错误NullPointerException：lock == null

任何人都可以帮助我解决这个错误，当我运行应用程序并搜索ID时，从MySQL数据库选择值到Android，它总是说（无效的IP地址）…

我的Web服务器上有一个PHP文件，它连接到WampServer数据库并检索返回到Android应用程序的值。

String id String name; InputStream is=null; String result=null; String line; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); final EditText e_id=(EditText) findViewById(R.id.editText1); Button select=(Button) findViewById(R.id.button1); select.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // TODO Auto-generated method stub id=e_id.getText().toString(); select(); } }); } public void select() { ArrayList nameValuePairs = new ArrayList(); nameValuePairs.add(new BasicNameValuePair("id",id)); try { HttpClient httpclient = new DefaultHttpClient(); HttpPost httppost = new HttpPost("http://10.0.2.2/test/select.php"); httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs)); HttpResponse response = httpclient.execute(httppost); HttpEntity entity = response.getEntity(); is = entity.getContent(); Log.e("pass 1", "connection success "); } catch(Exception e) { Log.e("Fail 1", e.toString()); Toast.makeText(getApplicationContext(), "Invalid IP Address", Toast.LENGTH_LONG).show(); } try { BufferedReader reader = new BufferedReader (new InputStreamReader(is,"iso-8859-1"),8); StringBuilder sb = new StringBuilder(); while ((line = reader.readLine()) != null) { sb.append(line + "\n"); } is.close(); result = sb.toString(); Log.e("pass 2", "connection success "); } catch(Exception e) { Log.e("Fail 2", e.toString()); } try { JSONObject json_data = new JSONObject(result); name=(json_data.getString("name")); Toast.makeText(getBaseContext(), "Name : "+name, Toast.LENGTH_SHORT).show(); } catch(Exception e) { Log.e("Fail 3", e.toString()); } } 

LogCat错误：

 11-17 02:40:58.059: E/Fail 1(1073): android.os.NetworkOnMainThreadException 11-17 02:40:58.079: E/Fail 2(1073): java.lang.NullPointerException: lock == null 11-17 02:40:58.079: E/Fail 3(1073): java.lang.NullPointerException 

任何帮助表示…

Answer 1

 E/Fail 1(1073): android.os.NetworkOnMainThreadException 

引发此错误的原因是您在主Activity的线程上运行网络连接调用（如httpclient ）。 要摆脱这种情况，你需要使用另一个线程进行这些调用。 这样做的简单方法是使用异步任务