How to solve java.lang.RuntimeException: Unable to start activity?

Question

i'm making an app that has a sign in or log in button, the log in button works perfectly but the sign up button gives me a fatal error, making the AVD to stop running the app, this is the code of the sign up activity

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

    // Set up the signup form.
    usernameView = (EditText) findViewById(R.id.username);
    passwordView = (EditText) findViewById(R.id.password);
    passwordAgainView = (EditText) findViewById(R.id.passwordAgain);

    // Set up the submit button click handler
    findViewById(R.id.action_button).setOnClickListener(new View.OnClickListener() {
        public void onClick(View view) {

            // Validate the sign up data
            boolean validationError = false;
            StringBuilder validationErrorMessage =
                    new StringBuilder(getResources().getString(R.string.error_intro));
            if (isEmpty(usernameView)) {
                validationError = true;
                validationErrorMessage.append(getResources().getString(R.string.error_blank_username));
            }
            if (isEmpty(passwordView)) {
                if (validationError) {
                    validationErrorMessage.append(getResources().getString(R.string.error_join));
                }
                validationError = true;
                validationErrorMessage.append(getResources().getString(R.string.error_blank_password));
            }
            if (!isMatching(passwordView, passwordAgainView)) {
                if (validationError) {
                    validationErrorMessage.append(getResources().getString(R.string.error_join));
                }
                validationError = true;
                validationErrorMessage.append(getResources().getString(
                        R.string.error_mismatched_passwords));
            }
            validationErrorMessage.append(getResources().getString(R.string.error_end));

            // If there is a validation error, display the error
            if (validationError) {
                Toast.makeText(SignUpActivity.this, validationErrorMessage.toString(), Toast.LENGTH_LONG)
                        .show();
                return;
            }

            // Set up a progress dialog
            final ProgressDialog dlg = new ProgressDialog(SignUpActivity.this);
            dlg.setTitle("Please wait.");
            dlg.setMessage("Signing up.  Please wait.");
            dlg.show();

            // Set up a new Parse user
            ParseUser user = new ParseUser();
            user.setUsername(usernameView.getText().toString());
            user.setPassword(passwordView.getText().toString());
            // Call the Parse signup method
            user.signUpInBackground(new SignUpCallback() {

                @Override
                public void done(ParseException e) {
                    dlg.dismiss();
                    if (e != null) {
                        // Show the error message
                        Toast.makeText(SignUpActivity.this, e.getMessage(), Toast.LENGTH_LONG).show();
                    } else {
                        // Start an intent for the dispatch activity
                        Intent intent = new Intent(SignUpActivity.this, DispatchActivity.class);
                        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK | Intent.FLAG_ACTIVITY_NEW_TASK);
                        startActivity(intent);
                    }
                }
            });
        }
    });
}

private boolean isEmpty(EditText etText) {
    if (etText.getText().toString().trim().length() > 0) {
        return false;
    } else {
        return true;
    }
}

private boolean isMatching(EditText etText1, EditText etText2) {
    if (etText1.getText().toString().equals(etText2.getText().toString())) {
        return true;
    } else {
        return false;
    }
}

and here is the manifest

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

<application

    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme"
    android:name=".ParseStarter">
    <activity
        android:screenOrientation="portrait"
        android:name=".MainActivity"
        android:label="@string/app_name" >

    </activity>

    <activity android:name=".SignUpOrLogInActivity"

        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=".DispatchActivity"/>
    <activity android:name=".LoginActivity" />
    <activity android:name=".SignUpActivity" />


    <meta-data android:name="com.facebook.sdk.ApplicationId" android:value="@string/facebook_app_id"/>


</application>

here is the logCat

Process: com.sebasdeldihotmail.mediocre11, PID: 2020
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sebasdeldihotmail.mediocre11/com.sebasdeldihotmail.mediocre11.SignUpActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2298)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)
        at android.app.ActivityThread.access$800(ActivityThread.java:144)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:135)
        at android.app.ActivityThread.main(ActivityThread.java:5221)
        at java.lang.reflect.Method.invoke(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:372)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.sebasdeldihotmail.mediocre11.SignUpActivity.onCreate(SignUpActivity.java:35)
        at android.app.Activity.performCreate(Activity.java:5933)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1105)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2251)

at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2360)

at android.app.ActivityThread.access$800(ActivityThread.java:144)

at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1278)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:135)
            at android.app.ActivityThread.main(ActivityThread.java:5221)
            at java.lang.reflect.Method.invoke(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:372)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

here is the code of the class that has the button that calls the sign up activity

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

    // Log in button click handler
    ((Button) findViewById(R.id.login)).setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Starts an intent of the log in activity
            startActivity(new Intent(SignUpOrLogInActivity.this, LoginActivity.class));
        }
    });

