Develop Reference

Why does the app displays nothing even though i have no running error?

I am trying to do a weather App and after I get the data and I try to display it, I also try to see it in Log because it displays nothing, but here it also shows nothing. I also have no errors in running.
This is the code:
package com.example.weatherapp;
import androidx.appcompat.app.AppCompatActivity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import org.json.JSONArray;
import org.json.JSONObject;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
public class MainActivity extends AppCompatActivity {
TextView cityName;
Button searchButton;
TextView result;
class Weather extends AsyncTask<String, Void, String>{
#Override
protected String doInBackground(String... adress) {
try {
URL url = new URL(adress[0]);
HttpURLConnection connection = (HttpURLConnection) url.openConnection();
connection.connect();
InputStream is = connection.getInputStream();
InputStreamReader isr = new InputStreamReader(is);
int data = isr.read();
String content = "";
char ch;
while (data != -1){
ch = (char) data;
content = content + ch;
data = isr.read();
}
return content;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
}
public void search (View view){
cityName = findViewById(R.id.cityName);
searchButton = findViewById(R.id.searchButton);
result = findViewById(R.id.result);
String cName = cityName.getText().toString();
String content;
Weather weather = new Weather();
try {
content = weather.execute("https://openweathermap.org/data/2.5/weather?q=" + cName + "&appid=439d4b804bc8187953eb36d2a8c26a02").get();
JSONObject jsonObject = new JSONObject(content);
String weatherData = jsonObject.getString("weather");
JSONArray array = new JSONArray(weatherData);
String main ="";
String description ="";
for (int i = 0; i<=array.length(); i++){
JSONObject weatherPart = array.getJSONObject(i);
main = weatherPart.getString("main");
description = weatherPart.getString("description");
}
Log.w("main", main);
Log.w("description", description);
result.setText("Main : "+ main + "\nDescription : "+ description);
} catch (Exception e) {
e.printStackTrace();
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
The searchButton onClickListener is implemented in XML, so it works, and here is what the log displays when I run the app:
2020-04-20 21:46:22.482 12518-12611/com.example.weatherapp D/NetworkSecurityConfig: No Network Security Config specified, using platform default
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: org.json.JSONException: Index 1 out of range [0..1)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at org.json.JSONArray.get(JSONArray.java:293)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at org.json.JSONArray.getJSONObject(JSONArray.java:521)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at com.example.weatherapp.MainActivity.search(MainActivity.java:88)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at java.lang.reflect.Method.invoke(Native Method)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:397)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.view.View.performClick(View.java:5610)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.view.View$PerformClick.run(View.java:22265)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.os.Handler.handleCallback(Handler.java:751)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.os.Handler.dispatchMessage(Handler.java:95)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.os.Looper.loop(Looper.java:154)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6077)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at java.lang.reflect.Method.invoke(Native Method)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
2020-04-20 21:46:22.896 12518-12518/com.example.weatherapp W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
I can't find any clue why this doesn't work. Can you help me?

Your for loop terminates at i <= array.length();, which results in the JSONException, as the loop goes over the array`s length.
As the first item in Java arrays is located on the zero-index, their last item is located at the index of array.length() - 1, so in your case, you should end your for loop at i < array.length();

