App crahing when Button declared outside onCreate method

Question

The following code crashes the app

public class SharedPreferencesActivity extends AppCompatActivity {

Button b1=(Button)findViewById(R.id.buttonSave); //**ERROR**

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

Whereas the following code works fine

 public class SharedPreferencesActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_shared_preferences);
    Button b1=(Button)findViewById(R.id.buttonSave);//**REPLACED BUTTON DECLARATION**
}

Why is this happening?

`Why is this happening?` because you can't declare stuff like that outside on create — a_local_nobody, May 14 '21 at 07:51
View has not been initalised. Please google your question before asking — lyncx, May 14 '21 at 07:51
What i wanted to do is use Button outside of onCreate() method. Found out that First I need to declare button outside method and initialize using oncreate(). — Gaurav Thapa, May 14 '21 at 08:03

Explisam · Accepted Answer · 2021-05-14T08:20:47.463

0

If you want a reference to your button globally then you should declare it outside then initialize it in onCreate

Button b1; //declare the button variable

public class SharedPreferencesActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_shared_preferences);

    b1 = (Button) findViewById(R.id.buttonSave); //initialize on creation
}

You should read more into the basics of Java when learning Android

edited May 14 '21 at 08:20

answered May 14 '21 at 07:59

Explisam

749
13
26

Button button; //declare the button variable public class SharedPreferencesActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_shared_preferences); button = (Button) findViewById(R.id.buttonSave); //initialize on creation } – Александр Волошиновский May 14 '21 at 08:15

App crahing when Button declared outside onCreate method

1 Answers1