Java 错误NullPointerException:锁==null
有人能帮我解决这个错误吗?当我运行应用程序并搜索ID时,请选择MySQL数据库到Android的值,它总是说(无效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Java 错误NullPointerException:锁==null,java,android,Java,Android,有人能帮我解决这个错误吗?当我运行应用程序并搜索ID时,请选择MySQL数据库到Android的值,它总是说(无效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 savedInstanceSta
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<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
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());
}
}
感谢您的帮助
E/Fail 1(1073): android.os.NetworkOnMainThreadException
引发此错误的原因是您在主活动的线程上运行网络连接调用(如httpclient
)。为了摆脱这种情况,您需要为这些调用使用另一个线程。这样做的简单方法是使用
E/Fail 1(1073): android.os.NetworkOnMainThreadException