In this tutorial I’ll provide you with an Android Translation App example program. I’ll use the translation web service I built in parts 4, 5 and 6 of my web services video tutorial. I’ll also show how to parse JSON data in an Android app.

Everything has been kept as easy to make as possible and all of the code follows the video below with many comments.

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Code From the Video

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.newthinktank.derekbanas.translation" >

    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MyActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_my.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context=".MyActivity">

    <EditText
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/editText"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true" />

    <Button
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Translate"
        android:id="@+id/button"
        android:layout_below="@+id/editText"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:onClick="onTranslateClick"/>

    <TextView
        android:id="@+id/translationTextView"
        android:text="@string/translation_text_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:layout_marginTop="94dp" />

</RelativeLayout>

MyActivity.java

package com.newthinktank.derekbanas.translation;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.params.BasicHttpParams;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.net.MalformedURLException;

public class MyActivity extends Activity {

    EditText translateEditText;

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

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.my, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    // Calls for the AsyncTask to execute when the translate button is clicked
    public void onTranslateClick(View view) {

        EditText translateEditText = (EditText) findViewById(R.id.editText);

        // If the user entered words to translate then get the JSON data
        if(!isEmpty(translateEditText)){

            Toast.makeText(this, "Getting Translations",
                    Toast.LENGTH_LONG).show();

            // Calls for the method doInBackground to execute
            new SaveTheFeed().execute();

        } else {

            // Post an error message if they didn't enter words
            Toast.makeText(this, "Enter Words to Translate",
                    Toast.LENGTH_SHORT).show();

        }

    }

    // Check if the user entered words to translate
    // Returns false if not empty
    protected boolean isEmpty(EditText editText){

        // Get the text in the EditText convert it into a string, delete whitespace
        // and check length
        return editText.getText().toString().trim().length() == 0;

    }

    // Allows you to perform background operations without locking up the user interface
    // until they are finished
    // The void part is stating that it doesn't receive parameters, it doesn't monitor progress
    // and it won't pass a result to onPostExecute
    class SaveTheFeed extends AsyncTask<Void, Void, Void>{

        // Holds JSON data in String format
        String jsonString = "";

        // Will hold the translations that will be displayed on the screen
        String result = "";

        // Everything that should execute in the background goes here
        // You cannot edit the user interface from this method
        @Override
        protected Void doInBackground(Void... voids) {

            // Get access to the EditText so we can get the text in it
            EditText translateEditText = (EditText) findViewById(R.id.editText);

            // Get the text from EditText
            String wordsToTranslate = translateEditText.getText().toString();

            // Replace spaces in the String that was entered with + so they can be passed
            // in a URL
            wordsToTranslate = wordsToTranslate.replace(" ", "+");

            // Client used to grab data from a provided URL
            DefaultHttpClient httpClient = new DefaultHttpClient(new BasicHttpParams());

            // Provide the URL for the post request
            HttpPost httpPost = new HttpPost("http://newjustin.com/translateit.php?action=translations&english_words=" + wordsToTranslate);

            // Define that the data expected is in JSON format
            httpPost.setHeader("Content-type", "application/json");

            // Allows you to input a stream of bytes from the URL
            InputStream inputStream = null;

            try{

                // The client calls for the post request to execute and sends the results back
                HttpResponse response = httpClient.execute(httpPost);

                // Holds the message sent by the response
                HttpEntity entity = response.getEntity();

                // Get the content sent
                inputStream = entity.getContent();

                // A BufferedReader is used because it is efficient
                // The InputStreamReader converts the bytes into characters
                // My JSON data is UTF-8 so I read that encoding
                // 8 defines the input buffer size
                BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"), 8);

                // Storing each line of data in a StringBuilder
                StringBuilder sb = new StringBuilder();

                String line = null;

                // readLine reads all characters up to a \n and then stores them
                while((line = reader.readLine()) != null){

                    sb.append(line + "\n");

                }

                // Save the results in a String
                jsonString = sb.toString();

                // Create a JSONObject by passing the JSON data
                JSONObject jObject = new JSONObject(jsonString);

                // Get the Array named translations that contains all the translations
                JSONArray jArray = jObject.getJSONArray("translations");

                // Cycles through every translation in the array
                outputTranslations(jArray);

            } catch (MalformedURLException e) {
                e.printStackTrace();
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
            }

            return null;
        }

        // Called after doInBackground finishes executing
        @Override
        protected void onPostExecute(Void aVoid) {

            // Put the translations in the TextView
            TextView translationTextView = (TextView) findViewById(R.id.translationTextView);

            translationTextView.setText(result);

        }

        protected void outputTranslations(JSONArray jsonArray){

            // Used to get the translation using a key
            String[] languages = {"arabic", "chinese", "danish", "dutch",
                "french", "german", "italian", "portuguese", "russian",
                "spanish"};

            // Save all the translations by getting them with the key
            try{

                for(int i = 0; i < jsonArray.length(); i++){

                    JSONObject translationObject =
                            jsonArray.getJSONObject(i);

                    result = result + languages[i] + " : " +
                            translationObject.getString(languages[i]) + "\n";

                }

            } catch (JSONException e) {
                e.printStackTrace();
            }

        }

    }

}

strings.xml

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

    <string name="app_name">Translation</string>
    <string name="hello_world">Hello world!</string>
    <string name="action_settings">Settings</string>
    <string name="translation_text_view">Enter words above for translation</string>

</resources>