fibo

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
TextView t1;
Button b1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
t1=findViewById(R.id.tdisplay);
b1=findViewById(R.id.button);
b1.setOnClickListener(new View.OnClickListener() {
@SuppressLint("SetTextI18n")
@Override
public void onClick(View view) {
int n1=0,n2=1,n3,i,count=10;

            for(i=2;i<count;++i)//loop starts from 2 because 0 and 1 are already printed
            {
                n3=n1+n2;

                n1=n2;
                n2=n3;
                t1.setText("Series of first 50 numbers:  "+n3);
            }
        }
    });
}

}

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical" tools:context=".MainActivity">

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <TextView
        android:id="@+id/tans"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1"
        android:text="Ans"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/tdisplay"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight="1" />

</LinearLayout>

<Button
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="80dp"
    android:layout_weight="1"
    android:text="Calculate Fibbonacci"
    android:textAppearance="@style/TextAppearance.AppCompat.Large" />

</LinearLayout>