Question

I write the program, the program should give name,email and etc of textboxes and send to a url but the program has stopped and NullPointerException error in run time.

I write the code of my porgram. Please read and help me. Thanks

SignUpAsync.java:

public class SignUpAsync extends AsyncTask<List<NameValuePair>,Void,String>{
@Override
protected String doInBackground(List<NameValuePair>... nameValuePairs) {

    HttpPost httpPost=new HttpPost("http://myURL.com");
    HttpClient httpClient=new DefaultHttpClient();
    HttpResponse httpRespons = null;

    try {
        httpPost.setEntity(new UrlEncodedFormEntity(nameValuePairs[0]));
        httpRespons=httpClient.execute(httpPost);
    } catch (UnsupportedEncodingException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ClientProtocolException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    HttpEntity entity=httpRespons.getEntity();
    InputStream is = null;
    try {
        is=entity.getContent();
    } catch (IllegalStateException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

    return convertStreamToString(is);

}

private String convertStreamToString(InputStream is){
    BufferedReader bfReader=new BufferedReader(new InputStreamReader(is));
    StringBuilder sb=new StringBuilder();
    String line="";
    try {
        while((line=bfReader.readLine())!=null)
            //
            sb.append(line);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    try {
        is.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return sb.toString();

}   
}

SignUp.java:

public class SignUp extends Activity{

private Button signUp;
private EditText userName;
private EditText userEmail;
private EditText userPass;
private EditText userPasscode;
private EditText userPhone;

@Override
public void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.rewards_signup);

    initView();

    String[] params = null;
    params[0]=userName.getText().toString();
    params[1]=userEmail.getText().toString();
    params[2]=userPass.getText().toString();
    params[3]=userPasscode.getText().toString();
    params[4]=userPhone.getText().toString();

    List<NameValuePair> nameValuePairs=new ArrayList<NameValuePair>(5);
    nameValuePairs.add(new BasicNameValuePair("User Name",params[0]));
    nameValuePairs.add(new BasicNameValuePair("User Email Id",params[1]));
    nameValuePairs.add(new BasicNameValuePair("User Password",params[2]));
    nameValuePairs.add(new BasicNameValuePair("User Passcode",params[3]));
    nameValuePairs.add(new BasicNameValuePair("User Phone Number",params[4]));

    AsyncTask<List<NameValuePair>, Void, String> async;
    async=new SignUpAsync().execute(nameValuePairs);
    try {
        String result=async.get();
        if(result!=null)
            Log.i("result", result);
        else
            Log.i("result", "null");
    } catch (InterruptedException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } catch (ExecutionException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}
private void initView(){
    signUp=(Button)findViewById(R.id.signup_id);
    userName=(EditText)findViewById(R.id.name_id);
    userEmail=(EditText)findViewById(R.id.email_id);
    userPass=(EditText)findViewById(R.id.password_id);
    userPasscode=(EditText)findViewById(R.id.pincode_id);
    userPhone=(EditText)findViewById(R.id.phonnum_id);
}
}

LogCat:

12-05 08:46:00.063: W/dalvikvm(15436): threadid=1: thread exiting with uncaught exception (group=0x40a7e1f8)
12-05 08:46:00.071: E/AndroidRuntime(15436): FATAL EXCEPTION: main
12-05 08:46:00.071: E/AndroidRuntime(15436): java.lang.RuntimeException: Unable to start activity ComponentInfo{org.example.loyaltier/org.example.rewards.SignUp}: java.lang.NullPointerException
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread.access$600(ActivityThread.java:122)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.os.Handler.dispatchMessage(Handler.java:99)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.os.Looper.loop(Looper.java:137)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread.main(ActivityThread.java:4340)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at java.lang.reflect.Method.invokeNative(Native Method)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at java.lang.reflect.Method.invoke(Method.java:511)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at dalvik.system.NativeStart.main(Native Method)
12-05 08:46:00.071: E/AndroidRuntime(15436): Caused by: java.lang.NullPointerException
12-05 08:46:00.071: E/AndroidRuntime(15436):    at org.example.rewards.SignUp.onCreate(SignUp.java:35)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.Activity.performCreate(Activity.java:4465)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
12-05 08:46:00.071: E/AndroidRuntime(15436):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)
12-05 08:46:00.071: E/AndroidRuntime(15436):    ... 11 more
12-05 08:46:01.579: I/Process(15436): Sending signal. PID: 15436 SIG: 9

Cheers.

Answer 1

You need to initialize params:

String[] params = new String[5];

---

Also understand that AsyncTask#get() this line:

String result=async.get();

As described in the documentation, “Waits if necessary for the computation to complete, and then retrieves its result.” will block the main thread until the AsyncTask has completed. This defies the purpose of the AsyncTask…