Curruncy Converter

How to USE web service to build Currency converter app-android

1.Add OKHTTP dependency to your build.gradle and sync project.

implementation 'com.squareup.okhttp:okhttp:2.5.0'

2.Design your Currency app view

XML file is mentioned below and copy it to activity.main.xml file.

<?xml version="1.0" encoding="utf-8"?>

<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"

    tools:context=".MainActivity">




    <RelativeLayout

        android:id="@+id/relativeLayout"

        android:layout_width="match_parent"

        android:layout_height="485dp"




        android:layout_alignParentEnd="true"

        android:layout_alignParentBottom="true"

        android:layout_marginEnd="0dp"

        android:layout_marginBottom="-53dp"

        android:background="@android:color/holo_blue_dark"

        app:layout_constraintEnd_toEndOf="parent"

        app:layout_constraintHorizontal_bias="0.0"

        app:layout_constraintStart_toStartOf="parent"

        tools:layout_editor_absoluteY="197dp">




        <LinearLayout

            android:layout_width="183dp"

            android:layout_height="wrap_content"

            android:layout_alignParentStart="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentTop="true"

            android:layout_marginStart="0dp"

            android:layout_marginLeft="0dp"

            android:layout_marginTop="58dp"

            android:orientation="vertical">




            <TextView

                android:id="@+id/textView"

                android:layout_width="157dp"

                android:layout_height="wrap_content"

                android:text="From Currency"

                android:textColor="@android:color/black"

                android:textSize="18sp"

                android:textStyle="bold"

                tools:layout_marginLeft="5dp" />

        </LinearLayout>




        <LinearLayout

            android:layout_width="183dp"

            android:layout_height="wrap_content"

            android:layout_alignParentStart="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentTop="true"

            android:layout_marginStart="0dp"

            android:layout_marginLeft="0dp"

            android:layout_marginTop="87dp"

            android:orientation="vertical">




            <TextView

                android:id="@+id/textView5"

                android:layout_width="183dp"

                android:layout_height="match_parent"

                android:text="To Currency"

                android:textColor="@android:color/black"

                android:textSize="18sp"

                android:textStyle="bold"

                tools:layout_marginLeft="5dp" />

        </LinearLayout>




        <LinearLayout

            android:layout_width="match_parent"

            android:layout_height="132dp"

            android:layout_alignParentStart="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentBottom="true"

            android:layout_marginStart="0dp"

            android:layout_marginLeft="0dp"

            android:layout_marginBottom="225dp"

            android:orientation="vertical">




            <TextView

                android:id="@+id/textView6"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"




                android:text="Enter Exchange amout"

                android:textColor="@android:color/black"

                android:textSize="14sp"

                android:textStyle="bold" />




            <EditText

                android:id="@+id/editText"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"




                android:ems="10"

                android:inputType="numberDecimal" />




            <TextView

                android:id="@+id/textView8"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:text="Converted Amount"

                android:textColor="@android:color/black"

                android:textSize="14sp"

                android:textStyle="bold" />




            <EditText

                android:id="@+id/editText4"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:ems="10"

                android:inputType="numberDecimal" />




        </LinearLayout>




        <LinearLayout

            android:layout_width="171dp"

            android:layout_height="wrap_content"

            android:layout_alignParentStart="true"

            android:layout_alignParentLeft="true"

            android:layout_alignParentBottom="true"

            android:layout_marginStart="186dp"

            android:layout_marginLeft="186dp"

            android:layout_marginBottom="147dp"

            android:orientation="vertical">




            <Button

                android:id="@+id/button"

                android:layout_width="match_parent"

                android:layout_height="wrap_content"

                android:text="Calculate"

                android:textColor="@android:color/white"

                android:background="@color/black" />

        </LinearLayout>




        <EditText

            android:id="@+id/editText5"

            android:layout_width="400dp"

            android:layout_height="wrap_content"

            android:layout_alignParentStart="true"

            android:layout_alignParentLeft="true"

            android:layout_marginStart="37dp"

            android:layout_marginLeft="37dp"

            android:layout_marginBottom="-47dp"

            android:ems="10"

            android:inputType="textPersonName"

            android:text="Welcome to Currency Convert"

            android:textColor="@android:color/white"

            android:textSize="24sp"

            android:textStyle="bold" />




        <Spinner

            android:id="@+id/planets_spinner"

            android:layout_width="105dp"

            android:layout_height="wrap_content"

            android:layout_alignBottom="@+id/constraintID1"

            android:layout_alignParentEnd="true"

            android:layout_alignParentRight="true"

            android:layout_marginEnd="60dp"

            android:layout_marginRight="60dp"

            android:layout_marginBottom="-2dp" />




        <android.support.constraint.ConstraintLayout

            android:id="@+id/constraintID1"

            android:layout_width="129dp"

            android:layout_height="24dp"

            android:layout_alignParentTop="true"

            android:layout_alignParentEnd="true"

            android:layout_alignParentRight="true"

            android:layout_marginTop="89dp"

            android:layout_marginEnd="34dp"

            android:layout_marginRight="34dp" />




        <android.support.constraint.ConstraintLayout

            android:layout_width="127dp"

            android:layout_height="27dp"

            android:layout_alignParentTop="true"

            android:layout_alignParentEnd="true"

            android:layout_alignParentRight="true"

            android:layout_marginTop="56dp"

            android:layout_marginEnd="47dp"

            android:layout_marginRight="47dp">




            <TextView

                android:id="@+id/textView14"

                android:layout_width="wrap_content"

                android:layout_height="wrap_content"

                android:layout_marginStart="16dp"

                android:layout_marginLeft="16dp"

                android:text="Euro"

                android:textColor="@android:color/background_dark"

                android:textStyle="bold"

                app:layout_constraintBottom_toBottomOf="parent"

                app:layout_constraintStart_toStartOf="parent"

                app:layout_constraintTop_toTopOf="parent" />

        </android.support.constraint.ConstraintLayout>




    </RelativeLayout>




    <LinearLayout

        android:layout_width="match_parent"

        android:layout_height="251dp"

        android:orientation="vertical"

        tools:layout_editor_absoluteX="8dp"

        tools:layout_editor_absoluteY="8dp"







