SIMPLE CALCULATOR USING ANDROID STUDIO IN JAVA

 

To create a simple calculator  for android using android studio we have to do xml design first.Focus 

on edit text section android:inputType=""

inside quotation if we use just  "number" we cannot have float numbers as input. so we have used numberDecimal.

also for use minus numbers as input  as example (-8)  addition 9= 1

we have used   android:inputType="numberDecimal|numberSigned"

activity_main.xml  :

<?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="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    android:padding="10dp"
    tools:context=".MainActivity">

   <TextView
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
        android:text="simple calculator"
         android:textStyle="italic"
      android:textSize="20sp"
       android:layout_gravity="bottom"/>
   <EditText
       android:id="@+id/editTextId1"
       android:layout_width="200dp"
       android:layout_height="50dp"
       android:textSize="20sp"
       android:textStyle="bold"
      android:hint="@string/editText1"
      android:inputType="numberDecimal|numberSigned"
      android:backgroundTint="#9C27B0"
      android:textCursorDrawable="@null"/>
   <EditText
       android:id="@+id/editTextId2"
       android:layout_width="200dp"
       android:layout_height="50dp"
      android:textSize="20sp"
      android:textStyle="bold"
      android:hint="@string/editText2"
      android:inputType="numberDecimal|numberSigned"
      android:backgroundTint="#E91E63"
      android:textCursorDrawable="@null"/>



   <Button
       android:id="@+id/addButtonId"
       android:text="@string/add_text"
       android:textStyle="bold"
       android:textSize="20sp"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       />
   <Button
       android:id="@+id/subButtonId"
       android:text="@string/sub_text"
       android:textStyle="bold"
       android:textSize="20sp"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       />


   <Button
       android:id="@+id/mulButtonId"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:textStyle="bold"
      android:textSize="20sp"
      android:text="@string/mul_text"/>
   <Button
       android:id="@+id/divButtonId"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:textStyle="bold"
       android:textSize="20sp"
       android:text="@string/div_text"/>



   <TextView
   android:id="@+id/resultTextViewId"
   android:textSize="20sp"
   android:textStyle="bold"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"/>

</LinearLayout>

for  names we have to set string file

string.xml:

<resources>
    <string name="app_name">Basic calculator</string>
    <string name="editText1">Enter number 1</string>
    <string name="editText2">Enter number 2</string>
    <string name="add_text">add(+)</string>
    <string name="sub_text">sub(-)</string>
    <string name="mul_text">mul(*)</string>
    <string name="div_text">div(/)</string>
</resources>

for calculation functionality we have to do java code

MainActivity.java:

package com.example.attendanceapp;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

private EditText editText1,editText2;
private Button addButton,subButton,mulButton,divButton;
private TextView resultTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        editText1=(EditText) findViewById(R.id.editTextId1);
        editText2=(EditText) findViewById(R.id.editTextId2);
        addButton=(Button) findViewById(R.id.addButtonId);
        subButton=(Button) findViewById(R.id.subButtonId);
        mulButton=(Button) findViewById(R.id.mulButtonId);
        divButton=(Button) findViewById(R.id.divButtonId);
        resultTextView=(TextView) findViewById(R.id.resultTextViewId);



            addButton.setOnClickListener(this);
            subButton.setOnClickListener(this);
            mulButton.setOnClickListener(this);
            divButton.setOnClickListener(this);
    }





@Override
    public void onClick(View v){

        String number1 = editText1.getText().toString();
        String number2 = editText2.getText().toString();
        float num1 = Float.parseFloat(number1);
        float num2 = Float.parseFloat(number2);


        {
            if (v.getId() == R.id.addButtonId) {
                float sum = num1 + num2;
                resultTextView.setText("Result:" + sum);}
            if (v.getId() == R.id.subButtonId) {
                float sub = num1 - num2;
                resultTextView.setText("Result:" + sub);
            }

                if (v.getId() == R.id.mulButtonId) {
                    float sum = num1 * num2;
                    resultTextView.setText("Result:" + sum);
                }
                {
                    if (v.getId() == R.id.divButtonId) {
                        float sum = num1 / num2;
                        resultTextView.setText("Result:" + sum);
                    }


                }
            }
       }}

after installing the app 

for better quality

https://youtube.com/shorts/Qn5oQsDULek?si=-RYI9zb6uo2LdSYR