Develop Reference

Android Studio Kotlin - Onclick listener not being recognized

So this is my first time using Kotlin and Android studio and I really got to say thus far my experience has been horrible. No other language or IDE has put me in the position where I had to do more than hours research to try and make a simple button load the next page and then still being unable to do it.
This is my Login.kt page
and there you can see its having problems with the findviewbyID and setonlclicklistener.
Top of my Activity_login.xml page
The button im trying to create the onclick event for.
Please keep in mind I did try just the normal creation of setonclick for the button but then I didnt seem to recognize that I have a button with the ID of login_btn

change the init button to
val button=findViewById<Button>(R.id.login_btn)

in my case i have removed onclick from xml.
val button : Button = findViewById(R.id.login_btn);
button.setOnClickListener {
}

If no answers above can help you, you can use viewbinding to access your view. I had so many problems while using findViewById as a newbie. Here is the documentation,
https://developer.android.com/topic/libraries/view-binding

how is an object created?

EditText text1;
text1 = (EditText) findViewById(R.id.editText1);
text1.getText().toString();
Hi im new to android programming an need a little help. :) I just want to clarify if text1 is an object? Because it can call a method. But if text1 is an object how come that there is no "new" keyword. Thanks in advance for any response. :)

It is not necessary that all variables do initialization with new keyword.
Like if you write
String s = "";
Your String has been initialized without new keyword.
Same like this EditText is provided initialization in findViewById(). Here findViewById returned Edittext instance.
I suggest you complete Java Tutorial before continue work on Android. Because Android is based on Java language.

EditText is derived from the Super class View. Here findViewById method is returning an an object of the View class. You are explicitly typecasting it to EditText and assigning it to text1. So new is not required. It is being managed in findViewById method. Alternatively you can do this as:
EditText text1;
text1 = new EditText(An instance of Context); //Create an object of Edittext class
Now do whatever with this object text1.

It's me 2 years after, Now I want to answer your question bud. I know you just started and had a dream of creating apps that will be used by others, and guess what? You already achieved that and you can now also create apps not just for android but for IOS since you're using flutter now, you also have your own account on google play store now. Listen Bud, on the first line you declare what type is the text1. on the second line that's where you declare the text1 as an object now, then on the third line you are then using that object's capabilities like getting text. You've learned so much in this journey, and still learning not just in programming but in life.

Use EditText in a DialogFragment to change TextView in Main Activity?

So I'm working on my first real attempt at an Android app, just a simple scorekeeper for softball games. I've got it tallying scores, outs, etc, and right now it just displays "Home" and "Away." I'd like to give users the chance to enter in actual team names. To this effect, I added a custom AlertDialog that pops up with an EditText, so when you hit "OK" it'll update the Home/Away team name.
The problem is I've been Googling this for most of the week and I've not found a single way to actually do this. I've tried tagging the fragment's layout XML so I can find the EditText, but it always gives me a null reference and crashes the app. I added a TextWatcher that presumably watched the fragment's text, but once changed and hit "OK," nothing happened. Tried adding the TextWatch to the fragment, that crashed I think, it was about two hours ago and I'm exhausted.
Really, I think I need a way to have the fragment find the TextView with the team name and change it to the value of the EditText when I positive click, but I don't know how to do that. Or maybe I've seen it and don't understand it, I've only been doing this about two months. I'd post my code, but I deleted out all the stuff that didn't work because it was taking up most of the screen real estate. Any ideas?
EDIT: So I followed advice below on defining views, that found the value of the EditText presumably, but hitting "OK" just made it set the TextView to a blank value. I think this is because the EditText's contents went away as the dialog was closed. Either that or this is all wrong. View dialogname = getActivity().getLayoutInflater().inflate(R.layout.fragment_home, null);
EditText mEtName = (EditText) dialogname.findViewById(R.id.homeName);
View mainAct = getActivity().getLayoutInflater().inflate(R.layout.activity_softball, null);
TextView oTextView = (TextView) mainAct.findViewById(R.id.teamOne);
newName = mEtName.getText().toString();
oTextView.setText(newName)

I think you are doing wrong at time of defining id for EditText. You need to give it dialog reference.
rather than doing
Edittext edittext = (EditText) findViewById(R.id.editText);
do like
Edittext edittext = (EditText) dialog.findViewById(R.id.editText);

Been through this issue a while ago. I created my own class which extended DialogFragment. When I tried to initialize EditText which was in the dialog, I got null like
mEtName = (EditText)dialog.findViewById(R.id.editText);
So, I initialized it in this way and it worked:
#Override
public Dialog onCreateDialog(Bundle savedInstanceState) {
...
View dialogName = getActivity().getLayoutInflater().inflate(R.layout.dialog_name, null);
mEtName = (EditText) dialogName.findViewById(R.id.dialog_etxt_name);
}
Where R.layout.dialog_name is my custom dialog layout.

Change TextView text

I'm trying to change my TextView text from the code.
This is what my xml looks like:
XML:
<TextView
android:id="#+id/textView1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical|center_horizontal" />
And the code:
TextView tv1 = (TextView)findViewById(R.id.textView1);
tv1.setText("Hello");
setContentView(tv1);
I'm getting an error on my device and the application stops.
I tried to show a TextView (not connected to an XML TextView) and it worked.

Your approach is incorrect. I think it will be Null Pointer Exception (next time post log cat)
You need to specify the layout you are using first, before finding views.
Java:
// Specify the layout you are using.
setContentView(R.layout.yourlayout);
// Load and use views afterwards
TextView tv1 = (TextView)findViewById(R.id.textView1);
tv1.setText("Hello");
Kotlin:
// Specify the layout you are using.
setContentView(R.layout.yourlayout)
// Load and use views afterwards
val tv1: TextView = findViewById(R.id.textView1)
tv1.text = "Hello"
Click Here to study exactly you want to know

remove this.. setContentView(tv1);

I got the same problem. My app was stopping too.
Actually, I was writing the code outside of the function/method. So to fix this problem, these lines
TextView tv1 = (TextView)findViewById(R.id.textView1);
tv1.setText("Hello");
must be inside a function/method. (can be user defined)
(I am new to android studio so I don't know the reason behind the problem but I only know how to fix this. Maybe this helps new ones despite this question being 8 years old.)

facing problem while displaying the value of the variable

I have just tried to display the value of the variable but is showing some kind of exception
that is FORCE CLOSE.
the code i have tried is
TextView myTextView = (TextView) findViewById(R.id.result9);
myTextView.setText("your score is " +count);
considered count=0 intially.
Can any one suggest me for this problem
thanks in advance

if myTexyView is in dialog you have to do this:
myTextView = (TextView) dialog.findViewById();
anyway do clean project...this happens sometimes:
in eclipse: project->clean->your project

Seems findViewById() returns null. It means that either there's no widget with id result9 in current layout or your forgot to setContentView().

can please check your xml which one you have set, setContainView() it mast have TextView with "result9" this id.