回调内的意图-android

Question

Im using Parse for my back end and just created a simple login app where I am trying to add an intent to go to the home screen from my login screen.Here's my code:

public void loginClicked(View v)
{
    // Retrieve the text entered from the EditText
    usernametxt = username.getText().toString();
    passwordtxt = password.getText().toString();

    // Send data to Parse.com for verification
    ParseUser.logInInBackground(usernametxt,
            passwordtxt,
            new LogInCallback(){

                @Override
                public void done(ParseUser user, ParseException e) {
                    // TODO Auto-generated method stub
                    if (user != null) {
                        // If user exist and authenticated, send user to Welcome.class
                     Intent intent2 = new Intent(MainActivity.this,Home.class);
                 startActivity(intent2);
                        Toast.makeText(getApplicationContext(),
                                "Successfully Logged in",
                                Toast.LENGTH_LONG).show();
                        finish();
                    } else {
                        Toast.makeText(
                                getApplicationContext(),
                                "No such user exist, please signup",
                                Toast.LENGTH_LONG).show();
                    }
                }});
}
}

So according to the code my app should go to the "Home" page but it crashes and stops.Any way around this?

Answer 1

loginInBackground suggests that you are performing operations in a thread different from the UI Thread. But only the UI Thread can show a toast (or modify UI elements).

 Toast.makeText(getApplicationContext(),
                                "Successfully Logged in",
                                Toast.LENGTH_LONG).show();

You can use an Handler or runOnUiThread to overcame your issue

Answer 2

AS @Blackbelt has suggested you need to run Toast in another thread. Use the Following Code

    Handler mHandler = new Handler();//Best Initiated inside the onCreate method of your  activity

And this code where you wanna toast

mHandler.post(new Runnable() {
                    public void run() {
                        Toast.makeText(getApplicationContext(),
                                "Successfully Logged in",
                                Toast.LENGTH_LONG).show();
                    }
                });

Alternatively you can use *runonUiThread* :

                runOnUiThread(new Runnable() {

                    Toast.makeText(getApplicationContext(),
                                "Successfully Logged in",
                                Toast.LENGTH_LONG).show();
                });