Operating System

Android

In this tutorial we will try to create a Simple Rating Bar using Android. This simple app can used on some application that needed a review system to their quality. Android is a mobile operating system developed by Google. It used in several gadget like smartphone, tablet, and even television. Android is open source to developers who has an interest in developing mobile apps. It also provide an adaptive framework that allow the developer to develop an apps in a simpler way. So let's now do the coding...

Getting Started:

First you will have to download & install the Android Development IDE (Android Studio or Eclipse). Android Studio is an open source development feel free to develop your things.

Here's the link for the Android Studio https://developer.android.com/studio/index.html.

Layout Design

We will now create the design for the application, first to do is to create a resource that we will be using for the design. To create the resource, go to drawable folder then create a new xml file named button_style. Then write these certain block of codes inside the newly created file.

1. <?
   
   xml version=
   
   "1.0"
   
   encoding=
   
   "utf-8"
   
   ?>
   
2. <
   
   selector xmlns:
   
   android=
   
   "http://schemas.android.com/apk/res/android"
   
   >
   
3. <
   
   item>
   
4. <
   
   shape android:
   
   shape=
   
   "rectangle"
   
   >
   
5. <
   
   corners android:
   
   radius=
   
   "15dp"
   
   />
   
6. <
   
   solid android:
   
   color=
   
   "#337AB7"
   
   />
   
7. </
   
   shape>
   
8. </
   
   item>
   
9. </
   
   selector>
   

Now that we're done with the graphic resource we will create then layout of the apps. First locate the layout file called activity_main.xml, this is the default name when create a new activity. Then write these codes inside your layout file.

1. <?
   
   xml version=
   
   "1.0"
   
   encoding=
   
   "utf-8"
   
   ?>
   
2. <
   
   RelativeLayout xmlns:
   
   android=
   
   "http://schemas.android.com/apk/res/android"
   
3. xmlns:
   
   app=
   
   "http://schemas.android.com/apk/res-auto"
   
4. xmlns:
   
   tools=
   
   "http://schemas.android.com/tools"
   
5. android:
   
   layout_width=
   
   "match_parent"
   
6. android:
   
   layout_height=
   
   "match_parent"
   
7. tools:
   
   context=
   
   "com.razormist.simpleratingbar.MainActivity"
   
   >
   
8. 
   
9. 
   
10. <
    
    RatingBar
    
11. android:
    
    id=
    
    "@+id/rb_rate"
    
12. android:
    
    layout_width=
    
    "wrap_content"
    
13. android:
    
    layout_height=
    
    "wrap_content"
    
14. android:
    
    layout_alignParentTop=
    
    "true"
    
15. android:
    
    layout_centerHorizontal=
    
    "true"
    
16. android:
    
    layout_marginTop=
    
    "192dp"
    
17. android:
    
    isIndicator=
    
    "false"
    
18. android:
    
    numStars=
    
    "5"
    
19. android:
    
    rating=
    
    "0"
    
20. android:
    
    stepSize=
    
    "1"
    
    />
    
21. 
    
22. <
    
    TextView
    
23. android:
    
    id=
    
    "@+id/tv_result"
    
24. android:
    
    layout_width=
    
    "wrap_content"
    
25. android:
    
    layout_height=
    
    "wrap_content"
    
26. android:
    
    layout_marginTop=
    
    "42dp"
    
27. android:
    
    layout_alignParentTop=
    
    "true"
    
28. android:
    
    textSize=
    
    "40sp"
    
29. android:
    
    layout_centerHorizontal=
    
    "true"
    
    />
    
30. 
    
31. <
    
    Button
    
    
    
32. android:
    
    id=
    
    "@+id/btn_submit"
    
33. android:
    
    layout_height=
    
    "wrap_content"
    
34. android:
    
    layout_width=
    
    "wrap_content"
    
35. android:
    
    layout_below=
    
    "@id/rb_rate"
    
36. android:
    
    layout_centerInParent=
    
    "true"
    
37. android:
    
    layout_marginTop=
    
    "50dp"
    
38. android:
    
    text=
    
    "Submit"
    
39. android:
    
    background=
    
    "@drawable/button_style"
    
40. android:
    
    textColor=
    
    "#fff"
    
    />
    
41. 
    
42. </
    
    RelativeLayout>
    

Android Manifest File

The Android Manifest file provides essential information about your app to the Android system in which the system must required before running the code. It describe the overall information about the application. It contains some libraries that needed to access the several method within the app.

