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Android- Null pointer exception from getStringExtra using intent send a value to another activity by button click

I am facing the problem when I use Intent to send a value to another activity by click a button. I have tried to solve it in many ways but it always show NullPointerException although I declared it clearly.
Here is my code.
Manufacturer.java
package com.example.student.macheckcar;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
public class Manufacturer extends AppCompatActivity {
public String message;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_manufacturer);
Button toyota = (Button) findViewById(R.id.Toyota);
Button subaru = (Button) findViewById(R.id.Subaru);
Button audi = (Button) findViewById(R.id.Audi);
toyota.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
message = "Toyota";
goAnother(message.toString());
}
});
subaru.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
message = "Subaru";
goAnother(message);
}
});
audi.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
message = "Audi";
goAnother(message);
}
});
}
protected void goAnother(String brand){
Intent i = new Intent(Manufacturer.this, ShowCarPrice.class);
i.putExtra("brand", brand);
startActivity(i);
}
}
Showcarprice.java
package com.example.student.macheckcar;
import android.content.Intent;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.view.Window;
import java.util.ArrayList;
public class ShowCarPrice extends AppCompatActivity {
private Cursor cursor;
private ArrayList<String> price;
private ArrayAdapter<String> aa;
private DBprice dbPrice;
private Manufacturer maFact;
SQLiteDatabase db;
ListView list;
Intent intent = getIntent();
String brand = intent.getStringExtra("brand");
#Override
protected void onCreate(Bundle savedInstanceState) {
requestWindowFeature(Window.FEATURE_NO_TITLE);
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_show_car_price);
list = (ListView) findViewById(R.id.listView);
dbPrice = new DBprice(this);
db = dbPrice.getWritableDatabase();
cursor = db.rawQuery("SELECT " + dbPrice.KEY_TASK + " FROM " + dbPrice.TABLE_NAME + " WHERE Manufacturer = ?", new String[] {brand});
price = new ArrayList<String>();
cursor.moveToFirst();
while ( !cursor.isAfterLast() ){
price.add(cursor.getString(cursor.getColumnIndex(dbPrice.KEY_TASK)));
cursor.moveToNext();
}
aa = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, price);
list.setAdapter(aa);
}
public void onPause() {
super.onPause();
dbPrice.close();
db.close();
}
}
And the error:
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.student.macheckcar, PID: 934
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.student.macheckcar/com.example.student.macheckcar.ShowCarPrice}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2110)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)
at android.app.ActivityThread.access$800(ActivityThread.java:135)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.student.macheckcar.ShowCarPrice.<init>(ShowCarPrice.java:22)
at java.lang.Class.newInstanceImpl(Native Method)
at java.lang.Class.newInstance(Class.java:1208)
at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2101)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233) 
at android.app.ActivityThread.access$800(ActivityThread.java:135) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:136) 
at android.app.ActivityThread.main(ActivityThread.java:5001) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:515) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
at dalvik.system.NativeStart.main(Native Method) 
Please help.

UPDATE
public class ShowCarPrice extends AppCompatActivity {
// OK, Create the objects, variables here if needed
Intent intent;
String brand;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.your_activity_layout);
// You should assign the intent here (in onCreate method)
intent = getIntent();
// Then, the string variable
brand = intent.getStringExtra("brand");
// You can also check whether or not received a valid value
if (brand != null && !brand.isEmpty())
// do something with brand value
else
// brand value is null or empty
}
}

Well, you call getIntent() at the wrong position. You should call getIntent() in method onCreate() , and I don't know why you keep intent as a member of your activity. If I were you I just do
String brand = getIntent().getStringExtra("brand");
in onCreate() method.

get your intent and extras of intent in onCreate() method of activity just check below link for this
https://stackoverflow.com/a/5265952/5316836

