How to check if my string is equal to null?

Solution:

public static boolean isEmpty(String string) {
    return string == null || string.length() == 0;
}

Usage:

if (isEmpty(string)) {
  // do something
}
Explanation:

As noted above, the || and && operators short circuit. That means as soon as they can determine their value they stop. So if (string == null) is true, the length part does not need to be evaluated, as the expression would always be true. Likewise with &&, where if the left side is false, the expression is always false and need not be evaluated further.

As an additional note, using length is generally a better idea than using .equals. The performance is slightly better (not much), and doesn't require object creation (though most compilers might optimize this out).

Date Function in Java

Getting the current Date-time:

public String getCuurentDateTime(){
DateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
Calendar cal = Calendar.getInstance();
String cal2 = dateFormat.format(cal.getTime());
return cal2;