File Writer Android

I am using the following code to write an onPostExecute process to file from my FileWriter.class, it was working fine but am updating my application and I have to use the Environment.getExternalStorageDirectory().getPath(); instead of this, i tried following. I know doing something slightly wrong. Any Help or direction would be helpful.
Thanks.
public class FileWriter {
public void appendData( String text) {
try {
File myFile = new File("/sdcard/latencyOP.csv");
// myFile.createNewFile();
FileOutputStream fOut = new FileOutputStream(myFile);
OutputStreamWriter myOutWriter =
new OutputStreamWriter(fOut);
if (myFile.createNewFile()) {
myOutWriter.append("TimeStamp,ExecutionTime,OperationType;");
}
myOutWriter.append(text);
myOutWriter.close();
fOut.close();
/**
* Toast.makeText(getBaseContext(),
* "Done writing SD 'mysdfile.txt'",
Toast.LENGTH_SHORT).show();
*/
} catch (Exception e) {
/**
* Toast.makeText(getBaseContext(), e.getMessage(),
* Toast.LENGTH_SHORT).show();
*/
}
}
}
EDIT
I forgot to add that I am attempting to do some background operations and publish results on the **FILE.csv** thread without having to manipulate threads.
UPDATED CODE #Leonardo Acevedo
try {
File myFile = new File(
Environment.getExternalStorageDirectory(),
"latencyOP.csv"
);
boolean needToCreateFile = !myFile.exists();
if (needToCreateFile) {
myFile.createNewFile();
}
FileOutputStream fOut = new FileOutputStream(myFile);
OutputStreamWriter myOutWriter =
new OutputStreamWriter(fOut);
// At this point your file is guaranteed to exist
if (needToCreateFile) {
myOutWriter.append("TimeStamp,ExecutionTime,OperationType;");
}
myOutWriter.append(text);
myOutWriter.close();
fOut.close();
Toast.makeText(getBaseContext(),
"Done writing SD 'mysdfile.txt'",
Toast.LENGTH_SHORT
).show();
} catch (Exception e) {
e.printStackTrace();
displayExceptionMessage(e.getMessage());
//Toast.makeText(this, e.getMessage(), Toast.LENGTH_SHORT).show();
}
}
public void displayExceptionMessage(String msg) {
//Toast.makeText(this, "Some Error Occured", Toast.LENGTH_SHORT).show();
}
ASYNCH TASK PROCESS
protected void onPreExecute(){ startTime = Calendar.getInstance().getTime().getTime();
}
protected void onPostExecute(Long result) {
endTime = Calendar.getInstance().getTime().getTime();
long timeDiff = endTime - startTime;
FileWriter fileWriter = new FileWriter();
String data = endTime + "," + timeDiff + "," + "Authentication" + ";";
fileWriter.appendData(data);
}
Is this wrong ?
03-14 20:42:52.062 17192-17192/com.demo.common.recordwritertest W/System.err: java.io.IOException: Permission denied
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at java.io.UnixFileSystem.createFileExclusively0(Native Method)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at java.io.UnixFileSystem.createFileExclusively(UnixFileSystem.java:280)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at java.io.File.createNewFile(File.java:948)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at com.demo.common.recordwritertest.utils.FileWriter.appendData(FileWriter.java:25)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at com.demo.common.recordwritertest.com.demo.common.recordwritertest.asynctasks.AuthenticationAsyncTask.onPostExecute(AuthenticationAsyncTask.java:119)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at com.demo.common.recordwritertest.com.demo.common.recordwritertest.asynctasks.AuthenticationAsyncTask.onPostExecute(AuthenticationAsyncTask.java:27)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.os.AsyncTask.finish(AsyncTask.java:667)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.os.AsyncTask.-wrap1(AsyncTask.java)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:684)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.os.Looper.loop(Looper.java:154)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at android.app.ActivityThread.main(ActivityThread.java:6119)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at java.lang.reflect.Method.invoke(Native Method)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
03-14 20:42:52.063 17192-17192/com.demo.common.recordwritertest W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)

