I'm developing a Carpool Android app and using Java Servlets and JDBC, the Login and Registration are working fine. After a Custemer login, a listView will be shown with the names and numbers of the drivers, but when i login, it crashs and i didn't understand why and the problem is not in the LoginActivity. the Java Servlet is Ok and the Database is Ok. This is My code :
CustomersActivity:
public class CustomerActivity extends AppCompatActivity {
private static ListView list_view;
private static ArrayList<String> ar_list;
private static String[] tabNum;
TextView txt;
String recieved;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_custemer);
list_view = (ListView)findViewById(R.id.list);
txt = (TextView)findViewById(R.id.txtHello);
Intent i = getIntent();
final String name = i.getStringExtra("name");
new Thread(new Runnable() {
@Override
public void run() {
try {
URL url = new URL("http://10.0.2.2:8081/MiniProjectAJ/CustomerServlet");
URLConnection cnx = url.openConnection();
cnx.setDoOutput(true);
OutputStreamWriter out = new OutputStreamWriter(cnx.getOutputStream());
out.write("Hello");
out.close();
BufferedReader bf = new BufferedReader(new InputStreamReader(cnx.getInputStream()));
String returnString = "";
recieved = "";
while ((returnString = bf.readLine()) != null) {
recieved = returnString;
}
String[] sp = recieved.split("\\/");
String one = sp[0];
int i = Integer.parseInt(one);
int p = 1;
tabNum = new String[i];
while (p <= i) {
String two = sp[p];
String[] s = two.split("-");
String t = s[1];
ar_list.add(two);
tabNum[p-1] = t;
p = p + 1;
}
bf.close();
runOnUiThread(new Runnable() {
@Override
public void run() {
txt.setText("Hello "+name);
ArrayAdapter adapter = new ArrayAdapter(CustemerActivity.this, android.R.layout.simple_spinner_dropdown_item, ar_list);
list_view.setAdapter(adapter);
}
});
}
catch (MalformedURLException e) {
e.printStackTrace();
}
catch (IOException e) {
e.printStackTrace();
}
}
}).start();
list_view.setOnItemClickListener(new AdapterView.OnItemClickListener() {
@Override
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
String num = tabNum[position];
Intent i2 = new Intent(Intent.ACTION_DIAL, Uri.parse("tel:"+num));
startActivity(i2);
}
});
}
}
CustomerServlet :
public class CustomerServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public CustomerServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
response.getWriter().append("Served at: ").append(request.getContextPath());
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
//doGet(request, response);
try {
int length = request.getContentLength();
byte[] input = new byte[length];
ServletInputStream sin = request.getInputStream();
int c, count = 0;
while ((c=sin.read(input, count, input.length-count))!=-1) {
count+=c;
}
sin.close();
String receivedString = new String(input);
System.out.println(receivedString);
response.setStatus(HttpServletResponse.SC_OK);
OutputStreamWriter writer = new OutputStreamWriter(response.getOutputStream());
Connection con = EtablirConnection.getConnection();
String Q = "SELECT FName,LName,Number FROM drivers;";
String Q2 = "SELECT COUNT(*) FROM drivers;";
Statement st = con.createStatement();
Statement st1 = con.createStatement();
ResultSet rsc = st1.executeQuery(Q2);
String send = "";
while (rsc.next()) {
send = rsc.getString(1);
}
ResultSet rs = st.executeQuery(Q);
while (rs.next()) {
String Name = rs.getString("FName")+" "+rs.getString("LName");
String Number = rs.getString("Number");
send = send+"/"+Name+"-"+Number;
}
System.out.println(send);
writer.write(send);
writer.flush();
writer.close();
} catch(IOException | SQLException e){
try {
response.setStatus(HttpServletResponse.SC_BAD_REQUEST);
response.getWriter().print(e.getMessage());
response.getWriter().close();
} catch (IOException ioe) {
}
}
}
}
Logs :
12-30 20:19:14.129 10056-10056/? I/art: Not late-enabling -Xcheck:jni (already on)
12-30 20:19:14.129 10056-10056/? W/art: Unexpected CPU variant for X86 using defaults: x86
12-30 20:19:14.333 10056-10056/apps.dev.ndroid.projectandroj2ee W/System: ClassLoader referenced unknown path: /data/app/apps.dev.ndroid.projectandroj2ee-1/lib/x86
12-30 20:19:14.393 10056-10056/apps.dev.ndroid.projectandroj2ee I/InstantRun: starting instant run server: is main process
12-30 20:19:14.545 10056-10056/apps.dev.ndroid.projectandroj2ee W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
12-30 20:19:14.828 10056-10085/apps.dev.ndroid.projectandroj2ee I/OpenGLRenderer: Initialized EGL, version 1.4
12-30 20:19:14.828 10056-10085/apps.dev.ndroid.projectandroj2ee D/OpenGLRenderer: Swap behavior 1
12-30 20:19:14.828 10056-10085/apps.dev.ndroid.projectandroj2ee W/OpenGLRenderer: Failed to choose config with EGL_SWAP_BEHAVIOR_PRESERVED, retrying without...
12-30 20:19:14.828 10056-10085/apps.dev.ndroid.projectandroj2ee D/OpenGLRenderer: Swap behavior 0
12-30 20:19:14.932 10056-10056/apps.dev.ndroid.projectandroj2ee W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
12-30 20:19:19.273 10056-10085/apps.dev.ndroid.projectandroj2ee D/OpenGLRenderer: endAllActiveAnimators on 0xaabb1180 (RippleDrawable) with handle 0x9a24d010
12-30 20:19:20.936 10056-10085/apps.dev.ndroid.projectandroj2ee D/OpenGLRenderer: endAllActiveAnimators on 0x9a2d1800 (RippleDrawable) with handle 0x9a24d020
12-30 20:19:35.058 10056-10056/apps.dev.ndroid.projectandroj2ee W/IInputConnectionWrapper: finishComposingText on inactive InputConnection
12-30 20:19:42.830 10056-10512/apps.dev.ndroid.projectandroj2ee D/NetworkSecurityConfig: No Network Security Config specified, using platform default
12-30 20:19:42.912 10056-10515/apps.dev.ndroid.projectandroj2ee E/AndroidRuntime: FATAL EXCEPTION: Thread-5
Process: apps.dev.ndroid.projectandroj2ee, PID: 10056
java.lang.NullPointerException: Attempt to invoke virtual method 'boolean java.util.ArrayList.add(java.lang.Object)' on a null object reference
at apps.dev.ndroid.projectandroj2ee.CustemerActivity$1.run(CustemerActivity.java:64)
at java.lang.Thread.run(Thread.java:761)
12-30 20:19:43.084 10056-10056/apps.dev.ndroid.projectandroj2ee W/IInputConnectionWrapper: finishComposingText on inactive InputConnection
12-30 20:19:43.295 10056-10085/apps.dev.ndroid.projectandroj2ee D/OpenGLRenderer: endAllActiveAnimators on 0x9a354800 (RippleDrawable) with handle 0x9a279290
