Button click causing null pointer

Question

Every time I click on the button, the app crashes. I have trouble finding the bug, but I'm sure it has to do something with either the onClickListener, or the onClick function.

Note: I'm using Parse API for some back end stuff. But I highly doubt it has anything to do with any of the Parse stuff.

Here's what my code looks like:

public class SignUpActivity extends Activity {

    protected EditText mUserName;
    protected EditText mPassword;
    protected EditText mEmail;
    protected Button mSignUpButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
        setContentView(R.layout.activity_sign_up);

        mUserName = (EditText) findViewById(R.id.usernameField);
        mPassword = (EditText) findViewById(R.id.passwordField);
        mEmail = (EditText) findViewById(R.id.emailField);
        mSignUpButton = (Button) findViewById(R.id.signupButton);

        mSignUpButton.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                String username = mUserName.getText().toString();
                String password = mPassword.getText().toString();
                String email = mEmail.getText().toString();

                username = username.trim();
                password = password.trim();
                email = email.trim();

                if(username.isEmpty() || password.isEmpty() || email.isEmpty()){
                    AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
                    builder.setMessage(R.string.signup_error_message)
                           .setTitle(R.string.signup_error_title)
                           .setPositiveButton(android.R.string.ok, null);
                    AlertDialog dialog = builder.create();
                    dialog.show();
                }
                else{

                    setProgressBarIndeterminateVisibility(true);
                    ParseUser newUser = new ParseUser();
                    newUser.setUsername(username);
                    newUser.setPassword(password);
                    newUser.setEmail(email);
                    newUser.signUpInBackground(new SignUpCallback() {

                        @Override
                        public void done(ParseException e) {
                            setProgressBarIndeterminateVisibility(false);
                            if(e == null){
                                // success
                                Intent intent = new Intent(SignUpActivity.this, MainActivity.class);
                                intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
                                intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);
                                startActivity(intent);
                            }
                            else{
                                AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
                                builder.setMessage(e.getMessage())
                                       .setTitle(R.string.signup_error_title)
                                       .setPositiveButton(android.R.string.ok, null);
                                AlertDialog dialog = builder.create();
                                dialog.show();
                            }
                        }
                    });
                }
            }
        });
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.sign_up, menu);
        return true;
    }

}

Here's my Log Cat:

04-14 14:19:05.881: E/AndroidRuntime(1156): FATAL EXCEPTION: main 04-14 14:19:05.881:
E/AndroidRuntime(1156): Process: com.ebad.ribbit, PID: 1156 04-14 14:19:05.881: 
E/AndroidRuntime(1156): java.lang.NullPointerException 04-14 14:19:05.881:
E/AndroidRuntime(1156): at com.ebad.ribbit.SignUpActivity$1.onClick(SignUpActivity.java:40) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at android.view.View.performClick(View.java:4438) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at android.view.View$PerformClick.run(View.java:18422) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.os.Handler.handleCallback(Handler.java:733) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at android.os.Handler.dispatchMessage(Handler.java:95) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at android.os.Looper.loop(Looper.java:136) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at android.app.ActivityThread.main(ActivityThread.java:5017) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at java.lang.reflect.Method.invokeNative(Native Method) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at java.lang.reflect.Method.invoke(Method.java:515) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779) 04-14 14:19:05.881: 
E/AndroidRuntime(1156): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595) 04-14 14:19:05.881:
E/AndroidRuntime(1156): at dalvik.system.NativeStart.main(Native Method)

EDIT:

As requested, here is line 40:

String username = mUserName.getText().toString();

EDIT 2:

Here is the log cat after adding Log.i(TAG, mUserName == null ? "mUserName is null" : mUserName.getText() == null ? "mUserName.getText() is null" : "nothing is null"); :

04-14 15:21:47.955: E/AndroidRuntime(1318): FATAL EXCEPTION: main
04-14 15:21:47.955: E/AndroidRuntime(1318): Process: com.ebad.ribbit, PID: 1318
04-14 15:21:47.955: E/AndroidRuntime(1318): java.lang.NullPointerException
04-14 15:21:47.955: E/AndroidRuntime(1318):     at com.ebad.ribbit.SignUpActivity$1.onClick(SignUpActivity.java:43)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.view.View.performClick(View.java:4438)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.view.View$PerformClick.run(View.java:18422)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.os.Handler.handleCallback(Handler.java:733)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.os.Handler.dispatchMessage(Handler.java:95)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.os.Looper.loop(Looper.java:136)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at android.app.ActivityThread.main(ActivityThread.java:5017)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at java.lang.reflect.Method.invokeNative(Native Method)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at java.lang.reflect.Method.invoke(Method.java:515)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
04-14 15:21:47.955: E/AndroidRuntime(1318):     at dalvik.system.NativeStart.main(Native Method)

EDIT 3:

Upon Request, here is my activity_sign_up.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".SignUpActivity" >

    <EditText
        android:id="@+id/userNameField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true"
        android:hint="@string/username_hint"
        android:ems="10" >

        <requestFocus />
    </EditText>

    <EditText
        android:id="@+id/passwordField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/userNameField"
        android:ems="10"
        android:hint="@string/password_hint"
        android:inputType="textPassword" />

    <EditText
        android:id="@+id/emailField"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_below="@+id/passwordField"
        android:ems="10"
        android:hint="@string/email_hint"
        android:inputType="textEmailAddress" />

    <Button
        android:id="@+id/signupButton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/emailField"
        android:layout_below="@+id/emailField"
        android:layout_marginTop="50dp"
        android:text="@string/sign_up_button_label" />

</RelativeLayout>

Answer 1

If mUsername is null , calling getText() on it will cause a NullPointerException . You should check that it's not null before doing this. Try changing to the following:

        if(mUserName == null || mPassword == null || mEmail == null){
            AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
            builder.setMessage(R.string.signup_error_message)
                   .setTitle(R.string.signup_error_title)
                   .setPositiveButton(android.R.string.ok, null);
            AlertDialog dialog = builder.create();
            dialog.show();
        }

        String username = mUserName.getText().toString();
        String password = mPassword.getText().toString();
        String email = mEmail.getText().toString();

        username = username.trim();
        password = password.trim();
        email = email.trim();

Answer 2

Do this please:

@Override
public void onClick(View v) {
     if(mUserName != null && mPassword != null && mEmail != null && mUserName.getText() != null && mPassword.getText() != null && mEmail.getText() != null)
     {
          Your original code here.
     }
}

Update: Typo

 mUserName = (EditText) findViewById(R.id.usernameField); should be userNameField?  
 <EditText android:id="@+id/userNameField" ...

Answer 3

Try

AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());

https://developer.android.com/guide/topics/ui/dialogs.html

Also make sure that SignUpActivity is declared in the app manifest. I guess make sure that all activities are set up in the manifest.

EDIT 1 If line 40 is the issue, then mUserName is null or mUserName.getText() is null. So create a couple checks before hand and also add some debug logs to just verify that they are not null.

Make sure that R.layout.activity_sign_up has usernameField as an id. Also make sure in any other app/res/layout folders (ie layout-v14), that all R.layout.activity_sign_up has the edittext as well.

Answer 4

If this errors occurred in your line 40, that means your are getting null from your EditText.

Try it in every place you are getting a string. At least it will save you from getting null pointer exception from EditText.

String username = String.valueOf(mUserName.getText());
String password = String.valueOf(mPassword.getText());
String email = String.valueOf(mEmail.getText());