Registration form android studio to connect to server

No errors occur within when emulator is run on my android phone. Not sure if that the correct http:192.168....... When I run the app i enter the data and it says connecting to server but then says unfortunately the app crashed. Any Ideas.
BackgroundTask
package com.example.om.fitnessproject;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.AsyncTask;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLEncoder;
public class BackgroundTask extends AsyncTask<String, Void, String > {
String register_url = "https://192.168.0.4/Fitnessplus/register.php";
Context ctx;
ProgressDialog progressDialog;
Activity activity;
AlertDialog.Builder builder;
public BackgroundTask(Context ctx){
this.ctx = ctx;
activity = (Activity)ctx;
}
#Override
protected void onPreExecute() {
builder = new AlertDialog.Builder(activity);
progressDialog = new ProgressDialog(ctx);
progressDialog.setTitle("Please wait");
progressDialog.setMessage("Connecting to server");
progressDialog.setIndeterminate(true);
progressDialog.setCancelable(false);
progressDialog.show();
}
#Override
protected String doInBackground(String... params) {
String method = params [0];
if(method.equals("register"))
{
try {
URL url = new URL(register_url);
HttpURLConnection httpURLConnection = (HttpURLConnection)url.openConnection();
httpURLConnection.setRequestMethod("POST");
httpURLConnection.setDoOutput(true);
httpURLConnection.setDoInput(true);
OutputStream outputStream = httpURLConnection.getOutputStream();
BufferedWriter bufferedWriter = new BufferedWriter(new OutputStreamWriter(outputStream,"UTF-8"));
String name = params[1];
String email = params[2];
String password = params[3];
String data = URLEncoder.encode("name","UTF- 8")+"="+URLEncoder.encode(name,"UTF-8")+"&"+
URLEncoder.encode("email","UTF-8")+"="+URLEncoder.encode(email, "UTF-8")+"&"+
URLEncoder.encode("password","UTF-8")+"="+URLEncoder.encode(password,"UTF-8");
bufferedWriter.write(data);
bufferedWriter.flush();
bufferedWriter.close();
outputStream.close();
InputStream inputStream = httpURLConnection.getInputStream();
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream));
StringBuilder stringBuilder = new StringBuilder();
String line = "";
while ((line=bufferedReader.readLine())!=null)
{
stringBuilder.append(line+"\n");
}
httpURLConnection.disconnect();
Thread.sleep(5000);
return stringBuilder.toString().trim();
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
return null;
}
#Override
protected void onProgressUpdate(Void... values) {
super.onProgressUpdate(values);
}
#Override
protected void onPostExecute(String json) {
try {
progressDialog.dismiss();
JSONObject jsonObject = new JSONObject(json);
JSONArray jsonArray = jsonObject.getJSONArray("server_response");
JSONObject JO = jsonArray.getJSONObject(0);
String code = JO.getString("code");
String message = JO.getString("message");
if (code.equals("reg_true"))
{
showDialog("Registration Success", message,code);
}
else if(code.equals("reg_false"))
{
showDialog("Registration failed", message, code);
}
} catch (JSONException e) {
e.printStackTrace();
}
}
public void showDialog(String title,String message,String code)
{
builder.setTitle(title);
if(code.equals("reg_true")||code.equals("reg_false"))
{
builder.setMessage(message);
builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
activity.finish();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
}
}
register
package com.example.om.fitnessproject;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class register extends AppCompatActivity {
EditText Name, Email, Pass, ConPass;
Button reg_button;
AlertDialog.Builder builder;
#Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_register);
Name = (EditText)findViewById(R.id.reg_name);
Email = (EditText)findViewById(R.id.reg_email);
Pass = (EditText)findViewById(R.id.reg_password);
ConPass = (EditText)findViewById(R.id.reg_con_password);
reg_button = (Button)findViewById(R.id.reg_button);
reg_button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (Name.getText().toString().equals("") || Email.getText().toString().equals("") || Pass.getText().toString().equals("")) {
builder = new AlertDialog.Builder(register.this);
builder.setTitle("Something went wrong");
builder.setMessage("Please fill in all the field");
builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
} else if (!(Pass.getText().toString().equals(ConPass.getText().toString()))) {
builder = new AlertDialog.Builder(register.this);
builder.setTitle("Something went wrong");
builder.setMessage("Your passwords are not matching");
builder.setPositiveButton("Ok", new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog, int which) {
dialog.dismiss();
Pass.setText("");
ConPass.setText("");
}
});
AlertDialog alertDialog = builder.create();
alertDialog.show();
}
else {
BackgroundTask backgroundTask = new BackgroundTask(register.this);
backgroundTask.execute("register",Name.getText().toString(),Email.getText().toString(),Pass.getText().toString());
}
}
});
}
}
Trace