setOnItemSelectedListener makes my app crash

I am trying to use a Spinner to select a user name and then open a new conversation layout when the client clicks the start chat button. I am sure that the button code is correct but my spinner cause my application crash.
myListView.setOnItemSelectedListener(new OnItemSelectedListener () {
#Override
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
// An item was selected. You can retrieve the selected item using
name1 = parent.getItemAtPosition(pos).toString();
CStart = (Button) findViewById(R.id.Start) ;
CStart.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
open(v);
}
});
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
}
});
The open method:
protected void open(View v) {
Intent i = new Intent(this, MainActivity2.class);
i.putExtra("message", name1);
startActivityForResult(i, 1);
}
Can you help me to fix my code?
Logcat :
03-24 19:48:32.967: E/AndroidRuntime(23058): FATAL EXCEPTION: main
03-24 19:48:32.967: E/AndroidRuntime(23058): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.javachat/com.example.javachat.MainActivity}: java.lang.IllegalArgumentException: Receiver not registered: com.example.javachat.MainActivity$1#418afa30
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread.access$600(ActivityThread.java:162)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.os.Handler.dispatchMessage(Handler.java:107)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.os.Looper.loop(Looper.java:194)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread.main(ActivityThread.java:5371)
03-24 19:48:32.967: E/AndroidRuntime(23058):at java.lang.reflect.Method.invokeNative(Native Method)
03-24 19:48:32.967: E/AndroidRuntime(23058):at java.lang.reflect.Method.invoke(Method.java:525)
03-24 19:48:32.967: E/AndroidRuntime(23058):at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 03-24 19:48:32.967: E/AndroidRuntime(23058):at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
03-24 19:48:32.967: E/AndroidRuntime(23058):at dalvik.system.NativeStart.main(Native Method)
03-24 19:48:32.967: E/AndroidRuntime(23058): Caused by: java.lang.IllegalArgumentException: Receiver not registered: com.example.javachat.MainActivity$1#418afa30
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.LoadedApk.forgetReceiverDispatcher(LoadedApk.java:657)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ContextImpl.unregisterReceiver(ContextImpl.java:1442)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:445) 03-24 19:48:32.967: E/AndroidRuntime(23058): at com.example.javachat.MainActivity.onDestroy(MainActivity.java:229)
03-24 19:48:32.967: E/AndroidRuntime(23058):at com.example.javachat.MainActivity.onCreate(MainActivity.java:136)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.Activity.performCreate(Activity.java:5122)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1084)
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
03-24 19:48:32.967: E/AndroidRuntime(23058):... 11 more
manifest code :
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.javachat"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="19" />
<uses-permission android:name="android.permission.BLUETOOTH"/>
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity android:name=".MainActivity2" />
</application>
</manifest>
my .java file if you need to check any thing else like imports and methods....
package com.example.javachat;
import java.util.Set;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity {
private static final int REQUEST_ENABLE_BT = 1;
private Button onBtn;
private Button offBtn;
private Button listBtn;
private Button findBtn;
private TextView text;
private Button CStart ;
private String name1 ;
private BluetoothAdapter myBluetoothAdapter;
private Set<BluetoothDevice> pairedDevices;
private Spinner myListView;
private ArrayAdapter<String> BTArrayAdapter;
//*******************************MAIN************************
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main2);
// take an instance of BluetoothAdapter - Bluetooth radio
myBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
if(myBluetoothAdapter == null) {
onBtn.setEnabled(false);
offBtn.setEnabled(false);
listBtn.setEnabled(false);
findBtn.setEnabled(false);
CStart.setEnabled(false);
text.setText("Status: not supported");
Toast.makeText(getApplicationContext(),"Your device does not support Bluetooth",
Toast.LENGTH_LONG).show();
} else {
text = (TextView) findViewById(R.id.text);
onBtn = (Button)findViewById(R.id.turnOn);
onBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
on(v);
}
});
offBtn = (Button)findViewById(R.id.turnOff);
offBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
off(v);
}
});
//*********************************************************
listBtn = (Button)findViewById(R.id.paired);
listBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
list(v);
}
});
//**********************************************************
myListView.setOnItemSelectedListener(new OnItemSelectedListener (){
#Override
public void onItemSelected(AdapterView<?> parent, View view,
int pos, long id) {
// An item was selected. You can retrieve the selected item using
name1= new String (parent.getItemAtPosition(pos).toString());
CStart = (Button) findViewById(R.id.Start) ;
CStart.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
open(v);
}
});
}
public void onNothingSelected(AdapterView<?> parent) {
// Another interface callback
Toast.makeText(getApplicationContext(),"Select a device" ,
Toast.LENGTH_LONG).show();
}
});
//***********************************************************
findBtn = (Button)findViewById(R.id.search);
findBtn.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
find(v);
}
});
//***********************************************************
myListView = (Spinner)findViewById(R.id.listView1);
// create the arrayAdapter that contains the BTDevices, and set it to the ListView
BTArrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item);
BTArrayAdapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
myListView.setAdapter(BTArrayAdapter);
}
}
//**********************************METHODE***********************
protected void open(View v) {
// TODO Auto-generated method stub
Intent i = new Intent(this ,MainActivity2.class);
// i.putExtra("message",name1);
startActivityForResult(i, 1);
}
public void on(View view){
if (!myBluetoothAdapter.isEnabled()) {
Intent turnOnIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(turnOnIntent, REQUEST_ENABLE_BT);
Toast.makeText(getApplicationContext(),"Bluetooth turned on" ,
Toast.LENGTH_LONG).show();
}
else{
Toast.makeText(getApplicationContext(),"Bluetooth is already on",
Toast.LENGTH_LONG).show();
}
}
#Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
if(requestCode == REQUEST_ENABLE_BT){
if(myBluetoothAdapter.isEnabled()) {
text.setText("Status: Enabled");
} else {
text.setText("Status: Disabled");
}
}
}
public void list(View view){
// get paired devices
pairedDevices = myBluetoothAdapter.getBondedDevices();
// put it's one to the adapter
for(BluetoothDevice device : pairedDevices)
BTArrayAdapter.add(device.getName()+ "\n" + device.getAddress());
Toast.makeText(getApplicationContext(),"Show Paired Devices",
Toast.LENGTH_SHORT).show();
}
final BroadcastReceiver bReceiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// add the name and the MAC address of the object to the arrayAdapter
BTArrayAdapter.add(device.getName() + "\n" + device.getAddress());
BTArrayAdapter.notifyDataSetChanged();
}
}
};
public void find(View view) {
if (myBluetoothAdapter.isDiscovering()) {
// the button is pressed when it discovers, so cancel the discovery
myBluetoothAdapter.cancelDiscovery();
}
else {
BTArrayAdapter.clear();
myBluetoothAdapter.startDiscovery();
registerReceiver(bReceiver, new IntentFilter(BluetoothDevice.ACTION_FOUND));
}
}
public void off(View view){
myBluetoothAdapter.disable();
text.setText("Status: Disconnected");
Toast.makeText(getApplicationContext(),"Bluetooth turned off",
Toast.LENGTH_LONG).show();
}
#Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(bReceiver);
}
}

