How can I check the system version of Android?

Example how to use it:

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.GINGERBREAD) {
     // only for gingerbread and newer versions
}

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Check android.os.Build.VERSION.

CODENAME: The current development codename, or the string "REL" if this is a release build. INCREMENTAL: The internal value used by the underlying source control to represent this build. RELEASE: The user-visible version string.

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Build.Version is the place go to for this data. Here is a code snippet for how to format it.

public String getAndroidVersion() {
    String release = Build.VERSION.RELEASE;
    int sdkVersion = Build.VERSION.SDK_INT;
    return "Android SDK: " + sdkVersion + " (" + release +")";
}

Looks like this "Android SDK: 19 (4.4.4)"

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For checking device version which is greater than or equal to Marshmallow ,use this code.

if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M){

    }

for ckecking others just change the VERSION_CODES like, K for kitkat, L for loolipop N for Nougat and so on...

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Build.VERSION.RELEASE;

That will give you the actual numbers of your version; aka 2.3.3 or 2.2. The problem with using Build.VERSION.SDK_INT is if you have a rooted phone or custom rom, you could have a none standard OS (aka my android is running 2.3.5) and that will return a null when using Build.VERSION.SDK_INT so Build.VERSION.RELEASE will work no matter what!

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You can find out the Android version looking at Build.VERSION.

The documentation recommends you check Build.VERSION.SDK_INT against the values in Build.VERSION_CODES.

This is fine as long as you realise that Build.VERSION.SDK_INT was only introduced in API Level 4, which is to say Android 1.6 (Donut). So this won't affect you, but if you did want your app to run on Android 1.5 or earlier then you would have to use the deprecated Build.VERSION.SDK instead.

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I can't comment on the answers, but there is a huge mistake in Kaushik's answer: SDK_INT is not the same as system version but actually refers to API Level.

if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.ICE_CREAM_SANDWICH){
    //this code will be executed on devices running ICS or later
}

The value Build.VERSION_CODES.ICE_CREAM_SANDWICH equals 14. 14 is the API level of Ice Cream Sandwich, while the system version is 4.0. So if you write 4.0, your code will be executed on all devices starting from Donut, because 4 is the API level of Donut (Build.VERSION_CODES.DONUT equals 4).

if(Build.VERSION.SDK_INT >= 4.0){
    //this code will be executed on devices running on DONUT (NOT ICS) or later
}

This example is a reason why using 'magic number' is a bad habit.

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Be aware that Build.VERSION.SDK_INT isn't reliable, it's mentioned by @Falcon165o and recently I ran into that one too.

So to get the String data (based on Android version list) of currently installed android, I made a code like this:

Java

//Current Android version data
public static String currentVersion(){
    double release=Double.parseDouble(Build.VERSION.RELEASE.replaceAll("(\\d+[.]\\d+)(.*)","$1"));
    String codeName="Unsupported";//below Jelly Bean
    if(release >= 4.1 && release < 4.4) codeName = "Jelly Bean";
    else if(release < 5)   codeName="Kit Kat";
    else if(release < 6)   codeName="Lollipop";
    else if(release < 7)   codeName="Marshmallow";
    else if(release < 8)   codeName="Nougat";
    else if(release < 9)   codeName="Oreo";
    else if(release < 10)  codeName="Pie";
    else if(release >= 10) codeName="Android "+((int)release);//since API 29 no more candy code names
    return codeName+" v"+release+", API Level: "+Build.VERSION.SDK_INT;
}

Kotlin

fun currentVersion(): String {
    val release = java.lang.Double.parseDouble(java.lang.String(Build.VERSION.RELEASE).replaceAll("(\\d+[.]\\d+)(.*)", "$1"))
    var codeName = "Unsupported"//below Jelly Bean
    if (release >= 4.1 && release < 4.4)  codeName = "Jelly Bean"
    else if (release < 5)   codeName = "Kit Kat"
    else if (release < 6)   codeName = "Lollipop"
    else if (release < 7)   codeName = "Marshmallow"
    else if (release < 8)   codeName = "Nougat"
    else if (release < 9)   codeName = "Oreo"
    else if (release < 10)  codeName = "Pie"
    else if (release >= 10) codeName = "Android "+(release.toInt())//since API 29 no more candy code names
    return codeName + " v" + release + ", API Level: " + Build.VERSION.SDK_INT
}

Example of an output it produce:

Marshmallow v6.0, API Level: 23

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For example, a feature only works for api21 up the following we fix bugs in api21 down

    if(Build.VERSION.SDK_INT >= 21) {
    //only api 21 above
    }else{
   //only api 21 down
    }

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if (Build.VERSION.SDK_INT >= ApiHelper.VERSION_CODES.HONEYCOMB_MR2) {
//do anything you  like.
}

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Use This method:

 public static String getAndroidVersion() {
        String versionName = "";

        try {
             versionName = String.valueOf(Build.VERSION.RELEASE);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return versionName;
    }

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use this class

import android.os.Build;

/**
 * Created by MOMANI on 2016/04/14.
 */
public class AndroidVersionUtil {
    public static int getApiVersion() {
        return android.os.Build.VERSION.SDK_INT;
    }

    public static boolean isApiVersionGraterOrEqual(int thisVersion) {
        return android.os.Build.VERSION.SDK_INT >= thisVersion;
    }
}

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Given you have bash on your android device, you can use this bash function :

function androidCodeName {
    androidRelease=$(getprop ro.build.version.release)
    androidCodeName=$(getprop ro.build.version.codename)

    # Time "androidRelease" x10 to test it as an integer
    case $androidRelease in
        [0-9].[0-9]|[0-9].[0-9].|[0-9].[0-9].[0-9])  androidRelease=$(echo $androidRelease | cut -d. -f1-2 | tr -d .);;
        [0-9].) androidRelease=$(echo $androidRelease | sed 's/\./0/');;
        [0-9]) androidRelease+="0";;
    esac

    [ -n "$androidRelease" ] && [ $androidCodeName = REL ] && {
    # Do not use "androidCodeName" when it equals to "REL" but infer it from "androidRelease"
        androidCodeName=""
        case $androidRelease in
        10) androidCodeName+=NoCodename;;
        11) androidCodeName+="Petit Four";;
        15) androidCodeName+=Cupcake;;
        20|21) androidCodeName+=Eclair;;
        22) androidCodeName+=FroYo;;
        23) androidCodeName+=Gingerbread;;
        30|31|32) androidCodeName+=Honeycomb;;
        40) androidCodeName+="Ice Cream Sandwich";;
        41|42|43) androidCodeName+="Jelly Bean";;
        44) androidCodeName+=KitKat;;
        50|51) androidCodeName+=Lollipop;;
        60) androidCodeName+=Marshmallow;;
        70|71) androidCodeName+=Nougat;;
        80|81) androidCodeName+=Oreo;;
        90) androidCodeName+=Pie;;
        100) androidCodeName+=ToBeReleased;;
        *) androidCodeName=unknown;;
        esac
    }
    echo $androidCodeName
}

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According to Android documentation:

Build.VERSION.RELEASE – "The user-visible version string. E.g., "1.0" or "3.4b5" or "bananas""

In order to get a plain Android version (2.3, 5.1, 12.0, etc) I use this function:

private fun getVersion(): Float {
    val release = Build.VERSION.RELEASE
    val parsedVersion = "\\d+(\\.\\d+)?".toRegex()
        .find(release)?.value
    if (parsedVersion.isNullOrBlank()) return 0f
    return try {
        parsedVersion.toFloat()
    } catch (e: Exception) {
        0f
    }
}

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