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Posted July 18, 2014 3:31am by

Fatal Error when trying to open LoginActivity intent

At this point, whenever my app trys to use the navigateToLogin() method, it crashes. In the logcat it gives me java.lang.Runtimeexception: Unable to start activity Component info {...LoginActivity}: java.lang.NullPointerException

Any part of my code that calls upon this method and tries to load the LoginActivity intent instantly crashes the app.

Any thoughts? --What other info is pertinent to answering this question?

One other thing, when I debug and step into the navigateToLogin() method, the first line works to create a new intent, but when I step into the next line it says this:

Class File Editor

Source not found The JAR file ...android.jar has no source attachment.

Not sure what that means or why it is happening.

6 Answers

July 18, 2014 9:10am

Could you copy the contents of LogCat in here - the nullPointer is a good start but, somewhere, it'll tell you the line of code that's causing it. That's a good starting point!

Don't worry about the JAR file - it does that! ;-)

July 18, 2014 1:38pm

LogCat:

07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): 07-17 21:45:03.076: E/AndroidRuntime(22107): FATAL EXCEPTION: main Process: com.example.ribbit, PID: 22107 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.ribbit/com.example.ribbit.LoginActivity}: java.lang.NullPointerException at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184) 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.ribbit.LoginActivity.onCreate(LoginActivity.java:47) at android.app.Activity.performCreate(Activity.java:5231) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148) ... 11 more

Thanks for the reply, Steve.

July 19, 2014 4:11am

Okay, thank you for your help Steve, I found the problem. My onClickListener was references the wrong id (SignUpButton instead of LoginButton). Stupid mistake, but you helped me narrow it down, and gave me the idea of where to start looking.

July 18, 2014 2:40pm

That's a bit opaque ... can you post your code for LoginActivity too? Maybe that'll throw something up!

Cheers,

Steve.

July 19, 2014 12:26am

package com.example.ribbit;

import com.parse.LogInCallback; import com.parse.ParseException; import com.parse.ParseUser; import com.parse.SignUpCallback;

import android.os.Bundle; import android.app.Activity; import android.app.AlertDialog; import android.content.Intent; import android.view.Menu; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView;

public class LoginActivity extends Activity {

protected EditText mUsername;
protected EditText mPassword;

protected Button mLoginButton;
protected TextView mSignUpTextView;


@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_login);

    mSignUpTextView = (TextView)findViewById(R.id.signUpText);
    mSignUpTextView.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            Intent intent = new Intent(LoginActivity.this, SignUpActivity.class);
            startActivity(intent);
        }
    });

    mUsername = (EditText)findViewById(R.id.usernameField);
    mPassword = (EditText)findViewById(R.id.passwordText);

    mLoginButton = (Button)findViewById(R.id.signUpButton);

    mLoginButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            String username = mUsername.getText().toString();
            String password = mPassword.getText().toString();


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


            if (username.isEmpty() || password.isEmpty()){
                AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this);
                builder.setMessage(R.string.login_error_message);
                builder.setTitle(R.string.signUp_error_title);
                builder.setPositiveButton(android.R.string.ok, null);
                AlertDialog dialog = builder.create();
                dialog.show();
            }
            else{
                ParseUser.logInInBackground(username, password, new LogInCallback() {

                    @Override
                    public void done(ParseUser user, ParseException e) {
                        // TODO Auto-generated method stub
                        if (e==null){
                            Intent intent = new Intent(LoginActivity.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(LoginActivity.this);
                            builder.setMessage(e.getMessage());
                            builder.setTitle(R.string.signUp_error_title);
                            builder.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.activity_login, menu);
    return true;
}

}

Here is the code for LoginActivity. It could be something here in the onCreate() method, since it crashes as soon as LoginActivity tries to start.

One other thing, I have found that if I change the navigatetoLogin() function to load the signUpActivity, everything works fine, so I figure the problem must be in this LoginActivity somewhere, right?

*UPDATE: I have isolated it to this piece of code:

    mLoginButton.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub



            String username = mUsername.getText().toString();
            String password = mPassword.getText().toString();


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


            if (username.isEmpty() || password.isEmpty()){
                AlertDialog.Builder builder = new AlertDialog.Builder(LoginActivity.this);
                builder.setMessage(R.string.login_error_message);
                builder.setTitle(R.string.signUp_error_title);
                builder.setPositiveButton(android.R.string.ok, null);
                AlertDialog dialog = builder.create();
                dialog.show();
            }
            else{
                ParseUser.logInInBackground(username, password, new LogInCallback() {

                    @Override
                    public void done(ParseUser user, ParseException e) {
                        // TODO Auto-generated method stub
                        if (e==null){
                            Intent intent = new Intent(LoginActivity.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(LoginActivity.this);
                            builder.setMessage(e.getMessage());
                            builder.setTitle(R.string.signUp_error_title);
                            builder.setPositiveButton(android.R.string.ok, null);
                            AlertDialog dialog = builder.create();
                            dialog.show();
                        }
                    }
                });
            }
        }


    });

Thanks in advance for your help, Steve.

July 19, 2014 7:52am

Glad you got it sorted!

April 3, 2015 8:11pm

So I believe I am having the same problem as you did, what exactly did you do to resolve this?

May 7, 2015 10:30am

Wow, and I told myself not to forget to change it after copying and pasting the code from SignUpActivity...doesn't take much to distract me lol.

In case anyone is still having issues, the offending line of code was in the onCreate() method in LoginActivity:

mLoginButton = (Button)findViewById(R.id.signUpButton);

Should be:

mLoginButton = (Button)findViewById(R.id.loginButton);

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Adam Zollinger

Adam Zollinger

Fatal Error when trying to open LoginActivity intent

6 Answers

Steve Hunter

Steve Hunter

Adam Zollinger

Adam Zollinger

Adam Zollinger

Adam Zollinger

Steve Hunter

Steve Hunter

Adam Zollinger

Adam Zollinger

Steve Hunter

Steve Hunter

Zachary Zell

Zachary Zell

Greg Austin

Greg Austin