Exception clearly states the following:
Receiver not registered: com.example.javachat.MainActivity$1#418afa30
Crash happens here:
03-24 19:48:32.967: E/AndroidRuntime(23058):at android.content.ContextWrapper.unregisterReceiver(ContextWrapper.java:445)
03-24 19:48:32.967: E/AndroidRuntime(23058): at com.example.javachat.MainActivity.onDestroy(MainActivity.java:229)
03-24 19:48:32.967: E/AndroidRuntime(23058):at com.example.javachat.MainActivity.onCreate(MainActivity.java:136)
You have unregisterReceiver at the onDestroy, but you have no place, where you are registering it. Also you would like to take a look here, because onItemSelected will be called for Spinner without user action.
But it is not the end. The BroadcastReceiver declaration is wrong. Since you are using broadcast receiver locally, binding it to the Activity lifecycle, you should use LocalBroadcastManager, to register/unregister at the onCreate/onDestroy (or other lifecycle callbacks, depends on your needs). Thus, the following declaration in manifest makes no sense:
<receiver android:name=".bReceiver">
</receiver>
Because you have no class called bReceiver, you have a local variable (which should be actually made a class member) bReceiver, which points to an instance of BroadcastReceiver class.

if clicking on the Button is causing your crash, then the reason is -
you have set a method local anonymous inner class object as listener in your onItemSlected(). that object will be destroyed when the method execution is finished.
So when the onItemSelected is finished, your listener object is set properly. but by the time when button is being clicked, that saved listener object is invoked which is actually cleared by garbage collector.
you shouldn't set the listener this way. you can easily set the listener outside of your item click listener if I did understand your requirement correctly.

