可调用不从类返回任何内容

Question

我正在做一个应用程序，它可以抓取一个网站并获取一些图像，工作正常，我创建了一个ThreadPoolExecutor和一些可调用的，但是当我尝试从我创建的可调用对象中获取结果时，我无法做到，它会转到ExecutionException。

这是刮板类：

public class ImageScraper implements Callable<String>{
Context context = null;
public Logo logoActivity;
Document[] doc = new Document[1];
List<ImageObject> imageList = new ArrayList<ImageObject>();
int pagAnterior;
String url;
int pag;

public ImageScraper(Logo act, String url, int pag, int pagAnterior) {
this.logoActivity = act;
this.url = url;
this.pag = pag;
this.pagAnterior = pagAnterior;
context = act.getApplication();
}
@Override
public String call() throws Exception {
getResponse(url,pag);
getImages(doc[0]);
Log.i("listaaa", "listaa  : "+imageList.size());
String something = "got something";
return something;
}

public void getImages(Document docfinal)  {
Log.i("Documento1", "documento1  : "+docfinal);
Elements entradas = docfinal.select("img[src]");
Elements titulo = doc[0].select("title");
String tituloPagina = titulo.text();
String urlImage = "";
if(!tituloPagina.toLowerCase().contains("page "+pagAnterior)) {
for (Element elem : entradas) {
if (elem.attr("abs:src").toLowerCase().contains("mfiles")) {
urlImage = elem.attr("abs:src").replace("thumb-", "");
Log.i("GridVerticalFragment", "Pillando url: " + urlImage);
ImageObject image = new ImageObject(urlImage);
Log.i("GridVerticalFragment", "Url Pillada: " + image.getUrl());
imageList.add(image);
}
}
}
Log.i("Logo", "Lista2: "+imageList.size());
}

public void getResponse(String urlRoot, int pagina) {
Log.i("GridVerticalLayaout", "Pagina: "+pagina);
String url;
String urlFinal = "";
if(pagina==0){
url = urlRoot;
urlFinal = url;
}else{
url = urlRoot.concat("?page="+Integer.toString(pagina));
urlFinal = url;
}
RequestQueue rq = Volley.newRequestQueue(context);
Log.i("GridVerticalLayaout", "fuuck: "+url);
Log.i("GridVerticalLayaout", "lool: "+urlFinal);
StringRequest stringRequest = new StringRequest(Request.Method.GET, urlFinal,
new Response.Listener<String>() {
@Override
public void onResponse(String response) {
// Do something with the response
doc[0] = Jsoup.parse(response);
getImages(doc[0]);
}
},
new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
// Handle error
Log.e("ERROR", "Error occurred ", error);
}
});
rq.add(stringRequest );
}
}

这是主要类：

public class Logo extends AppCompatActivity {

public List<ImageObject> GlobalImageList = new ArrayList<ImageObject>() ;
Document[] doc = new Document[1];
String url;
int pagAnterior = 0;
int i = 0;
Context context = null;
public ThreadPoolExecutor executor;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_logo);
getSupportActionBar().hide();
Collection<Callable<String>> callableList = new ArrayList<>();
context = getApplication();
int NUMBER_OF_CORES = Runtime.getRuntime().availableProcessors();
executor = new ThreadPoolExecutor(
NUMBER_OF_CORES*2,
NUMBER_OF_CORES*2,
60L,
TimeUnit.SECONDS,
new LinkedBlockingQueue<Runnable>()
);

while(i<4){
callableList.add(new ImageScraper(this,"www.google.es,i,i-1););
i++;
}
List<Future<String>> result = null;
try {
result = executor.invokeAll(callableList);
} catch (InterruptedException e) {
Log.i("Fallo", "Fallo");
e.printStackTrace();
}
for (Future a : result) {
String SingleImageList = null;
try {
SingleImageList = (String) a.get();
Log.i("Single", "Single"+SingleImageList);
} catch (InterruptedException e) {
Log.i("Fallo3", "Fallo3");
e.printStackTrace();
} catch (ExecutionException e) {
Log.i("Fallo2", "Fallo2");
e.printStackTrace();
}

}
}

}

这不会返回任何东西，但抓取器完成他的工作，(getImages(( 和 getResponse(( 完成工作并更新列表，相反，如果在 MainClass 中的这部分代码中：

while(i<4){
callableList.add(new ImageScraper(this,"www.google.es,i,i-1););
i++;
}

如果我为此更改它(该类不称为在类中创建可调用对象(，它可以工作，返回字符串：

while(i<4){
callableList.add(new Callable<String>() {
public String call() throws Exception {
return "haha";
}
});
i++;
}

有人可以帮助我吗？我一直在阅读很多，根据我读过的内容，我在刮板课上的东西很好，但我仍然不明白。

抱歉英语不好，我试图:)，我不想返回一个字符串，我想返回一个 ArrayList，我在代码中返回一个字符串，因为认为返回 ArrayList 有问题，但似乎不是这样，再次，谢谢！

Answer 1

请检查这行代码

while(i<4){
callableList.add(new ImageScraper(this,"www.google.es,i,i-1););
i++;
}    

你没有关闭双引号！ 相反，请尝试此代码

while(i<4){
callableList.add(new ImageScraper(this,"www.google.es",i,i-1););
i++;
}