Here is a scenario where I want the user to prevent from adding numbers after point and before of a decimal number.

Example
a)Max char before point 5 and max char after point 2
—Valid numbers
1] 12345
2] 12334.0
3] 23444.55
4] .55
5] 0.5
—Invalid Numbers
1] 43242342
2] 34.45534
etc

Hope you understood what the below code is written for

Solution :
You have to add a TextWatcher for the EditText you want to put this restriction
Here is how you implement the TextWatcher class

public class DecimalTextWacher implements TextWatcher{
	boolean matched=true;
	CharSequence s = null;
	 Matcher m =null;
	@Override
	public void afterTextChanged(Editable s) {
		if(s.length()==0)
			return;
		if(matched == false){
			if(Pattern.matches("\\d{6}", s)||Pattern.matches("\\d{0,5}[.]\\d{3}", s)){
				s.delete(s.length()-1, s.length());
			}else if(Pattern.matches("\\d{6}[.]\\d{0,2}",s)){
				s.delete(5,6);
			}
		}

	}

	@Override
	public void beforeTextChanged(CharSequence s, int start, int count,
			int after) {
		// TODO Auto-generated method stub

	}

	@Override
	public void onTextChanged(CharSequence s, int start, int before, int count) {
		// TODO Auto-generated method stub
		Log.i("char entered", ""+s);

		if(Pattern.matches("\\d{1,5}",s)==true){
			Pattern p = Pattern.compile("\\d{1,5}");
			 m = p.matcher(s);
			 //check weather there is anything after 5 digits - if there it should be only a point
			 if(Pattern.matches("[.]?\\d{0}",s.subSequence(m.regionEnd(),s.length()))){
				 Log.i("matched", ""+s);
				 matched=true;
			 }
		 }else if(Pattern.matches("\\d{1,5}[.]\\d{0,2}",s)==true){
			 Log.i("matched", ""+s);
			 matched=true;
		 }else{
			 matched=false;
		 }

	}

}