Gdx.net.sendHttpRequest中的NullPointerException

Question

我試圖用libGDX寫一點代碼來處理網絡。這裏是一個代碼：

public class Test { 

public static void main(String[] args) { 
    String accessToken = "********"; //a set of symbols, not important because it is specific of request target 
    String userID = "*********"; //also not important 
    String message = "Hello World"; 
    String uri = "method/wall.post?owner_id=" + userID + "&message=" + message + "&access_token=" + accessToken; 
    HttpRequestBuilder requestBuilder = new HttpRequestBuilder(); 
    HttpRequest httpRequest = requestBuilder.newRequest().method(HttpMethods.GET).url("https://api.vk.com/").content(uri).build(); 
    Gdx.net.sendHttpRequest(httpRequest, //Here Eclipse shows NullPointerException 
      null); //But not here 
} 

如果我在瀏覽器中寫這個URL，它的工作原理是正確的。這意味着，這個問題在我身邊。如何解決它？

導致NullPointerException異常對象的值的總結：

Answer 1

你在你的程序的靜態主入口點編寫這些代碼。您的Gdx尚未加載，因此Gdx在此時仍然爲空。

創建一個無靜態類，並將其代碼放入其構造函數中，並在該靜態入口點中初始化該類。

public class WebTest() 
{ 
    public WebTest() 
    { 
    String accessToken = "********"; //a set of symbols, not important because it is specific of request target 
    String userID = "*********"; //also not important 
    String message = "Hello World"; 
    String uri = "method/wall.post?owner_id=" + userID + "&message=" + message + "&access_token=" + accessToken; 
    HttpRequestBuilder requestBuilder = new HttpRequestBuilder(); 
    HttpRequest httpRequest = requestBuilder.newRequest().method(HttpMethods.GET).url("https://api.vk.com/").content(uri).build(); 
    Gdx.net.sendHttpRequest(httpRequest, //Here Eclipse shows NullPointerException 
      null); //But not here 
    } 
} 

public class Test {  
    public static void main(String[] args) { 
    new WebTest(); 
    } 
}