04-18 20:42:35.360 26137-26137/? I/art: Late-enabling -Xcheck:jni
04-18 20:42:35.532 26137-26137/com.example.kieranbroom.fitnessproject W/System: ClassLoader referenced unknown path: /data/app/com.example.kieranbroom.fitnessproject-1/lib/arm64
04-18 20:42:36.458 26137-26209/com.example.kieranbroom.fitnessproject D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
04-18 20:42:36.520 26137-26209/com.example.kieranbroom.fitnessproject I/Adreno: QUALCOMM build : 63c06b2, I8366cd0437
Build Date : 10/21/15
OpenGL ES Shader Compiler Version: XE031.05.13.02
Local Branch :
Remote Branch : quic/LA.BF64.1.2.9_v2
Remote Branch : NONE
Reconstruct Branch : NOTHING
04-18 20:42:36.526 26137-26209/com.example.kieranbroom.fitnessproject I/OpenGLRenderer: Initialized EGL, version 1.4
04-18 20:42:59.950 26137-26209/com.example.kieranbroom.fitnessproject D/OpenGLRenderer: endAllStagingAnimators on 0x7f9623f800 (RippleDrawable) with handle 0x7f96234220
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: javax.net.ssl.SSLHandshakeException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImp l.java:328)
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.http.SocketConnector.connectTls(SocketConnector.java:103)
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.Connection.connect(Connection.java:143)
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.Connection.connectAndSetOwner(Connection.java:185)
04-18 20:43:05.999 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.OkHttpClient$1.connectAndSetOwner(OkHttpClient.java:128)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.http.HttpEngine.nextConnection(HttpEngine.java: 341)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:330)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:248)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:437)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.connect(HttpURLConnectionImpl.java:114)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.huc.HttpURLConnectionImpl.getOutputStream(HttpURLConnectionImpl.java:245)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.huc.DelegatingHttpsURLConnection.getOutputStream(DelegatingHttpsURLConnection.java:218)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.okhttp.internal.huc.HttpsURLConnectionImpl.getOutputStream(HttpsURLConnectionImpl.java)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.example.kieranbroom.fitnessproject.BackgroundTask.doInBackground(BackgroundTask.java:64)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.example.kieranbroom.fitnessproject.BackgroundTask.doInBackground(BackgroundTask.java:26)
04-18 20:43:06.000 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at android.os.AsyncTask$2.call(AsyncTask.java:295)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at java.util.concurrent.FutureTask.run(FutureTask.java:237)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at java.lang.Thread.run(Thread.java:818)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: Caused by: java.security.cert.CertificateException: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.TrustManagerImpl.checkTrusted(TrustManagerImpl.java:318)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.TrustManagerImpl.checkServerTrusted(TrustManagerImpl.java:219)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.Platform.checkServerTrusted(Platform.java:115)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.OpenSSLSocketImpl.verifyCertificateChain(OpenSSLSocketImpl.java:556)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.NativeCrypto.SSL_do_handshake(Native Method)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: at com.android.org.conscrypt.OpenSSLSocketImpl.startHandshake(OpenSSLSocketImpl.java:324)
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: ... 20 more
04-18 20:43:06.001 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: Caused by: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.
04-18 20:43:06.002 26137-26700/com.example.kieranbroom.fitnessproject W/System.err: ... 26 more
04-18 20:43:06.010 26137-26137/com.example.kieranbroom.fitnessproject D/AndroidRuntime: Shutting down VM
04-18 20:43:06.010 26137-26137/com.example.kieranbroom.fitnessproject E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.kieranbroom.fitnessproject, PID: 26137
java.lang.NullPointerException: Attempt to invoke virtual method 'int java.lang.String.length()' on a null object reference
at org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116)
at org.json.JSONTokener.nextValue(JSONTokener.java:94)
at org.json.JSONObject.<init>(JSONObject.java:156)
at org.json.JSONObject.<init>(JSONObject.java:173)
at com.example.kieranbroom.fitnessproject.BackgroundTask.onPostExecute(BackgroundTask.java:115)
at com.example.kieranbroom.fitnessproject.BackgroundTask.onPostExecute(BackgroundTask.java:26)
at android.os.AsyncTask.finish(AsyncTask.java:651)
at android.os.AsyncTask.-wrap1(AsyncTask.java)
at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:668)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)