    // Sign up button click handler
    ((Button) findViewById(R.id.signup)).setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) {
            // Starts an intent for the sign up activity
            startActivity(new Intent(SignUpOrLogInActivity.this, SignUpActivity.class));
        }
    });
}

}

and here is the layout of the sign up

   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#67AAE4">


    <EditText
        android:id="@+id/username"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/prompt_username"
        android:inputType="textEmailAddress"
        android:maxLines="1"
        android:singleLine="true" />

    <EditText
        android:id="@+id/password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/prompt_password"
        android:inputType="textPassword"
        android:maxLines="1"
        android:singleLine="true" />

    <EditText
        android:id="@+id/passwordAgain"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="@string/prompt_password_again"
        android:imeActionLabel="@string/action_sign_in_short"
        android:imeOptions="actionUnspecified"
        android:inputType="textPassword"
        android:maxLines="1"
        android:singleLine="true" />



</LinearLayout>

and here is the layout where the sign up button appears

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#67AAE4">

<Button
    android:id="@+id/signup"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Sign Up"/>

<Button
    android:id="@+id/login"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Login"/>


<com.facebook.widget.LoginButton
    android:id="@+id/authButton"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center_horizontal"
    android:layout_marginTop="30dp"
    />

Thank you very much for reading :) .

Add stack trace. Otherwise it will take some time to search for a bug in your code. — srumjant, Dec 18 '14 at 14:12
ok but im kinda new here and im not sure how to correctly put the logcat on the post, should i paste it and thats all? — Sebastian Delgado Diaz, Dec 18 '14 at 14:15
Insert it inside of code block. Same as you did with manifest and activity class. — srumjant, Dec 18 '14 at 14:16
`android:screenOrientation="portrait"` makes me sad.. but it's offtopic I know... — J.G.Sebring, Dec 18 '14 at 14:20
Try making following change ((Button)findViewById(R.id.action_button)).setOnClickListener(.....rest of your code....); Also make sure action_button is defined in the layout. — Tabrej Khan, Dec 18 '14 at 14:22
yes, i´m using fragments, the activity that goes after the log in has 4 fragments — Sebastian Delgado Diaz, Dec 18 '14 at 14:25
possible duplicate of [What is a Null Pointer Exception, and how do I fix it?](http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do-i-fix-it) — njzk2, Dec 18 '14 at 15:40

score 5 · Answer 1 · answered Dec 18 '14 at 14:19

5

java.lang.NullPointerException: Attempt to invoke virtual method 'void android.view.View.setOnClickListener(android.view.View$OnClickListener)' on a null object reference

It appears your signup_activity.xml layout does not have a view with id action_button, and findViewById() returns null.

answered Dec 18 '14 at 14:19

laalto

150,114
66
286
303

its rare, because it actually does have the button, let me put the xml code on the question – Sebastian Delgado Diaz Dec 18 '14 at 14:30
So where's the layout that contains `action_button`? – laalto Dec 18 '14 at 14:39
post xml of R.layout.signup_activity - that is where it looks for `action_button` – J.G.Sebring Dec 18 '14 at 14:40
you are right, what a dump mistake, thank you very much. – Sebastian Delgado Diaz Dec 18 '14 at 15:05

score 1 · Accepted Answer · answered Dec 18 '14 at 14:32

1

The view you are adding the onClickListener to, r.id.action_button, is not found, hence the NullPointerException.

So make sure you have it in the current view, signup_activity.xml.

More:

To make your 'onCreate'-method less chunky, and to avoid this to happen again, consider using android:onClick on your button in the layoutfile, signup_activity.xml.

<Button
android:id="@+id/action_button"
android:onClick="onSignUpClick"
...
/>

Then in SignUpActivity.java add the method:

public void onSignUpClick(View view) {
   // add code here instead of creating onClickListener in onCreate...
}

answered Dec 18 '14 at 14:32

J.G.Sebring

5,934
1
31
42

It looks like he already use onClick property, but for some reason click listener set to null instead of appropriate component (activity, fragment whatever) – Fyodor Volchyok Dec 18 '14 at 14:36
There is currently no sign of onClick property in xml. You are pragmatically adding a onClickListener on the view. It's hard to say though without the xml. Can you add xml of signup_activity? – J.G.Sebring Dec 18 '14 at 14:43
and can you find a view with id `action_button` in it? ;) – J.G.Sebring Dec 18 '14 at 14:52
both on them are there now. – Sebastian Delgado Diaz Dec 18 '14 at 14:55
both our answers hold the solution - you have no view (button or whatever) with id `action_button` in your layout. You program crashes in onCreate() where you have 'findViewById(R.id.action_button)` - because there is none - ie. NullPointerException – J.G.Sebring Dec 18 '14 at 14:58
you are right, what a dump mistake, thank you very much. – Sebastian Delgado Diaz Dec 18 '14 at 15:05

How to solve java.lang.RuntimeException: Unable to start activity?

2 Answers2