如果使用下面的代码,我不会有任何错误,但是会有冻结时间。
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
setContentView(R.layout.profilepic);
initialize();
Bundle bundle = getIntent().getExtras();
email = bundle.getString("Email");
ArrayList<NameValuePair> postParameters;
String response = null;
postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("emaillog", email));
try {
response = CustomHttpClient.executeHttpPost("http://whatstherex.info/checkU.php", postParameters);
res = response.toString();
res = res.replaceAll("null", "");
username = res.toString();
tvProfilePic.setText("Hi " + username + ", you are encourage to add a profile picture.");
}catch(Exception e){
res = e.toString();
tvProfilePic.setText(res);
}
}
但是如果我将此代码与asyncTask和progressDialog一起使用,如下所示:
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
setContentView(R.layout.profilepic);
initialize();
getUsername();
}
private AsyncTask<String, Void, String> task;
public void getUsername(){
Bundle bundle = getIntent().getExtras();
email = bundle.getString("Email");
task = new AsyncTask<String, Void, String>() {
ProgressDialog dialog;
ArrayList<NameValuePair> postParameters;
String response = null;
@Override
protected void onPreExecute() {
//
ArrayList<NameValuePair> postParameters = new ArrayList<NameValuePair>();
postParameters.add(new BasicNameValuePair("emaillog", email));
dialog = new ProgressDialog(Profilepic.this, ProgressDialog.STYLE_SPINNER);
dialog.setMessage("Loading Data...");
dialog.show();
}
@Override
protected String doInBackground(String... params) {
//
try {
response = CustomHttpClient.executeHttpPost("http://whatstherex.info/checkU.php", postParameters);
res = response.toString();
res = res.replaceAll("null", "");
username = res.toString();
return username;
}catch(Exception e){
res = e.toString();
return res;
}
}
@Override
protected void onPostExecute(String result) {
if(result.length()< 25){
username = result;
tvProfilePic.setText("Hi " + result + ", you are encourage to add a profile picture.");
dialog.dismiss();
}else{
tvProfilePic.setText(result);
dialog.dismiss();
}
}
};
task.execute();
}
我在文本视图中得到java.lang.NullPointerException
。
有什么问题?有人可以帮我解决NullPointerException
出现的问题吗?
[我看到您使用tvProfilePic,但看不到定义的位置。
如果您没有定义它,则应采用与]相似的方式进行>
tvProfilePic = findViewById(R.id.profile_pic)
您正在这样做吗?请注意,“ profile_pic”是布局XML文档中的名称。