How to Create Calculator Android App Using Android Studio.

Calculator Android App Using Android Studio.

• Building a Simple Calculator using Android Studio.
• Android Development: Creating a Basic Calculator.
• Create Simple Calculator Android Application.
• How to create a Simple Calculator Application for Android Studio.

MainActivity.java

package com.example.sunny.calculator;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    double input1 = 0, input2 = 0;
    TextView edt1;
    boolean Addition, Subtract, Multiplication, Division, Remainder1, decimal;
    Button btn0, btn1, btn2, btn3, btn4,
            btn5, btn6, btn7, btn8, btn9, btnAdd, btnSub,
            btnMul, btnDivision, btnEqual, btnDel, btnDot, Remainder;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        btn0 = (Button) findViewById(R.id.button0);
        btn1 = (Button) findViewById(R.id.button1);
        btn2 = (Button) findViewById(R.id.button2);
        btn3 = (Button) findViewById(R.id.button3);
        btn4 = (Button) findViewById(R.id.button4);
        btn5 = (Button) findViewById(R.id.button5);
        btn6 = (Button) findViewById(R.id.button6);
        btn7 = (Button) findViewById(R.id.button7);
        btn8 = (Button) findViewById(R.id.button8);
        btn9 = (Button) findViewById(R.id.button9);
        btnDot = (Button) findViewById(R.id.buttonDot);
        btnAdd = (Button) findViewById(R.id.buttonadd);
        btnSub = (Button) findViewById(R.id.buttonsub);
        btnMul = (Button) findViewById(R.id.buttonmul);
        btnDivision = (Button) findViewById(R.id.buttondiv);
        Remainder = (Button) findViewById(R.id.Remainder);
        btnDel = (Button) findViewById(R.id.buttonDl);
        btnEqual = (Button) findViewById(R.id.buttoneql);
        edt1 = (TextView) findViewById(R.id.display);

        btn1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "1");
            }
        });

        btn2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "2");
            }
        });

        btn3.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "3");
            }
        });

        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "4");
            }
        });

        btn5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "5");
            }
        });

        btn6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "6");
            }
        });

        btn7.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "7");
            }
        });

        btn8.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "8");
            }
        });

        btn9.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "9");
            }
        });

        btn0.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText(edt1.getText() + "0");
            }
        });

        btnAdd.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (edt1.getText().length() != 0) {
                    input1 = Float.parseFloat(edt1.getText() + "");
                    Addition = true;
                    decimal = false;
                    edt1.setText(null);
                }
            }
        });

        btnSub.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (edt1.getText().length() != 0) {
                    input1 = Float.parseFloat(edt1.getText() + "");
                    Multiplication = true;
                    decimal = false;
                    edt1.setText(null);
                }
            }
        });

        btnMul.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (edt1.getText().length() != 0) {
                    input1 = Float.parseFloat(edt1.getText() + "");
                    Subtract = true;
                    decimal = false;
                    edt1.setText(null);
                }
            }
        });

        btnDivision.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (edt1.getText().length() != 0) {
                    input1 = Float.parseFloat(edt1.getText() + "");
                    Division = true;
                    decimal = false;
                    edt1.setText(null);
                }
            }
        });

        Remainder.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (edt1.getText().length() != 0) {
                    input1 = Float.parseFloat(edt1.getText() + "");
                    Remainder1 = true;
                    decimal = false;
                    edt1.setText(null);
                }
            }
        });

        btnEqual.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (Addition || Multiplication || Subtract || Division || Remainder1) {
                    input2 = Float.parseFloat(edt1.getText() + "");
                }

                if (Addition) {

                    edt1.setText(input1 + input2 + "");
                    Addition = false;
                }

                if (Multiplication) {
                    edt1.setText(input1 * input2 + "");
                    Multiplication = false;
                }

                if (Subtract) {
                    edt1.setText(input1 - input2 + "");
                    Subtract = false;
                }

                if (Division) {
                    edt1.setText(input1 / input2 + "");
                    Division = false;
                }
                if (Remainder1) {
                    edt1.setText(input1 % input2 + "");
                    Remainder1 = false;
                }
            }
        });

        btnDel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                edt1.setText("");
                input1 = 0;
                input2 = 0;
            }
        });

        btnDot.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (decimal) {
                    //do nothing or you can show the error
                } else {
                    edt1.setText(edt1.getText() + ".");
                    decimal = true;
                }

