How to make a Calculator in Android Studio || Simple Calculator In Android Studio || RSM Developer

Simple Calculator In Android Studio 

 Step 1: Creating a new project

• Open a new project.
• We will be working on Empty Activity with language as Java. Leave all other options unchanged.
• You can change the name of the project at your convenience.
• There will be two default files named activity_main.xml and MainActivity.java.

Step 2: Open res -> layout ->activity_main.xml (or) main.xml and add following code:

In this step we open an XML file and add the code :-

<RelativeLayout 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:background="@color/white"
    tools:context=".MainActivity5">


    <LinearLayout

        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_alignParentTop="true"
        android:background="@drawable/bottom_shade"
        android:paddingVertical="16dp"
        android:layout_margin="5dp"
        android:layout_above="@id/logo"
        >
    <TextView
        android:id="@+id/inputText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="right"
        android:paddingRight="20dp"
        android:textColor="#000000"
        android:textSize="20dp"
        android:layout_margin="5dp"
        android:layout_above="@id/outputText"/>


    <TextView
        android:id="@+id/outputText"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="right"
        android:layout_above="@id/buttons_layout"
        android:textColor="@color/teal_200"
        android:layout_margin="5dp"
        android:textSize="25dp" />
    </LinearLayout>

    <TextView
        android:id="@+id/logo"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
       android:text="Bondhu Calculator"
        android:textSize="20sp"
        android:textColor="@color/teal_700"
        android:layout_above="@+id/buttons_layout"
        android:gravity="center"
        />

    <LinearLayout
        android:id="@+id/buttons_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical"
        android:layout_alignParentBottom="true"
        android:background="#F1F1F1"
        android:paddingVertical="16dp"
        >



    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal"
        android:weightSum="4"
        android:padding="5dp"
        >


        <Button
            android:id="@+id/clear_btn"
            android:text="C"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#F44336"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>


        <Button
            android:id="@+id/power_btn"
            android:text="^"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#0D47A1"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/percent_btn"
            android:text="%"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#0D47A1"
            android:layout_weight="1"
            android:onClick="onButtonClicked"
            />



        <Button
            android:id="@+id/division_btn"
            android:text="÷"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#0D47A1"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>
    </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="horizontal"
            android:weightSum="4"
            >

        <Button
            android:id="@+id/btn7"
            android:text="7"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#2196F3"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/btn8"
            android:text="8"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>


        <Button
            android:id="@+id/btn9"
            android:text="9"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/btn_multiply"
            android:text="×"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#00BCD4"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>
    </LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="horizontal"
            android:weightSum="4"
            >

        <Button
            android:id="@+id/btn4"
            android:text="4"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#2196F3"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>


        <Button
            android:id="@+id/btn5"
            android:text="5"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/btn6"

            android:text="6"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/btn_minus"
            android:text="-"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#00BCD4"
            android:layout_weight="1"
            android:onClick="onButtonClicked"/>
</LinearLayout>

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:orientation="horizontal"
            android:weightSum="4"
            >

        <Button
            android:id="@+id/btn1"
            android:text="1"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#2196F3"
            android:onClick="onButtonClicked"
            android:layout_weight="1"
       />

        <Button
            android:id="@+id/btn2"
            android:text="2"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:onClick="onButtonClicked"
            android:layout_weight="1"/>


        <Button
            android:id="@+id/btn3"
            android:text="3"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#009688"
            android:onClick="onButtonClicked"
/>

        <Button
            android:id="@+id/btn_plus"
            android:text="+"
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#00BCD4"
            android:onClick="onButtonClicked"
            android:layout_weight="1"/>

        </LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:gravity="center"
                android:weightSum="3"
                android:orientation="horizontal"
                >

                <Button
                android:id="@+id/btn0"
                android:text="0"
                android:layout_width="72dp"
                android:layout_height="72dp"
                android:textSize="32sp"
                android:textColor="@color/colorWhite"
                app:cornerRadius="36dp"
                style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
                android:layout_margin="12dp"
                    android:backgroundTint="#FF9800"
                    android:layout_weight="1"
                android:onClick="onButtonClicked"/>

        <Button
            android:id="@+id/btn_dot"
            android:text="."
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#FF9800"
            android:onClick="onButtonClicked"
            android:layout_weight="1"
    />

        <Button
            android:id="@+id/btn_equals"
            android:text="="
            android:layout_width="72dp"
            android:layout_height="72dp"
            android:textSize="32sp"
            android:textColor="@color/colorWhite"
            app:cornerRadius="36dp"
            style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
            android:layout_margin="12dp"
            android:backgroundTint="#FF9800"
            android:onClick="onButtonClicked"
            android:layout_weight="1"
         />



    </LinearLayout>

    </LinearLayout>
</RelativeLayout>

Step 3: Create a Custom drawable resource file (Name:bottom_shade) :-Open ->drawable -> bottom_shade.xml  and add following code:
In this step we open an XML file and add the code :-
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
    

    <item>
        <shape android:shape="rectangle" >
            <solid android:color="#004D40" />
            <corners android:radius="10dp" />
        </shape>
    </item>
    
    
    <item
        android:bottom="5dp"
        android:left="5dp"
        android:right="5dp"
        android:top="5dp">
        
        
        <shape android:shape="rectangle" >
            <solid android:color="#D58AB3F3" />
            <corners android:radius="30dp"/>
        </shape>
        
        <shape android:shape="rectangle"  >
             <corners android:radius="0dip" />
             <stroke android:width="0dip" 
                 android:color="#DD1313" />
                 
                    
         </shape>
                 
                     
    </item>

</layer-list>

Step 4: Open Java -> package – > MainActivity.Java and add following code:

