns a List which already parse JSON
    }

    @Override
    protected void onPostExecute(List result) {
        // Result is here now, may be 6 different List type.
        this.resultList = result 
    }

    // returns result
    public List getResultList() { return this.resultList; }
}

我会像这样调用AsyncTask:

myAsync task = new myAsync();
task.execute(params);
List myList = task.getResultList(); // type is uncertain
Log.d("Tag", Integer.toString(myList.size());

你知道,我必须指出<>标签之间的返回类型(Result).如果我选择特定类型List,则不适用于其他类型.

实际上,我已经尝试过返回List<Object>,只有List类型.但是没有用.

我不想用6种不同的Async.是否有可能只用一个解决这个问题AsyncTask？我想我需要匿名列表或类似的东西不确定.有谁能解释一下？

Answer 1

首先,我应该指出,您获取列表的顺序是不正确的.让我来证明:

// Initialize myAsync
myAsync task = new myAsync();

// This will do work for some period of time, this statement DOES NOT 'block'
// till myAsync completes, it will run it in the background
task.execute(params);

// This will return null because by the time you get here, task.execute most
// likely hasn't finished yet.
task.getResultList();

编辑:现在您已经包含了要对列表结果执行的操作,以下是修改onPostExecute方法的方法:

@Override
protected void onPostExecute(List result) {
  Log.d(TAG, "The returned list contains " +result.size()+ "elements");
  // Do anything else you need to with the returned list here
}

总而言之,如果您需要对返回的列表执行任何其他操作(除了打印它们的大小),例如比较,打印项目等,您需要在onPostExecute方法中执行此操作.