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so I'm trying to use a Switch toggle widget in Android Studio and it is giving a null object reference, this is the code that i am using. 

`import android.content.DialogInterface;
import android.content.Intent;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.CompoundButton;
import android.widget.Switch;
import android.widget.TextView;

public class ProfileActivity extends AppCompatActivity implements CompoundButton.OnCheckedChangeListener {


    TextView username;
    Switch sw1;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        sw1 = (Switch)findViewById(R.id.switch1);
        final String usersUsername = getIntent().getExtras().getString("username");
        Log.d("USERNAME",usersUsername);
        setContentView(R.layout.activity_profile);
        username=(TextView)findViewById(R.id.userNameTxt);
        username.append(usersUsername);
        sw1.setOnCheckedChangeListener(this);

    }
    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        if (sw1.isChecked()){
            AlertDialog.Builder dialog = new AlertDialog.Builder(ProfileActivity.this);
            dialog.setCancelable(false);
            dialog.setTitle("Turn on notifications");
            dialog.setMessage("Are you sure you want to turn notifications on?" );
            dialog.setPositiveButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int id) {
                    //Action for "OK".
                    sw1.setChecked(true);
                }
            });
            dialog.setNegativeButton("cancel", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialogInterface, int i) {
                    sw1.setChecked(false);
                }
            });
        }

        else {
            sw1.setChecked(false);
        }
    }



}

when I try to run this I get this error: Attempt to invoke virtual method 'void android.widget.Switch.setOnCheckedChangeListener(android.widget.CompoundButton$OnCheckedChangeListener)' on a null object reference

I don't see how I can set anything to the object to not make it null, what am i doing wrong?

Charlie Ansell
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  • Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) – Joe C Feb 03 '18 at 00:12
  • 1
    Call `setContentView()` before `findViewById`. [Link](https://stackoverflow.com/questions/3264610/findviewbyid-returns-null) – dewey Feb 03 '18 at 00:38
  • wow I am an idiot, thanks, that's what the problem was, this is what I get coding late at night :p – Charlie Ansell Feb 03 '18 at 00:44

0 Answers0