android app crashes when killing one activity and start another one

There is one button I set in Scene2.java.I want to use the button to get in other activities Scene3.java,GameOver.java Everything worked fine until its about to open the new activity,every time the app crashed there. I want to know if there're any mistake I made in the connection,which I mean the newIntent and getIntent inScene2.java GameOver.javaand Scene3.java
Scene2.java
package com.group5.littlered;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.graphics.drawable.ColorDrawable;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;
public class Scene2 extends Activity {
MediaPlayer bird;
MediaPlayer bgm;
int position = 0;
String[] conversation;
TextView frame;
ImageView conframe;
final String[] ListStr = { "Wake up and ask her", "Peek her secretly" };
int plot = 0;
#Override
public void onBackPressed() {
}
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
// Remove title bar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
// Remove notification bar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_scene2);
Intent intent1 = getIntent();
conversation = getResources().getStringArray(R.array.scene2);
frame = (TextView) findViewById(R.id.textView1);
Button next = (Button) findViewById(R.id.wtf);
next.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (position < 2) {
String sentence = conversation[position];
frame.setText(sentence + "");
position++;
} else {
if (plot < 1) {
AlertDialog choice = new AlertDialog.Builder(
Scene2.this).create();
choice.setTitle("Pick a choice");
choice.setMessage(" ");
choice.setButton("Get up and ask her what happened",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub
plot = 1;
}
});
choice.setButton2("Peek her secretly",
new DialogInterface.OnClickListener() {
#Override
public void onClick(DialogInterface dialog,
int which) {
// TODO Auto-generated method stub
plot = 2;
position = 4;
}
});
choice.show();
} else {
if (plot < 2) {
if (position < 4) {
String sentence = conversation[position];
frame.setText(sentence + "");
position++;
} else {
Intent intent2 = new Intent(Scene2.this,
GameOver.class);
startActivity(intent2);
finish();
}
} else {
if (position < 6) {
String sentence = conversation[position];
frame.setText(sentence + "");
position++;
} else {
Intent intent3 = new Intent(Scene2.this,
Scene3.class);
startActivity(intent3);
finish();
}
}
}
}
}
});
// BGM
bgm = MediaPlayer.create(Scene2.this, R.raw.voyager);
bgm.setLooping(true);
bgm.start();
// bird
bird = MediaPlayer.create(Scene2.this, R.raw.bird);
bird.setLooping(false);
bird.start();
}
}
Scene3.java
package com.group5.littlered;
import android.app.Activity;
import android.content.Intent;
import android.media.MediaPlayer;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;
public class Scene3 extends Activity {
int position = 0;
String[] conversation;
TextView frame;
ImageView conframe;
#Override
public void onBackPressed() {
}
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
// Remove title bar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
// Remove notification bar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_scene3);
Intent intent3 = getIntent();
conversation = getResources().getStringArray(R.array.scene1);
frame = (TextView) findViewById(R.id.textView1);
Button next = (Button) findViewById(R.id.wtf);
next.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
if (position < 6) {
String sentence = conversation[position];
frame.setText(sentence + "");
position++;
} else {
{
}
}
}
});
}
}
Again sorry for my poor ENGLISH, plz tell me what I need to post more to help you understand my problem.
my logcat
04-30 09:37:39.497: E/AndroidRuntime(4862): FATAL EXCEPTION: main
04-30 09:37:39.497: E/AndroidRuntime(4862): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.group5.littlered/com.group5.littlered.Scene3}: java.lang.NullPointerException
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2211)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread.access$600(ActivityThread.java:141)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.os.Handler.dispatchMessage(Handler.java:99)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.os.Looper.loop(Looper.java:137)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread.main(ActivityThread.java:5103)
04-30 09:37:39.497: E/AndroidRuntime(4862): at java.lang.reflect.Method.invokeNative(Native Method)
04-30 09:37:39.497: E/AndroidRuntime(4862): at java.lang.reflect.Method.invoke(Method.java:525)
04-30 09:37:39.497: E/AndroidRuntime(4862): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
04-30 09:37:39.497: E/AndroidRuntime(4862): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
04-30 09:37:39.497: E/AndroidRuntime(4862): at dalvik.system.NativeStart.main(Native Method)
04-30 09:37:39.497: E/AndroidRuntime(4862): Caused by: java.lang.NullPointerException
04-30 09:37:39.497: E/AndroidRuntime(4862): at com.group5.littlered.Scene3.onCreate(Scene3.java:45)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.Activity.performCreate(Activity.java:5133)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
04-30 09:37:39.497: E/AndroidRuntime(4862): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2175)
04-30 09:37:39.497: E/AndroidRuntime(4862): ... 11 more