Getting NetworkOnMainThreadException while implementing Runnable [duplicate]

This question already has answers here:
NetworkOnMainThreadException [duplicate]
(5 answers)
Closed 7 years ago.
I'm getting NetworkOnMainThreadException while using Runnable
Code:
public class FullscreenActivity extends AppCompatActivity {
public Socket socket;
public int SERVERPORT = 5000; /* port 5000 (for testing) */
public String SERVER_IP = "10.0.2.2"; /* local Android address of localhost */
ViewFlipper flipper;
ListView listing;
public void attemptConnect(View view) {
try {
EditText editTextAddress = (EditText) findViewById(R.id.address);
EditText editTextPort = (EditText) findViewById(R.id.port);
String SERVER_IP_loc = editTextAddress.getText().toString();
int SERVERPORT_loc = Integer.parseInt(editTextPort.getText().toString());
System.out.println("Attempt Connect: IP " + SERVER_IP_loc + " Port: " + SERVERPORT_loc);
System.out.println("SET");
ClientThread myClientTask = new ClientThread(SERVER_IP_loc, SERVERPORT_loc);
myClientTask.run();
System.out.println("CONNECTED");
flipper.setDisplayedChild(1);
} catch (Exception e) {
System.err.println(e.getMessage());
}
}
// Thinks the following is not a thread ??
class ClientThread implements Runnable {
ClientThread(String addr, int port) {
SERVER_IP = addr;
SERVERPORT = port;
}
public void run() {
try {
InetAddress serverAddr = InetAddress.getByName(SERVER_IP);
// gets to this line fine
socket = new Socket(serverAddr, SERVERPORT);
} catch (Exception e1) {
e1.printStackTrace();
}
}
}
}
My permissions are set up to allow internet access:
<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
I'm getting the following error:
6188-6188/test W/System.err: android.os.NetworkOnMainThreadException
6188-6188/test W/System.err: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1273)
6188-6188/test W/System.err: at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:110)
6188-6188/test W/System.err: at libcore.io.IoBridge.connectErrno(IoBridge.java:137)
6188-6188/test W/System.err: at libcore.io.IoBridge.connect(IoBridge.java:122)
6188-6188/test W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:183)
6188-6188/test W/System.err: at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:163)
6188-6188/test W/System.err: at java.net.Socket.startupSocket(Socket.java:592)
6188-6188/test W/System.err: at java.net.Socket.<init>(Socket.java:226)
6188-6188/test W/System.err: at test.FullscreenActivity$ClientThread.run(FullscreenActivity.java:363)
6188-6188/test W/System.err: at test(FullscreenActivity.java:340)
6188-6188/test W/System.err: at java.lang.reflect.Method.invoke(Native Method)
6188-6188/test W/System.err: at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(test:270)
6188-6188/test W/System.err: at android.view.View.performClick(View.java:5198)
6188-6188/test W/System.err: at android.view.View$PerformClick.run(View.java:21147)
6188-6188/test W/System.err: at android.os.Handler.handleCallback(Handler.java:739)
6188-6188/test W/System.err: at android.os.Handler.dispatchMessage(Handler.java:95)
6188-6188/test W/System.err: at android.os.Looper.loop(Looper.java:148)
6188-6188/test W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5417)
6188-6188/test W/System.err: at java.lang.reflect.Method.invoke(Native Method)
6188-6188/test W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
6188-6188/test W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
As far as I can tell, this should function as expected. It seems to think the Runnable isn't a thread, but I can't figure out why.

You need a Thread to run your Runnable for you. Simply calling run on a Runnable does not run it on a different thread.
new Thread(new ClientThread(SERVER_IP_loc, SERVERPORT_loc)).start();