        >




        <ImageView

            android:layout_width="match_parent"

            android:layout_height="233dp"

            android:src="@drawable/abcd"




            />




    </LinearLayout>




</RelativeLayout>

3.Add below code to your MainActivity.java file

Here we have called the API using web service and get the data as JSON and save it to JSON array and then we are linking the data with the spinner drop down and as the user selected the relevant calculations were done.

we are using web service of

https://api.exchangeratesapi.io/latest

package com.example.cssuser.currencyconvert;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.util.Log;

import android.view.View;

import android.widget.ArrayAdapter;

import android.widget.Button;

import android.widget.EditText;

import android.widget.Spinner;

import android.widget.TextView;

import android.widget.Toast;




import com.squareup.okhttp.Call;

import com.squareup.okhttp.Callback;

import com.squareup.okhttp.OkHttpClient;

import com.squareup.okhttp.Request;

import com.squareup.okhttp.Response;




import org.json.JSONException;

import org.json.JSONObject;




import java.io.IOException;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;




public class MainActivity extends AppCompatActivity {




    List<String> keysList;

    Spinner toCurrency;

    EditText txt;




    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);




        toCurrency = (Spinner)findViewById(R.id.planets_spinner);

        final EditText euroVal = (EditText)findViewById(R.id.editText);

        final Button converter= (Button)findViewById(R.id.button);

        txt = (EditText)findViewById(R.id.editText4);

        try {

            loadConvTypes();

        } catch (IOException e) {

            e.printStackTrace();

        }




        converter.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                if(!euroVal.getText().toString().isEmpty())

                {

                    String toCurr = toCurrency.getSelectedItem().toString();

                    double euroVlaue = Double.valueOf(euroVal.getText().toString());







                    try {

                        convertCurrency(toCurr, euroVlaue);

                    } catch (IOException e) {

                        e.printStackTrace();




                    }

                }

                else

                {

                    Toast.makeText(MainActivity.this, "Please Enter a Value",


 Toast.LENGTH_SHORT).show();

                }




            }

        });




    }




    public void loadConvTypes() throws IOException {




        String url = "https://api.exchangeratesapi.io/latest";




        OkHttpClient client = new OkHttpClient();




        Request request = new Request.Builder()

                .url(url)

                .header("Content-Type", "application/json")

                .build();










        client.newCall(request).enqueue(new Callback() {

            @Override

            public void onFailure(Request request, IOException e) {

                String mMessage = e.getMessage().toString();

                Log.w("failure Response", mMessage);

                Toast.makeText(MainActivity.this, mMessage, Toast.LENGTH_SHORT).show();

            }




            @Override

            public void onResponse(Response response) throws IOException {

                final String mMessage = response.body().string();







                MainActivity.this.runOnUiThread(new Runnable() {

                    @Override

                    public void run() {

                        //Toast.makeText(MainActivity.this, mMessage, Toast.LENGTH_SHORT)


.show();

                        try {

                            JSONObject obj = new JSONObject(mMessage);

                            JSONObject  b = obj.getJSONObject("rates");




                            Iterator keysToCopyIterator = b.keys();

                            keysList = new ArrayList<String>();




                            while(keysToCopyIterator.hasNext()) {




                                String key = (String) keysToCopyIterator.next();




                                keysList.add(key);




                            }







                            ArrayAdapter<String> spinnerArrayAdapter = new


 ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_spinner_item, keysList );

                            toCurrency.setAdapter(spinnerArrayAdapter);
















                        } catch (JSONException e) {

                            e.printStackTrace();

                        }




                    }

                });




            }




        });

    }




    public void convertCurrency(final String toCurr, final double euroVlaue) throws 


IOException {




        String url = "https://api.exchangeratesapi.io/latest";




        OkHttpClient client = new OkHttpClient();




        Request request = new Request.Builder()

                .url(url)

                .header("Content-Type", "application/json")

                .build();










        client.newCall(request).enqueue(new Callback() {

            @Override

            public void onFailure(Request request, IOException e) {

                String mMessage = e.getMessage().toString();

                Log.w("failure Response", mMessage);

                Toast.makeText(MainActivity.this, mMessage, Toast.LENGTH_SHORT).show();

            }




            @Override

            public void onResponse(Response response) throws IOException {




                final String mMessage = response.body().string();

                MainActivity.this.runOnUiThread(new Runnable() {

                    @Override

                    public void run() {

                             try {

                            JSONObject obj = new JSONObject(mMessage);

                            JSONObject  b = obj.getJSONObject("rates");




                            String val = b.getString(toCurr);




                            double output = euroVlaue*Double.valueOf(val);

                            txt.setText(String.valueOf(output));

                        








                        } catch (JSONException e) {

                            e.printStackTrace();

                        }




                    }

                });

            }










        });

    }

}

Thank you !!!!

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