问题
The question is quite simple. But I want to know where exactly do we make our references to the gui elements? As in which is the best place to define:
final EditText edit = (EditText) findViewById(R.id.text_xyz);
edit.getText.tostring();
When I try it doing inside the default oncreate() I get null values. So for best practice, do u recommend a separate class for referring these already defined gui elements in main.xml. From here we can call various methods of these elements like gettext or settext?
回答1:
Well, it depends on your needs. Very often I keep my references to widgets in activity (as a class fields) - and set them in onCreate method. I think that is a good idea
Probably the reason for your nulls is that you are trying to call findViewById() before you set contentView() in your onCreate() method - please check that.
回答2:
The quickest solution to your problem I believe is that you simply are missing parentheses on your getText. Simply add () to edit.getText().toString() and that should solve it
回答3:
If you are doing it before the setContentView() method call, then the values will be null.
This will result in null:
super.onCreate(savedInstanceState);
Button btn = (Button)findViewById(R.id.btnAddContacts);
String text = (String) btn.getText();
setContentView(R.layout.main_contacts);
while this will work fine:
super.onCreate(savedInstanceState);
setContentView(R.layout.main_contacts);
Button btn = (Button)findViewById(R.id.btnAddContacts);
String text = (String) btn.getText();
回答4:
String fname = ((EditText)findViewById(R.id.txtFirstName)).getText().toString();
String lname = ((EditText)findViewById(R.id.txtLastName)).getText().toString();
((EditText)findViewById(R.id.txtFullName)).setText(fname + " "+lname);
回答5:
Place the following after the setContentView() method.
final EditText edit = (EditText) findViewById(R.id.Your_Edit_ID);
String emailString = (String) edit.getText().toString();
Log.d("email",emailString);
来源：https://stackoverflow.com/questions/1974489/how-to-get-text-from-edittext