            }
        });


    }
}

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:background="#ecf0f1"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.3"
        android:orientation="horizontal">

        <TextView
            android:id="@+id/display"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:background="#ecf6f9"
            android:textSize="30sp" />
    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/buttonDl"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/button"
            android:text="Del"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/buttoneql"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/button"
            android:text="="
            android:textColor="#ecf0f1"
            android:textSize="30sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="1"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="2"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button3"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="3"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/buttondiv"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/operator_selector"
            android:text="÷"
            android:textColor="#ecf0f1"
            android:textSize="35dp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="4"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button5"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="5"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button6"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="6"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/buttonsub"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/operator_selector"
            android:text="x"
            android:textColor="#ecf0f1"
            android:textSize="30sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/button7"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="7"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button8"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="8"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button9"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="9"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/buttonmul"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/operator_selector"
            android:text="-"
            android:textColor="#ecf0f1"
            android:textSize="30sp" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_weight="0.2"
        android:orientation="horizontal">

        <Button
            android:id="@+id/buttonDot"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="."
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/button0"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/selector"
            android:text="0"
            android:textColor="#ecf0f1"
            android:textSize="20sp" />

        <Button
            android:id="@+id/Remainder"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/operator_selector"
            android:text="%"
            android:textColor="#ecf0f1"
            android:textSize="30sp" />

        <Button
            android:id="@+id/buttonadd"
            android:layout_width="wrap_content"
            android:layout_height="match_parent"
            android:layout_margin="1dp"
            android:layout_weight="0.25"
            android:background="@drawable/operator_selector"

            android:text="+"
            android:textColor="#ecf0f1"
            android:textSize="30sp" />


    </LinearLayout>

</LinearLayout>

button.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">

    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle"
    android:useLevel="false">

    <solid android:color="#3498db" />
    <corners android:radius="30px"/>

    <padding
        android:left="5dp"
        android:top="5dp"
        android:right="3dp"
        android:bottom="3dp"/>

</shape>

operator_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="false"
        android:state_focused="false">
        <shape
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:shape="rectangle"
            android:useLevel="false">
            <corners android:radius="30px"/>
            <solid android:color="@color/green"/>

            <padding
                android:left="5dp"
                android:top="5dp"
                android:right="3dp"
                android:bottom="3dp"/>
        </shape>
    </item>

    <item android:state_pressed="false"
        android:state_focused="true">
        <shape
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:shape="rectangle"
            android:useLevel="false">
            <corners android:radius="30px"/>
            <solid android:color="@color/operator_btn_clr"/>

            <padding
                android:left="5dp"
                android:top="5dp"
                android:right="3dp"
                android:bottom="3dp"/>
        </shape>
    </item>

    <item android:state_pressed="true"
        android:state_focused="false">
        <shape
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:shape="rectangle"
            android:useLevel="false">
            <corners android:radius="30px"/>
            <solid android:color="@color/operator_btn_clr"/>

            <padding
                android:left="5dp"
                android:top="5dp"
                android:right="3dp"
                android:bottom="3dp"/>
        </shape>
    </item>

</selector>

selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">

    <item android:state_pressed="false"
        android:state_focused="false">

    <shape
        xmlns:android="http://schemas.android.com/apk/res/android"
        android:shape="rectangle"
        android:useLevel="false">
        <corners android:radius="30px"/>
        <solid android:color="@color/btn_clr"/>

        <padding
            android:left="5dp"
            android:top="5dp"
            android:right="3dp"
            android:bottom="3dp"/>
    </shape>
</item>

<item android:state_pressed="false"
android:state_focused="true">
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle"
    android:useLevel="false">
    <corners android:radius="30px"/>
    <solid android:color="@color/selected"/>

    <padding
        android:left="5dp"
        android:top="5dp"
        android:right="3dp"
        android:bottom="3dp"/>
</shape>
</item>

<item android:state_pressed="true"
android:state_focused="false">
<shape
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle"
    android:useLevel="false">
    <corners android:radius="30px"/>
    <solid android:color="@color/selected"/>

    <padding
        android:left="5dp"
        android:top="5dp"
        android:right="3dp"
        android:bottom="3dp"/>
</shape>
</item>

</selector>

OUTPUT

Calculator Android App Using Android Studio.