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Android

Steven Buchko
Steven Buchko
4,387 Points
Posted by Steven Buchko
Steven Buchko
4,387 Points

Null Pointer Exception on Log In

java.lang.NullPointerException: Attempt to invoke virtual method 'com.parse.ParseHttpClient com.parse.ParsePlugins.restClient()' on a null object reference

I receive this error if I attempt to Log In without first visiting the Sign Up Activity. I tried enabling the local data store and initializing Parse in the Log In Activity (currently I do it in the Sign Up activity), but that seemed to cause other issues.

LogInActivity

package com.stevenbuchko.here;

import android.app.AlertDialog; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.TextView;

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

public class LogInActivity extends AppCompatActivity {

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_log_in);




    mUsername = (EditText) findViewById(R.id.usernameField);
    mPassword = (EditText) findViewById(R.id.passwordField);
    mLoginButton = (Button) findViewById(R.id.logInBtn);
    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);
        }
    });

    mLoginButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            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)
                        .setPositiveButton(android.R.string.ok, null)
                        .setTitle(R.string.login_error_title);

                AlertDialog dialog = builder.create();
                dialog.show();
            }
            else {
                // Login
                setProgressBarIndeterminate(true);
                ParseUser.logInInBackground(username, password, new LogInCallback() {
                    @Override
                    public void done(ParseUser parseUser, ParseException e) {
                        setProgressBarIndeterminate(false);

                        if (e == null) {
                            // Success!

                            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())
                                    .setTitle(R.string.login_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.menu_log_in, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

}

SignUpActivity

package com.stevenbuchko.here;

import android.app.AlertDialog; import android.content.Intent; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.view.Menu; import android.view.MenuItem; import android.view.View; import android.widget.Button; import android.widget.EditText;

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

public class SignUpActivity extends AppCompatActivity {

protected EditText mUsername;
protected EditText mPassword;
protected EditText mEmail;
protected Button mSignUpButton;

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

    Parse.enableLocalDatastore(this);
    Parse.initialize(this);

    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()) {
                AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
                builder.setMessage(R.string.sign_up_username_error_message)
                        .setTitle(R.string.sign_up_error_title)
                        .setPositiveButton(android.R.string.ok , null);
                AlertDialog dialog = builder.create();
                dialog.show();
            } else if (password.isEmpty()) {
                AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
                builder.setMessage(R.string.sign_up_password_error_message)
                        .setTitle(R.string.sign_up_error_title)
                        .setPositiveButton(android.R.string.ok , null);
                AlertDialog dialog = builder.create();
                dialog.show();
            } else if (email.isEmpty()) {
                AlertDialog.Builder builder = new AlertDialog.Builder(SignUpActivity.this);
                builder.setMessage(R.string.sign_up_email_error_message)
                        .setTitle(R.string.sign_up_error_title)
                        .setPositiveButton(android.R.string.ok, null);
                AlertDialog dialog = builder.create();
                dialog.show();
            } else {
                // create the user
                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.sign_up_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.menu_sign_up, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}

}