Android Basic Class Code

Simple Android Application

first.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter First Number"
        android:layout_marginTop="10dp"
        android:id="@+id/firstnumber"
        android:layout_marginRight="20dp"
        android:inputType="number"
        android:layout_marginLeft="20dp"
        android:padding="20dp" />

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="20dp"
        android:id="@+id/secondnumber"
        android:inputType="number"
        android:hint="Enter Second Number"
        android:padding="20dp"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Add Me"
        android:id="@+id/addbutton"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="10dp"
        android:background="@color/darkyellow"
        android:textColor="@color/white"
        android:padding="20dp"
        android:textAllCaps="false"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Subtract Me"
        android:id="@+id/subbutton"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="10dp"
        android:background="@color/darkyellow"
        android:textColor="@color/white"
        android:padding="20dp"
        android:textAllCaps="false"/>

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Multiply Me"
        android:id="@+id/mulbutton"
        android:layout_marginRight="20dp"
        android:layout_marginLeft="20dp"
        android:layout_marginTop="10dp"
        android:background="@color/darkyellow"
        android:textColor="@color/white"
        android:padding="20dp"
        android:textAllCaps="false"/>

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Dummy Result"
        android:padding="20dp"
        android:id="@+id/resultdata"
        android:textSize="30sp"
        android:layout_marginTop="30dp"
        android:layout_gravity="center"/>

</LinearLayout>

MainActivity.java

package com.example.piyushapp;

import androidx.annotation.Nullable;
import androidx.appcompat.app.AlertDialog;
import androidx.appcompat.app.AppCompatActivity;

import android.content.DialogInterface;
import android.os.Bundle;
import android.util.Log;
import android.view.Gravity;
import android.view.View;
import android.webkit.WebView;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    private EditText t1, t2;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.first);
        t1 = findViewById(R.id.firstnumber);
        t2 = findViewById(R.id.secondnumber);
        Button b1 = findViewById(R.id.addbutton);
        Button b2 = findViewById(R.id.subbutton);
        Button b3 = findViewById(R.id.mulbutton);

        final TextView tv = findViewById(R.id.resultdata);

        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                //u can write logic here
                //get the values from edittext
                String a = t1.getText().toString();
                String b = t2.getText().toString();
                //convert string into integer
                int i = Integer.parseInt(a);
                int j = Integer.parseInt(b);
                int result = i + j;
                //Log.e("result",String.valueOf(result));
                //Toast.makeText(MainActivity.this,
                String.valueOf(result),Toast.LENGTH_LONG).show();

               /* AlertDialog.Builder ab = new 
                AlertDialog.Builder(MainActivity.this);
                ab.setTitle("Result Here");
                ab.setIcon(R.mipmap.ic_launcher_round);
                ab.setMessage(String.valueOf(result));
                ab.setCancelable(false);

                ab.setPositiveButton("Yes", new 
                DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
                ab.setNegativeButton("No", 
                new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
                ab.setNeutralButton("Cancel", 
                 new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                    }
                });
                ab.show();
*/

                tv.setText(String.valueOf(result));
            }
        });

        b2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String a = t1.getText().toString();
                String b = t2.getText().toString();
                int i = Integer.parseInt(a);
                int j = Integer.parseInt(b);
                int result = i - j;
                tv.setText(String.valueOf(result));
            }
        });

        b3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String a = t1.getText().toString();
                String b = t2.getText().toString();
                int i = Integer.parseInt(a);
                int j = Integer.parseInt(b);
                int result = i * j;
                tv.setText(String.valueOf(result));
            }
        });

    }


}

color.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <color name="colorPrimary">#6200EE</color>
    <color name="colorPrimaryDark">#3700B3</color>
    <color name="colorAccent">#AC840B</color>

    <color name="purple">#A1049C</color>
    <color name="white">#fff</color>
    <color name="darkyellow">#CDA815</color>
</resources>