The line that is crashing is the line 45 of Scene3:
Button next = (Button) findViewById(R.id.wtf);
next.setOnClickListener(new View.OnClickListener() { // <-- THIS ONE
...
});
The cause is a NullPointerException. This means that the identifier "wtf" exists in R (this wouldn't compile otherwise) but is not found in the layer activity_scene3, as we wave the following statement line 38 of Scene3.onCreate():
setContentView(R.layout.activity_scene3); // and later on findViewById() returns `null`
You have to revisit this layout to ensure that the Button you are willing to access to actually exists, with the ID wtf.
Generally speaking, this is the danger in using a same ID in different layouts. This is prone to hide errors that would easily be found otherwise as this would just not compile.

Check your manifest file and add Scene3.java in it
<activity
android:name=".Scene3" >
</activity>

Always post question with exception, second this is may be you have not mention your other activity in manifest file like:
<activity
android:name=".Scene3">
</activity>
<activity
android:name=".GameOver">
</activity>

NetworkOnMainThreadException error occurs when I change the minSDKVersion

I have developed a login and registrartion system and the code works fine when the minSDKVersion is set to 8,But when I change the minSDkVersion to higher versions say 11 or 12 the app crashes when I try to login or register.What changes should I make in the code so that i can run in higher versions.The LoginActivity.java file is as follows:
package com.example.trial;
import java.util.HashMap;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import com.example.trial.library.DatabaseHandler;
import com.example.trial.library.UserFunctions;
public class LoginActivity extends Activity {
Button btnLogin;
Button btnLinkToRegister;
EditText inputEmail;
EditText inputPassword;
TextView loginErrorMsg;
// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
// Importing all assets like buttons, text fields
inputEmail = (EditText) findViewById(R.id.loginEmail);
inputPassword = (EditText) findViewById(R.id.loginPassword);
btnLogin = (Button) findViewById(R.id.btnLogin);
btnLinkToRegister = (Button) findViewById(R.id.btnLinkToRegisterScreen);
loginErrorMsg = (TextView) findViewById(R.id.login_error);
// Login button Click Event
btnLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
UserFunctions userFunction = new UserFunctions();
Log.d("Button", "Login");
JSONObject json = userFunction.loginUser(email, password);
// check for login response
try {
if (json.getString(KEY_SUCCESS) != null) {
loginErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
// user successfully logged in
// Store user details in SQLite Database
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
// Clear all previous data in database
userFunction.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));
// Launch Dashboard Screen
Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
// Close all views before launching Dashboard
dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(dashboard);
// Close Login Screen
finish();
}else{
// Error in login
loginErrorMsg.setText("Incorrect username/password");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
// Link to Register Screen
btnLinkToRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
RegisterActivity.class);
startActivity(i);
finish();
}
});
}
}
The RegisterActivity.java file is:
package com.example.trial;
import org.json.JSONException;
import org.json.JSONObject;
import com.example.trial.library.DatabaseHandler;
import com.example.trial.library.UserFunctions;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class RegisterActivity extends Activity {
Button btnRegister;
Button btnLinkToLogin;
EditText inputFullName;
EditText inputEmail;
EditText inputPassword;
TextView registerErrorMsg;
// JSON Response node names
private static String KEY_SUCCESS = "success";
private static String KEY_ERROR = "error";
private static String KEY_ERROR_MSG = "error_msg";
private static String KEY_UID = "uid";
private static String KEY_NAME = "name";
private static String KEY_EMAIL = "email";
private static String KEY_CREATED_AT = "created_at";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.register);
// Importing all assets like buttons, text fields
inputFullName = (EditText) findViewById(R.id.registerName);
inputEmail = (EditText) findViewById(R.id.registerEmail);
inputPassword = (EditText) findViewById(R.id.registerPassword);
btnRegister = (Button) findViewById(R.id.btnRegister);
btnLinkToLogin = (Button) findViewById(R.id.btnLinkToLoginScreen);
registerErrorMsg = (TextView) findViewById(R.id.register_error);
// Register Button Click event
btnRegister.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
String name = inputFullName.getText().toString();
