Check out example codes for "android get sdk version". It will help you in understanding the concepts better.

Code Example 1

if(android.os.Build.VERSION.SDK_INT ==  android.os.Build.VERSION_CODES.LOLLIPOP){
	// Code For Android Version higher equal to LOLLIPOP(21)
} else if(android.os.Build.VERSION.SDK_INT > 21){
	// Code For Android Version higher than LOLLIPOP(21)
} else{
	// Code For Android Version lower than LOLLIPOP(21)
}

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