我試圖從查詢的字符串中獲取谷歌搜索的匹配。Java:錯誤地使用GSon? (空指針異常)
public class Utils {
public static int googleHits(String query) throws IOException {
String googleAjax = "http://ajax.googleapis.com/ajax/services/search/web?v=1.0&q=";
String json = stringOfUrl(googleAjax + query);
JsonObject hits = new Gson().fromJson(json, JsonObject.class);
return hits.get("estimatedResultCount").getAsInt();
}
public static String stringOfUrl(String addr) throws IOException {
ByteArrayOutputStream output = new ByteArrayOutputStream();
URL url = new URL(addr);
IOUtils.copy(url.openStream(), output);
return output.toString();
}
public static void main(String[] args) throws URISyntaxException, IOException {
System.out.println(googleHits("odp"));
}
}
下拋出異常:
Exception in thread "main" java.lang.NullPointerException
at odp.compling.Utils.googleHits(Utils.java:48)
at odp.compling.Utils.main(Utils.java:59)
我在做什麼錯誤?我應該爲Json返回定義一個完整的對象嗎?這看起來過分了,因爲我想要做的就是獲得一個價值。
僅供參考:returned JSON structure。