RXJava Android - Network exception when trying to pull RSS feed

I currently am trying to pull down an RSS Feed as an XML file and I'm trying to use RXJava instead of an AsyncTask to parse and download the file.
I'm getting a network on the main thread error though while I'm trying to pull the feed down.
Here is the relevant code with observable which is in the main activity
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.rv_test_items);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
final ArrayList<TestItem> testItems = new ArrayList<>();
//testItems.add(new TestItem("Title here", "Content here"));
RssReader reader = new RssReader("http://www.feedforall.com/sample.xml");
// Subscribe on a new background thread, while returning the result on the UI thread.
// Using the RSS Classes we will pull the rss items from the rss feed and then create our
// own TestItem from them.
try {
Observable
.from(reader.getItems())
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1<RssItem>() {
#Override
public void call(RssItem item) {
TestItem newItem = new TestItem(item.getTitle(), item.getDescription());
testItems.add(newItem);
}
});
} catch (Exception e) {
e.printStackTrace();
Log.e("App", "Failed to download RSS Items");
}
TestItemAdapter testItemAdapter = new TestItemAdapter(testItems);
recyclerView.setLayoutManager(linearLayoutManager);
recyclerView.setAdapter(testItemAdapter);
And here is my RSSReader class
public class RssReader {
private String rssUrl;
public RssReader(String url) {
rssUrl = url;
}
public List<RssItem> getItems() throws Exception {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
//Creates a new RssHandler which will do all the parsing.
RssHandler handler = new RssHandler();
//Pass SaxParser the RssHandler that was created.
saxParser.parse(rssUrl, handler);
return handler.getRssItemList();
}
}
And my RSSHandler class
public class RssHandler extends DefaultHandler {
private List<RssItem> rssItemList;
private RssItem currentItem;
private boolean parsingTitle;
private boolean parsingLink;
private boolean parsingDescription;
public RssHandler() {
//Initializes a new ArrayList that will hold all the generated RSS items.
rssItemList = new ArrayList<RssItem>();
}
public List<RssItem> getRssItemList() {
return rssItemList;
}
//Called when an opening tag is reached, such as <item> or <title>
#Override
public void startElement(String uri, String localName, String qName, Attributes attributes) throws SAXException {
if (qName.equals("item"))
currentItem = new RssItem();
else if (qName.equals("title"))
parsingTitle = true;
else if (qName.equals("link"))
parsingLink = true;
else if (qName.equals("description"))
parsingDescription = true;
else if (qName.equals("media:thumbnail") || qName.equals("media:content") || qName.equals("image")) {
if (attributes.getValue("url") != null)
currentItem.setImageUrl(attributes.getValue("url"));
}
}
//Called when a closing tag is reached, such as </item> or </title>
#Override
public void endElement(String uri, String localName, String qName) throws SAXException {
if (qName.equals("item")) {
//End of an item so add the currentItem to the list of items.
rssItemList.add(currentItem);
currentItem = null;
} else if (qName.equals("title"))
parsingTitle = false;
else if (qName.equals("link"))
parsingLink = false;
else if (qName.equals("description"))
parsingDescription = false;
}
//Goes through character by character when parsing whats inside of a tag.
#Override
public void characters(char[] ch, int start, int length) throws SAXException {
if (currentItem != null) {
//If parsingTitle is true, then that means we are inside a <title> tag so the text is the title of an item.
if (parsingTitle)
currentItem.setTitle(new String(ch, start, length));
//If parsingLink is true, then that means we are inside a <link> tag so the text is the link of an item.
else if (parsingLink)
currentItem.setLink(new String(ch, start, length));
//If parsingDescription is true, then that means we are inside a <description> tag so the text is the description of an item.
else if (parsingDescription)
currentItem.setDescription(new String(ch, start, length));
}
}
}
Stack trace
10-07 11:39:15.040 1959-1959/? I/art: Late-enabling -Xcheck:jni
10-07 11:39:15.208 1959-1959/? W/System.err: java.io.IOException: Couldn't open http://www.feedforall.com/sample.xml
10-07 11:39:15.208 1959-1959/? W/System.err: at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:755)
10-07 11:39:15.208 1959-1959/? W/System.err: at org.apache.harmony.xml.ExpatReader.parse(ExpatReader.java:292)
10-07 11:39:15.208 1959-1959/? W/System.err: at javax.xml.parsers.SAXParser.parse(SAXParser.java:390)
10-07 11:39:15.208 1959-1959/? W/System.err: at javax.xml.parsers.SAXParser.parse(SAXParser.java:266)
10-07 11:39:15.208 1959-1959/? W/System.err: at com.polymorphicinc.retrofitsample.rss.RssReader.getItems(RssReader.java:36)
10-07 11:39:15.208 1959-1959/? W/System.err: at com.polymorphicinc.retrofitsample.ui.MainActivity.onCreate(MainActivity.java:47)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.Activity.performCreate(Activity.java:5990)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2278)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.ActivityThread.access$800(ActivityThread.java:151)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.os.Handler.dispatchMessage(Handler.java:102)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.os.Looper.loop(Looper.java:135)
10-07 11:39:15.208 1959-1959/? W/System.err: at android.app.ActivityThread.main(ActivityThread.java:5254)
10-07 11:39:15.208 1959-1959/? W/System.err: at java.lang.reflect.Method.invoke(Native Method)
10-07 11:39:15.209 1959-1959/? W/System.err: at java.lang.reflect.Method.invoke(Method.java:372)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698)
10-07 11:39:15.209 1959-1959/? W/System.err: Caused by: android.os.NetworkOnMainThreadException
10-07 11:39:15.209 1959-1959/? W/System.err: at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1147)
10-07 11:39:15.209 1959-1959/? W/System.err: at java.net.InetAddress.lookupHostByName(InetAddress.java:418)
10-07 11:39:15.209 1959-1959/? W/System.err: at java.net.InetAddress.getAllByNameImpl(InetAddress.java:252)
10-07 11:39:15.209 1959-1959/? W/System.err: at java.net.InetAddress.getAllByName(InetAddress.java:215)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.HostResolver$1.getAllByName(HostResolver.java:29)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.RouteSelector.resetNextInetSocketAddress(RouteSelector.java:232)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.RouteSelector.next(RouteSelector.java:124)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.HttpEngine.connect(HttpEngine.java:272)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.HttpEngine.sendRequest(HttpEngine.java:211)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.execute(HttpURLConnectionImpl.java:382)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.getResponse(HttpURLConnectionImpl.java:332)
10-07 11:39:15.209 1959-1959/? W/System.err: at com.android.okhttp.internal.http.HttpURLConnectionImpl.getInputStream(HttpURLConnectionImpl.java:199)
10-07 11:39:15.209 1959-1959/? W/System.err: at org.apache.harmony.xml.ExpatParser.openUrl(ExpatParser.java:753)
10-07 11:39:15.209 1959-1959/? W/System.err: ... 18 more
10-07 11:39:15.209 1959-1959/? E/App: Failed to download RSS Items
10-07 11:39:15.215 1959-1978/? D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
10-07 11:39:15.216 1959-1959/? D/: HostConnection::get() New Host Connection established 0xb42d9a00, tid 1959
10-07 11:39:15.219 1959-1959/? D/Atlas: Validating map...
10-07 11:39:15.281 1959-1978/? D/libEGL: loaded /system/lib/egl/libEGL_emulation.so
10-07 11:39:15.282 1959-1978/? D/libEGL: loaded /system/lib/egl/libGLESv1_CM_emulation.so
10-07 11:39:15.286 1959-1978/? D/libEGL: loaded /system/lib/egl/libGLESv2_emulation.so
10-07 11:39:15.295 1959-1978/? D/: HostConnection::get() New Host Connection established 0xb42d9b90, tid 1978
10-07 11:39:15.311 1959-1978/? I/OpenGLRenderer: Initialized EGL, version 1.4
10-07 11:39:15.360 1959-1978/? D/OpenGLRenderer: Enabling debug mode 0
10-07 11:39:15.381 1959-1978/? W/EGL_emulation: eglSurfaceAttrib not implemented
10-07 11:39:15.381 1959-1978/? W/OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xb424bb40, error=EGL_SUCCESS

