Android 代码在onPostExecute函数中不起作用
Android 代码在onPostExecute函数中不起作用,android,android-asynctask,Android,Android Asynctask,onPostExecute功能有问题。它没有调用函数,因为即使只调用了setText(“某物”)函数,也无法打印任何内容。请帮忙 public class Update extends Activity { JSONArray jArray = null; String result = null; StringBuilder sb = null; InputStream is = null; String ct_name; LinearLayo
onPostExecute
功能有问题。它没有调用函数,因为即使只调用了setText(“某物”)
函数,也无法打印任何内容。请帮忙
public class Update extends Activity {
JSONArray jArray = null;
String result = null;
StringBuilder sb = null;
InputStream is = null;
String ct_name;
LinearLayout l;
String responseString;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_update);
Toast.makeText(getBaseContext(), "Done layout", Toast.LENGTH_LONG)
.show();
new LongOperation().execute();
}
class LongOperation extends AsyncTask<String, String, String> {
@Override
protected String doInBackground(String... params) {
// http post
HttpClient httpclient = new DefaultHttpClient();
// Why to use 10.0.2.2
HttpPost httppost = new HttpPost(
"http://10.0.2.2/moodle/myFile.php");
try {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
response.getStatusLine().getStatusCode();
HttpEntity getResponseEntity = response.getEntity();
responseString = EntityUtils.toString(getResponseEntity);
} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
} catch (IOException e) {
// TODO Auto-generated catch block
}
return responseString;
}
protected void onPostExecute(String resultStr) {
try {
JSONObject json = new JSONObject(responseString);
JSONArray jArray = json.getJSONArray("result");
l = (LinearLayout) findViewById(R.id.container);
for (int i = 0; i < jArray.length(); i++) {
JSONObject json_data = jArray.getJSONObject(i);
ct_name = json_data.getString("name");
}
TextView txt = (TextView) findViewById(R.id.txt_1);
txt.setText("Executed");
Toast.makeText(getBaseContext(), "this is post",
Toast.LENGTH_LONG).show();
Toast.makeText(getBaseContext(), ct_name, Toast.LENGTH_LONG)
.show();
TextView textView = new TextView(null);
textView.setText(ct_name
+ " is out, please attempt it as soon as possible"
+ "\n");
l.addView(textView);
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
}
公共类更新扩展活动{
JSONArray-jArray=null;
字符串结果=null;
StringBuilder sb=null;
InputStream=null;
字符串ct_名称;
线性布局;
弦乐;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity\u更新);
Toast.makeText(getBaseContext(),“完成布局”,Toast.LENGTH\u LONG)
.show();
新的长操作().execute();
}
类LongOperation扩展了异步任务{
@凌驾
受保护的字符串doInBackground(字符串…参数){
//http post
HttpClient HttpClient=新的DefaultHttpClient();
//为什么要使用10.0.2.2
HttpPost HttpPost=新的HttpPost(
"http://10.0.2.2/moodle/myFile.php");
试一试{
ArrayList nameValuePairs=新的ArrayList();
setEntity(新的UrlEncodedFormEntity(nameValuePairs));
HttpResponse response=httpclient.execute(httppost);
response.getStatusLine().getStatusCode();
HttpEntity getResponseEntity=response.getEntity();
responseString=EntityUtils.toString(getResponseEntity);
}捕获(客户端协议例外e){
//TODO自动生成的捕捉块
}捕获(IOE异常){
//TODO自动生成的捕捉块
}
回报率;
}
受保护的void onPostExecute(字符串resultStr){
试一试{
JSONObject json=新的JSONObject(responseString);
JSONArray jArray=json.getJSONArray(“结果”);
l=(线性布局)findViewById(R.id.container);
for(int i=0;i
这是异步任务之前的工作代码
public class MainActivity extends Activity {
JSONArray jArray = null;
String result = null;
StringBuilder sb = null;
InputStream is = null;
String ct_name;
LinearLayout l;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
//http post
try{
HttpClient httpclient = new DefaultHttpClient();
//Why to use 10.0.2.2
HttpPost httppost = new HttpPost("http://10.0.2.2/moodle/myFile.php");
httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
HttpResponse response = httpclient.execute(httppost);
HttpEntity entity = response.getEntity();
is = entity.getContent();
}catch(Exception e){
Log.e("log_tag", "Error in http connection"+e.toString());
}
//convert response to string
try{
BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
sb = new StringBuilder();
sb.append(reader.readLine() + "\n");
String line="0";
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
result=sb.toString();
}catch(Exception e){
Log.e("log_tag", "Error converting result "+e.toString());
}
try{
jArray = new JSONArray(result);
JSONObject json_data=null;
l = (LinearLayout) findViewById(R.id.container);
for(int i=0;i<jArray.length();i++){
json_data = jArray.getJSONObject(i);
ct_name=json_data.getString("name");//here "Name" is the column name in database
Toast.makeText(getBaseContext(), ct_name,
Toast.LENGTH_LONG).show();
TextView textView = new TextView(this);
textView.setText(ct_name + " is out, please attempt it as soon as possible"+ "\n");
l.addView(textView);
}
}
catch(JSONException e1){
Toast.makeText(getBaseContext(), "No Data Found" ,Toast.LENGTH_LONG).show();
} catch (ParseException e1) {
e1.printStackTrace();
}
}
}
公共类MainActivity扩展活动{
JSONArray-jArray=null;
字符串结果=null;
StringBuilder sb=null;
InputStream=null;
字符串ct_名称;
线性布局;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList nameValuePairs=新的ArrayList();
//http post
试一试{
HttpClient HttpClient=新的DefaultHttpClient();
//为什么要使用10.0.2.2
HttpPost HttpPost=新的HttpPost(“http://10.0.2.2/moodle/myFile.php");
setEntity(新的UrlEncodedFormEntity(nameValuePairs));
HttpResponse response=httpclient.execute(httppost);
HttpEntity=response.getEntity();
is=entity.getContent();
}捕获(例外e){
e(“Log_标记”,“http连接错误”+e.toString());
}
//将响应转换为字符串
试一试{
BufferedReader reader=新的BufferedReader(新的InputStreamReader(is,“iso-8859-1”),8;
sb=新的StringBuilder();
sb.append(reader.readLine()+“\n”);
字符串行=“0”;
而((line=reader.readLine())!=null){
sb.追加(第+行“\n”);
}
is.close();
结果=sb.toString();
}捕获(例外e){
Log.e(“Log_标记”,“错误转换结果”+e.toString());
}
试一试{
jArray=新的JSONArray(结果);
JSONObject json_data=null;
l=(线性布局)findViewById(R.id.container);
对于此块最后一行中的(int i=0;i,应使用resultStr not responseString。
您也没有在doInBackground
方法中记录大多数异常。
养成使用Log.e(标记“错误描述…”,异常)
而不是使用e.printstackTrace()
或e.toString()
你能试着把@Override
放在onPostExecute
method@Override受保护的void onPostExecute(String resultStr){TextView TextView=new TextView(null);TextView.setText(“ct_name”)}我完成了此操作。它也无法显示任何内容
protected void onPostExecute(String resultStr) {
try {
JSONObject json = new JSONObject(responseString);