String email = inputEmail.getText().toString();
String password = inputPassword.getText().toString();
UserFunctions userFunction = new UserFunctions();
JSONObject json = userFunction.registerUser(name, email, password);
// check for login response
try {
if (json.getString(KEY_SUCCESS) != null) {
registerErrorMsg.setText("");
String res = json.getString(KEY_SUCCESS);
if(Integer.parseInt(res) == 1){
// user successfully registred
// Store user details in SQLite Database
DatabaseHandler db = new DatabaseHandler(getApplicationContext());
JSONObject json_user = json.getJSONObject("user");
// Clear all previous data in database
userFunction.logoutUser(getApplicationContext());
db.addUser(json_user.getString(KEY_NAME), json_user.getString(KEY_EMAIL), json.getString(KEY_UID), json_user.getString(KEY_CREATED_AT));
// Launch Dashboard Screen
Intent dashboard = new Intent(getApplicationContext(), DashboardActivity.class);
// Close all views before launching Dashboard
dashboard.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(dashboard);
// Close Registration Screen
finish();
}else{
// Error in registration
registerErrorMsg.setText("Error occured in registration");
}
}
} catch (JSONException e) {
e.printStackTrace();
}
}
});
// Link to Login Screen
btnLinkToLogin.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
Intent i = new Intent(getApplicationContext(),
LoginActivity.class);
startActivity(i);
// Close Registration View
finish();
}
});
}
}
The logcat looks like this:
03-24 01:20:22.154: E/AndroidRuntime(1787): FATAL EXCEPTION: main
03-24 01:20:22.154: E/AndroidRuntime(1787): android.os.NetworkOnMainThreadException
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1133)
03-24 01:20:22.154: E/AndroidRuntime(1787): at libcore.io.BlockGuardOs.connect(BlockGuardOs.java:84)
03-24 01:20:22.154: E/AndroidRuntime(1787): at libcore.io.IoBridge.connectErrno(IoBridge.java:127)
03-24 01:20:22.154: E/AndroidRuntime(1787): at libcore.io.IoBridge.connect(IoBridge.java:112)
03-24 01:20:22.154: E/AndroidRuntime(1787): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:192)
03-24 01:20:22.154: E/AndroidRuntime(1787): at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:459)
03-24 01:20:22.154: E/AndroidRuntime(1787): at java.net.Socket.connect(Socket.java:842)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.conn.scheme.PlainSocketFactory.connectSocket(PlainSocketFactory.java:119)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:144)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
03-24 01:20:22.154: E/AndroidRuntime(1787): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
03-24 01:20:22.154: E/AndroidRuntime(1787): at com.example.trial.library.JSONParser.getJSONFromUrl(JSONParser.java:47)
03-24 01:20:22.154: E/AndroidRuntime(1787): at com.example.trial.library.UserFunctions.loginUser(UserFunctions.java:43)
03-24 01:20:22.154: E/AndroidRuntime(1787): at com.example.trial.LoginActivity$1.onClick(LoginActivity.java:56)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.view.View.performClick(View.java:4240)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.view.View$PerformClick.run(View.java:17721)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.os.Handler.handleCallback(Handler.java:730)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.os.Handler.dispatchMessage(Handler.java:92)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.os.Looper.loop(Looper.java:137)
03-24 01:20:22.154: E/AndroidRuntime(1787): at android.app.ActivityThread.main(ActivityThread.java:5103)
03-24 01:20:22.154: E/AndroidRuntime(1787): at java.lang.reflect.Method.invokeNative(Native Method)
03-24 01:20:22.154: E/AndroidRuntime(1787): at java.lang.reflect.Method.invoke(Method.java:525)
03-24 01:20:22.154: E/AndroidRuntime(1787): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
03-24 01:20:22.154: E/AndroidRuntime(1787): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
03-24 01:20:22.154: E/AndroidRuntime(1787): at dalvik.system.NativeStart.main(Native Method)

Here you can't perform your network operation on the UI thread as of api level 11.
So for that you have to use AsyncTask or Thread.
Example of AsyncTask.
class DowloadTest extends AsyncTask<String, Integer, String>
{
#Override
protected void onPreExecute() {
pDialog = new ProgressDialog(YourActivityName.this);
pDialog.setMessage("Please wait..");
pDialog.setIndeterminate(true);
pDialog.setCancelable(false);
pDialog.show();
};
#Override
protected String doInBackground(String... params) {
// parse your data here
return null;
}
#Override
protected void onPostExecute(String result) {
// TODO Auto-generated method stub
super.onPostExecute(result);
pDialog.dismiss();
}
}
}
and after that execute this function whenever you need it like,
new DowloadTest().execute();
For more reference go Here