Take a look at this to get an idea how to do it:
public class RssReader {
private String rssUrl;
public RssReader(String url) {
rssUrl = url;
}
public Observable<List<RssItem>> getItems() {
return Observable.create(new Observable.OnSubscribe<List<RssItem>>() {
#Override
public void call(Subscriber<? super List<RssItem>> subscriber) {
try {
SAXParserFactory factory = SAXParserFactory.newInstance();
SAXParser saxParser = factory.newSAXParser();
//Creates a new RssHandler which will do all the parsing.
RssHandler handler = new RssHandler();
//Pass SaxParser the RssHandler that was created.
saxParser.parse(rssUrl, handler);
subscriber.onNext(handler.getRssItemList());
subscriber.onCompleted();
} catch (Exception e) {
subscriber.onError(e);
}
}
});
}
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
recyclerView = (RecyclerView) findViewById(R.id.rv_test_items);
LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(linearLayoutManager);
RssReader reader = new RssReader("http://www.feedforall.com/sample.xml");
reader.getItems()
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1<List<RssItem>>() {
#Override
public void call(List<RssItem> items) {
final ArrayList<TestItem> testItems = new ArrayList<>(items.size());
for (int size = items.size(), i = 0; i < size; i++) {
RssItem item = items.get(i);
testItems.add(new TestItem(item.getTitle(), item.getDescription()));
}
recyclerView.setAdapter(new TestItemAdapter(testItems));
}
}, new Action1<Throwable>() {
#Override
public void call(Throwable e) {
e.printStackTrace();
Log.e("App", "Failed to download RSS Items");
}
});
}

try this
Observable.defer(() -> Observable.from(reader.getItems())
.subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(new Action1<RssItem>() {
#Override
public void call(RssItem item) {
TestItem newItem = new TestItem(item.getTitle(), item.getDescription());
testItems.add(newItem);
}
});