1. <?
   
   xml version=
   
   "1.0"
   
   encoding=
   
   "utf-8"
   
   ?>
   
2. <
   
   manifest xmlns:
   
   android=
   
   "http://schemas.android.com/apk/res/android"
   
3. package
   
   =
   
   "com.razormist.simpleratingbar"
   
   >
   
4. 
   
5. <
   
   application
   
6. android:
   
   allowBackup=
   
   "true"
   
7. android:
   
   icon=
   
   "@mipmap/ic_launcher"
   
8. android:
   
   label=
   
   "@string/app_name"
   
9. android:
   
   roundIcon=
   
   "@mipmap/ic_launcher_round"
   
10. android:
    
    supportsRtl=
    
    "true"
    
11. android:
    
    theme=
    
    "@Style/AppTheme"
    
    >
    
12. <
    
    activity android:
    
    name=
    
    ".MainActivity"
    
13. android:
    
    configChanges=
    
    "orientation"
    
14. android:
    
    screenOrientation=
    
    "portrait"
    
    >
    
15. <
    
    intent-
    
    filter>
    
16. <
    
    action android:
    
    name=
    
    "android.intent.action.MAIN"
    
    />
    
17. 
    
18. <
    
    category android:
    
    name=
    
    "android.intent.category.LAUNCHER"
    
    />
    
19. </
    
    intent-
    
    filter>
    
20. </
    
    activity>
    
21. </
    
    application>
    
22. 
    
23. </
    
    manifest>
    

The Main Function

This code contains the main function of the application. This code will allow you to select your desire star and prompt some confirmation when the button is clicked. To start with first locate your MainActivity java file and open it, then write these some important variables inside the MainActivity class.

1. private
   
   Button
   
   btn_submit;
   
2. private
   
   TextView tv_result;
   
3. private
   
   RatingBar rb_rate;
   

Then write these several method inside the activity class to make the apps work properly.

1. void
   
   InitializeVariables(
   
   )
   
   {
   
2. rb_rate =
   
   (
   
   RatingBar)
   
   findViewById(
   
   R.id
   
   .rb_rate
   
   )
   
   ;
   
3. btn_submit =
   
   (
   
   Button
   
   )
   
   findViewById(
   
   R.id
   
   .btn_submit
   
   )
   
   ;
   
4. tv_result =
   
   (
   
   TextView)
   
   findViewById(
   
   R.id
   
   .tv_result
   
   )
   
   ;
   
5. }
   
6. 
   
7. void
   
   RatingUpdate(
   
   )
   
   {
   
8. rb_rate.setOnRatingBarChangeListener
   
   (
   
   new
   
   RatingBar.OnRatingBarChangeListener
   
   (
   
   )
   
   {
   
9. @Override
   
10. public
    
    void
    
    onRatingChanged(
    
    RatingBar ratingBar, float
    
    rating, boolean
    
    fromUser)
    
    {
    
11. tv_result.setText
    
    (
    
    "Rating: "
    
    +
    
    String
    
    .valueOf
    
    (
    
    Math
    
    .round
    
    (
    
    rating)
    
    )
    
    )
    
    ;
    
12. 
    
13. }
    
14. }
    
    )
    
    ;
    
15. }
    
16. 
    
17. void
    
    SubmitRating(
    
    )
    
    {
    
18. btn_submit.setOnClickListener
    
    (
    
    new
    
    View
    
    .OnClickListener
    
    (
    
    )
    
    {
    
19. @Override
    
20. public
    
    void
    
    onClick(
    
    View
    
    v)
    
    {
    
21. Toast.makeText
    
    (
    
    MainActivity.this
    
    , "Thanks for the rate"
    
    , Toast.LENGTH_SHORT
    
    )
    
    .show
    
    (
    
    )
    
    ;
    
22. }
    
23. }
    
    )
    
    ;
    
24. }
    

Finally, initialize all the methods inside the onCreate method to run the application.

1. InitializeVariables(
   
   )
   
   ;
   
2. RatingUpdate(
   
   )
   
   ;
   
3. SubmitRating(
   
   )
   
   ;
   

Try to run the app and see if it worked.

There you have it we create a Simple Rating Bar using Android. I hope that this tutorial help you to what you are looking for. For more updates and tutorials just kindly visit this site. Enjoy Coding!!!

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