// you can add your json code in async task class
class callservice extends AsyncTask<String, String, String>
{
private ProgressDialog pDialog;
String message = "";
private String result;
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setCancelable(false);
pDialog.show();
}
/**
* getting All products from url
* */
protected String doInBackground(String... args)
{
// Write your json code which get data
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url)
{
// dismiss the dialog after getting all products
if (pDialog != null)
pDialog.dismiss();
}
}

Bcoz of your SDK tools are maybe Upgrade version doesnt support.. for example you create your project in SDK min level is 8 but your android SDk version tools is APK level 19 means it may occurs so go to your SDk Folder and delete tools Folder and then Copy your cuurent version of SDk tools must be put it in your SDK Folder.
you are using low level APK version means it will generate this line bcoz you want to access high high level code in Upgrade version supported methods means this lines will shows of your methods..
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
and also set this line in your activity
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB_MR2) {
int shortAnimTime = getResources().getInteger(
android.R.integer.config_shortAnimTime);
or
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
thank you.

I was also facing the same problem, solution which worked for me is :
If you don't wish to use AsyncTask in your activity, try adding below snippet in your onCreate of LoginActivity.java
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}
So this will save your time and effort for solving this error.
P.S. If you get error on these line after adding them to your activity, try cleaning your application. You can also try adding
#SuppressLint("NewApi")
before oncreate method. like this,
#SuppressLint("NewApi")
#Override
public void onCreate(Bundle savedInstanceState) {
Hope this well help you too.

