Java 发出post请求会引发nullpointerexception

我试图从我的一个android应用程序发出post请求，但由于某种原因，

HttpClient.execute

方法出错

在我的应用程序中，我有一个makePostRequest方法，用于发出post请求。方法如下：

// Makes a post request to the server
public void makePostRequest(String url, ArrayList<NameValuePair> postData) {
    HttpClient client = new DefaultHttpClient();
    HttpPost postRequest = new HttpPost();

    try {
        boolean prnull = postRequest == null;
        Log.d("DEBUG:", String.valueOf(prnull));
        postRequest.setEntity(new UrlEncodedFormEntity(postData));
        HttpResponse response = client.execute(postRequest);
        Log.i("INFO:", response.toString());
    } catch (ClientProtocolException e) {
        Log.d("DEBUG:", e.toString());
    } catch (IOException e) {
        Log.d("DEBUG:", e.toString());
    }

}

// Server url variables
public String base_url = "http://192.168.2.8:8000";
public String login_url = base_url + "/login/";
public String register_url = base_url + "/api/v1/users";

我已经检查了

postRequest

是否为null，因为这是传递给

execute

方法的唯一参数。这里可能出了什么问题

更新

URL被定义为

ShotsActivity

类中的字符串变量，该类

RegisterActivity

扩展了该类。URL的定义如下：

// Makes a post request to the server
public void makePostRequest(String url, ArrayList<NameValuePair> postData) {
    HttpClient client = new DefaultHttpClient();
    HttpPost postRequest = new HttpPost();

    try {
        boolean prnull = postRequest == null;
        Log.d("DEBUG:", String.valueOf(prnull));
        postRequest.setEntity(new UrlEncodedFormEntity(postData));
        HttpResponse response = client.execute(postRequest);
        Log.i("INFO:", response.toString());
    } catch (ClientProtocolException e) {
        Log.d("DEBUG:", e.toString());
    } catch (IOException e) {
        Log.d("DEBUG:", e.toString());
    }

}

// Server url variables
public String base_url = "http://192.168.2.8:8000";
public String login_url = base_url + "/login/";
public String register_url = base_url + "/api/v1/users";

---

我认为问题在于，尽管您将字符串url传递给makePostRequest（），但您不会在任何地方使用它。也许您应该将其传递到HttpPost（url）

您在哪里定义和使用url？我认为您应该将url传递到HttpPost@SaraSeppolaURL在类中定义为

String

变量，请参见更新。谢谢。您应该将url作为新的HttpPost（url）传递。没问题，从其他人那里更容易找到bug代码：-）