How To Develop A Simple EMI Calculator Using Android Studio

Introduction

Android is one of the most popular operating systems for mobile. In this article, I will show you how to create a Simple EMI Calculator Android application using Android Studio.

Requirements

• Android Studio version 2.3.3
• Little bit XML and JAVA knowledge.
• Android Emulator (or) Android mobile
• Download link (Android Studio)

Steps to be followed

 These steps are required to create a simple EMI Calculator Android application using Android Studio and I have included the source code below.

Step 1

Open Android Studio and Start a New Android Studio Project.

 

Step 2

You can choose your application name and choose where your project is stored on the location. If you wish to use C++ for coding the project, mark the "Include C++ support", and click "Next" button.



Now, select the version of Android and select the target Android devices.

 

Step 3

Now, add the activity and click "Next" button.



Add Activity name and click "Finish".

 

Formula

Here’s the formula to calculate EMI,


where,

• E is EMI
• P is Principal Loan Amount
• r is the rate of interest calculated on monthly basis.
• n is loan term/tenure / duration in number of months

Step 4

Go to activity_main.xml. This XML file contains the designing code for an Android app in the activity_main.xml,



The XML code given below.

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    tools:context="abu.emicalculator.MainActivity"
    android:layout_height="match_parent">
    <android.support.v4.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior">
        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="match_parent"
            android:layout_marginTop="?attr/actionBarSize"
            android:orientation="vertical"
            android:paddingLeft="20dp"
            android:paddingRight="20dp"
            android:paddingTop="10dp">

            <android.support.design.widget.TextInputLayout
                android:id="@+id/input_layout_principal"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <EditText
                    android:id="@+id/principal"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:singleLine="true"
                    android:inputType="number"
                    android:digits="0123456789."
                    android:hint="@string/hint_principal" />

            </android.support.design.widget.TextInputLayout>


            <android.support.design.widget.TextInputLayout
                android:id="@+id/input_layout_interest"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <EditText
                    android:id="@+id/interest"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:singleLine="true"
                    android:inputType="number"
                    android:digits="0123456789."
                    android:hint="@string/hint_interest" />

            </android.support.design.widget.TextInputLayout>

            <android.support.design.widget.TextInputLayout
                android:id="@+id/input_layout_tenure"
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <EditText
                    android:id="@+id/years"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:inputType="number"
                    android:digits="0123456789."
                    android:hint="@string/hint_years" />
            </android.support.design.widget.TextInputLayout>


            <Button android:id="@+id/btn_calculate2"
                android:layout_width="fill_parent"
                android:layout_height="wrap_content"
                android:text="Calculate"
                android:background="@color/colorPrimary"
                android:layout_marginTop="40dp"
                android:textColor="@android:color/white"/>


            <android.support.design.widget.TextInputLayout
                android:id="@+id/input_layout_emi"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="40dp">

                <EditText
                    android:id="@+id/emi"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:maxEms="0"
                    android:inputType="number"
                    android:hint="@string/hint_emi" />
            </android.support.design.widget.TextInputLayout>

            <android.support.design.widget.TextInputLayout
                android:id="@+id/input_layout_total_Interest"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_marginTop="10dp">

                <EditText
                    android:id="@+id/interest_total"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"

                    android:inputType="number"
                    android:hint="@string/hint_interest_total" />
            </android.support.design.widget.TextInputLayout>

        </LinearLayout>
    </android.support.v4.widget.NestedScrollView>

</android.support.design.widget.CoordinatorLayout>

Step 5

Go to (gradle scripts ⇒ build.gradle(moduleapp). And, add the below code.



compile 'com.android.support:appcompat-v7:23.4.0'
compile 'com.android.support:design:23.1.0' 

Step 6

Go to (App ⇒ Res ⇒values⇒String.xml).



The string XML Code Given Below

<resources>
    <string name="app_name">EMI Calculator</string>
    <string name="hint_principal">Principal Amount ₹</string>
    <string name="hint_interest">Interest rate per Year %</string>
    <string name="hint_years">How Many Years</string>
    <string name="hint_emi">EMI ₹</string>
    <string name="hint_interest_total">Total Interest for Loan ₹</string>
</resources>

Step 7

Go to Main Activity.java. This Java program is the back-end language for Android. The Java code is given below.

package abu.emicalculator;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.text.TextUtils;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;


public class MainActivity extends AppCompatActivity {

    Button emiCalcBtn;

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

        final EditText P = (EditText)findViewById(R.id.principal);
        final EditText I = (EditText)findViewById(R.id.interest);
        final EditText Y = (EditText)findViewById(R.id.years);
        final EditText TI = (EditText)findViewById(R.id.interest_total);




        final EditText result = (EditText)findViewById(R.id.emi) ;


        emiCalcBtn = (Button) findViewById(R.id.btn_calculate2);

        emiCalcBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                String st1 = P.getText().toString();
                String st2 = I.getText().toString();
                String st3 = Y.getText().toString();

                if (TextUtils.isEmpty(st1)) {
                    P.setError("Enter Prncipal Amount");
                    P.requestFocus();
                    return;
                }

                if (TextUtils.isEmpty(st2)) {
                    I.setError("Enter Interest Rate");
                    I.requestFocus();
                    return;
                }

                if (TextUtils.isEmpty(st3)) {
                    Y.setError("Enter Years");
                    Y.requestFocus();
                    return;
                }

                float p = Float.parseFloat(st1);
                float i = Float.parseFloat(st2);
                float y = Float.parseFloat(st3);

                float Principal = calPric(p);

                float Rate = calInt(i);

                float Months = calMonth(y);

                float Dvdnt = calDvdnt( Rate, Months);

                float FD = calFinalDvdnt (Principal, Rate, Dvdnt);

                float D = calDivider(Dvdnt);

                float emi = calEmi(FD, D);

                float TA = calTa (emi, Months);

                float ti = calTotalInt(TA, Principal);



                result.setText(String.valueOf(emi));




                TI.setText(String.valueOf(ti));

            }
        });
    }

    public  float calPric(float p) {

        return (float) (p);

    }

    public  float calInt(float i) {

        return (float) (i/12/100);

    }

    public  float calMonth(float y) {

        return (float) (y * 12);

    }

    public  float calDvdnt(float Rate, float Months) {

        return (float) (Math.pow(1+Rate, Months));

    }

    public  float calFinalDvdnt(float Principal, float Rate, float Dvdnt) {

        return (float) (Principal * Rate * Dvdnt);

    }

    public  float calDivider(float Dvdnt) {

        return (float) (Dvdnt-1);

    }

    public  float calEmi(float FD, Float D) {

        return (float) (FD/D);

    }

    public  float calTa(float emi, Float Months) {

        return (float) (emi*Months);

    }

    public  float calTotalInt(float TA, float Principal) {

        return (float) (TA - Principal);

    }
}

Step 8

Now, either go to menu bar and click "Make project" or press ctrl+f9 to debug the error.



Step 9

Then, click Run button or press shift+f10 to run the project. Select the "virtual machine" option and click OK.

Conclusion

We have successfully created Simple EMI Calculator app for Android using Android Studio.