how to stop jsonParser.makeHttpRequest in android

I crate app to check the database for login info by using jsonParser.makeHttpRequest
I try to make my app to stop after 10 second in case there is no internet connection or no response from the server. The code work however when the login button click for the second time the app crash
Could anyone please support why this happen
please see the below for the code
package com.example.pfms;
import java.util.ArrayList;
import java.util.List;
import org.apache.http.NameValuePair;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.BasicHttpParams;
import org.apache.http.params.HttpConnectionParams;
import org.apache.http.params.HttpParams;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.app.Activity;
import android.app.ListActivity;
import android.app.ProgressDialog;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;
import android.widget.Toast;
public class MainActivity extends Activity {
private String id,pass,p,logincheck;
private EditText username,password;
private Button login;
private CheckLogin cl;
private ProgressDialog pDialog;
private SharedPreferences prefs;
JSONParser jsonParser = new JSONParser();
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCT = "product";
private static final String url = "http://192.168.1.11/pfm/get_id.php";
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.login);
cl= new CheckLogin();
username=(EditText)findViewById(R.id.editText1);
password=(EditText)findViewById(R.id.editText2);
login=(Button)findViewById(R.id.button1);
prefs = this.getSharedPreferences("com.example.pfms", MODE_PRIVATE);
logincheck=prefs.getString("com.example.pfms.login", "0");
if(!logincheck.equals("0")){
Intent i=new Intent(MainActivity.this,TechOption.class);
Bundle info=new Bundle();
info.putString("techid",logincheck);
i.putExtras(info);
startActivity(i);
}
login.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
cl.execute();
}
});
}
class CheckLogin extends AsyncTask<String, String, String> {
/**
* Before starting background thread Show Progress Dialog
* */
#Override
protected void onPreExecute() {
super.onPreExecute();
pDialog = new ProgressDialog(MainActivity.this);
pDialog.setMessage("Checking Login info. Please wait...");
pDialog.setIndeterminate(false);
pDialog.setCancelable(true);
pDialog.show();
p="0";
pass="0";
Log.d("test", "dialog");
}
/**
* Getting product details in background thread
* */
protected String doInBackground(String... params) {
// updating UI from Background Thread
// runOnUiThread(new Runnable() {
// public void run() {
// Check for success tag
int success;
try {
Log.d("test", "run");
// Building Parameters
List<NameValuePair> params2 = new ArrayList<NameValuePair>();
id=username.getText().toString();
pass=password.getText().toString();
params2.add(new BasicNameValuePair("id",id));
// getting product details by making HTTP request
// Note that product details url will use GET request
// HttpParams httpParameters = new BasicHttpParams();
// HttpConnectionParams.setConnectionTimeout(httpParameters, 30000);
// HttpConnectionParams.setSoTimeout(httpParameters, 30000);
// DefaultHttpClient httpClient = new DefaultHttpClient(httpParameters);
messageHandler.sendEmptyMessageDelayed(0, 10000);
Log.d("test", "before");
JSONObject json = jsonParser.makeHttpRequest(
url, "GET", params2);
// check your log for json response
Log.d("Single Product Details", json.toString());
// json success tag
success = json.getInt(TAG_SUCCESS);
Log.d("test", "before success");
if (success == 1) {
// successfully received product details
JSONArray actiondetail = json
.getJSONArray(TAG_PRODUCT); // JSON Array
// get first product object from JSON Array
JSONObject c = actiondetail.getJSONObject(0);
// Storing each json item in variable
p="";
p = c.getString("pass");
Log.d("info", "p="+p);
Log.d("info", "pass="+pass);
}else{
Toast.makeText(getBaseContext(), "Wrong Username", Toast.LENGTH_LONG).show();
}
Log.d("test", "after success");
} catch (JSONException e) {
//pDialog.dismiss();
//Toast.makeText(getBaseContext(), "Please check internet connection", Toast.LENGTH_LONG).show();
e.printStackTrace();
}
// }
// });
return null;
}
/**
* After completing background task Dismiss the progress dialog
* **/
protected void onPostExecute(String file_url) {
// dismiss the dialog once got all details
pDialog.dismiss();
Log.d("test", "dismiss dailog");
if(p.contentEquals(pass)){
Intent i=new Intent(MainActivity.this,TechOption.class);
Bundle info=new Bundle();
info.putString("techid",id);
i.putExtras(info);
SharedPreferences.Editor editor = prefs.edit();
editor.putString("com.example.pfms.login",id);
editor.commit();
startActivity(i);
}
else{
Toast.makeText(getBaseContext(), "Wrong Password", Toast.LENGTH_LONG).show();
}
}
}
private Handler messageHandler = new Handler() {
public void handleMessage(Message msg) {
super.handleMessage(msg);
pDialog.dismiss();
Toast.makeText(getBaseContext(), "Please check internet connection", Toast.LENGTH_LONG).show();
cl.cancel(true);
}
};
}
please see the below for Error :
11-05 09:37:09.053: D/AndroidRuntime(1398): Shutting down VM
11-05 09:37:09.053: W/dalvikvm(1398): threadid=1: thread exiting with uncaught exception (group=0x41465700)
11-05 09:37:09.123: E/AndroidRuntime(1398): FATAL EXCEPTION: main
11-05 09:37:09.123: E/AndroidRuntime(1398): java.lang.IllegalStateException: Cannot execute task: the task is already running.
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:575)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.os.AsyncTask.execute(AsyncTask.java:534)
11-05 09:37:09.123: E/AndroidRuntime(1398): at com.example.pfms.MainActivity$2.onClick(MainActivity.java:79)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.view.View.performClick(View.java:4240)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.view.View$PerformClick.run(View.java:17721)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.os.Handler.handleCallback(Handler.java:730)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.os.Handler.dispatchMessage(Handler.java:92)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.os.Looper.loop(Looper.java:137)
11-05 09:37:09.123: E/AndroidRuntime(1398): at android.app.ActivityThread.main(ActivityThread.java:5103)
11-05 09:37:09.123: E/AndroidRuntime(1398): at java.lang.reflect.Method.invokeNative(Native Method)
11-05 09:37:09.123: E/AndroidRuntime(1398): at java.lang.reflect.Method.invoke(Method.java:525)
11-05 09:37:09.123: E/AndroidRuntime(1398): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
11-05 09:37:09.123: E/AndroidRuntime(1398): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
11-05 09:37:09.123: E/AndroidRuntime(1398): at dalvik.system.NativeStart.main(Native Method)

An object of an AsyncTask can be run only once. That is why you are getting the IllegalStateException.
Remove the object instantiation [cl= new CheckLogin()] from onCreate().
And instead,
login.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
new CheckLogin.execute(); // creating an anonymous object of the AsyncTask makes sure that you never use it again which prevents any IllegalStateExceptions
}
});