In this step we open an Java file and add the code :-

package com.rsmdeveloper.calculator;

import androidx.appcompat.app.AppCompatActivity;

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

/**
 * Created by RSM Developer on 14-03-2023.
 * Follow Facebook : https://www.facebook.com/RSMDeveloper
 * Subscribe Youtube : https://www.youtube.com/@RSMDeveloper
 * Visit Website : https://rsmdeveloper.blogspot.com/
 * Develope Your Creativity With RSM Developer
 **/

public class MainActivity5 extends AppCompatActivity {

//===============================================================
    TextView inputText, outputText;

    private String input, output, newOutput;

    private Button clear_btn,power_btn,percent_btn,division_btn,
            btn7,btn8,btn9,btn4,btn5,btn6,btn1,btn2,btn3,btn0,
            btn_multiply, btn_minus, btn_plus, btn_equals,btn_dot;
    //===============================================================
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main5);

//===============================================================
        inputText = findViewById(R.id.inputText);
        outputText = findViewById(R.id.outputText);

        btn0= findViewById(R.id.btn0);
        btn1 = findViewById(R.id.btn1);
        btn2 = findViewById(R.id.btn2);
        btn3 = findViewById(R.id.btn3);
        btn4 = findViewById(R.id.btn4);
        btn5 = findViewById(R.id.btn5);
        btn6 = findViewById(R.id.btn6);
        btn7 = findViewById(R.id.btn7);
        btn8 = findViewById(R.id.btn8);
        btn9 = findViewById(R.id.btn9);
        btn_plus= findViewById(R.id.btn_plus);
        btn_multiply= findViewById(R.id.btn_multiply);
        division_btn = findViewById(R.id.division_btn);
        btn_minus = findViewById(R.id. btn_minus);
        btn_dot = findViewById(R.id.btn_dot);
        power_btn = findViewById(R.id.power_btn);
        btn_equals = findViewById(R.id.btn_equals);
        percent_btn= findViewById(R.id.percent_btn);
        clear_btn = findViewById(R.id.clear_btn);

    }
    //===============================================================
    public void onButtonClicked(View view) {

        Button button = (Button) view;
        String data = button.getText().toString();
        switch (data) {
            case "C":
                input = null;
                output=null;
                newOutput=null;
                outputText.setText("");
                break;

            case "^":
                solve();
                input += "^";
                break;
            case "*":
                solve();
                input += "*";
                break;

            case "=":
                solve();
                break;

            case "%":
                input += "%";
                double d = Double.parseDouble(inputText.getText().toString()) / 100;
                outputText.setText(String.valueOf(d));
                break;

            default:
                if (input == null) {
                    input = "";
                }
                if (data.equals("+") || data.equals("/") || data.equals("-")) {
                    solve();
                }
                input += data;
        }
        inputText.setText(input);
    }

    private void solve() {
        if (input.split("\\+").length == 2) {
            String numbers[] = input.split("\\+");
            try {
                double d = Double.parseDouble(numbers[0]) + Double.parseDouble(numbers[1]);
                output = Double.toString(d);
                newOutput = cutDecimal(output);
                outputText.setText(newOutput);
                input = d +"";
            }catch (Exception e) {
                outputText.setText(e.getMessage().toString());
            }
        }
        if (input.split("\\*").length == 2) {
            String numbers[] = input.split("\\*");
            try {
                double d = Double.parseDouble(numbers[0]) * Double.parseDouble(numbers[1]);
                output = Double.toString(d);
                newOutput = cutDecimal(output);
                outputText.setText(newOutput);
                input = d +"";
            }catch (Exception e){
                outputText.setText(e.getMessage().toString());
            }
        }
        if (input.split("\\/").length == 2) {
            String numbers[] = input.split("\\/");
            try {
                double d = Double.parseDouble(numbers[0]) / Double.parseDouble(numbers[1]);
                output = Double.toString(d);
                newOutput = cutDecimal(output);
                outputText.setText(newOutput);
                input = d +"";
            }catch (Exception e){
                outputText.setText(e.getMessage().toString());
            }
        }
        if (input.split("\\^").length == 2) {
            String numbers[] = input.split("\\^");
            try {
                double d = Math.pow(Double.parseDouble(numbers[0]), Double.parseDouble(numbers[1]));
                output = Double.toString(d);
                newOutput = cutDecimal(output);
                outputText.setText(newOutput);
                input = d +"";
            }catch (Exception e){
                outputText.setText(e.getMessage().toString());
            }
        }
        if (input.split("\\-").length == 2) {
            String numbers[] = input.split("\\-");
            try {
                if (Double.parseDouble(numbers[0]) < Double.parseDouble(numbers[1])){
                    double d = Double.parseDouble(numbers[1]) - Double.parseDouble(numbers[0]);
                    output = Double.toString(d);
                    newOutput = cutDecimal(output);
                    outputText.setText("-" + newOutput);
                    input = d +"";
                }
                else {
                    double d = Double.parseDouble(numbers[0]) - Double.parseDouble(numbers[1]);
                    output = Double.toString(d);
                    newOutput = cutDecimal(output);
                    outputText.setText(newOutput);
                    input = d + "";
                }
            }catch (Exception e){
                outputText.setText(e.getMessage().toString());
            }
        }
        //===============================================================
    }
    private String cutDecimal(String number){
        String n [] = number.split("\\.");
        if (n.length >1){
            if (n[1].equals("0")){
                number = n[0];
            }
        }
        return number;
    }//===============================================================

}

Output:
Now run the App and you will see main topics and sub-topics listed.....
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