Given a string, the task is to find its corresponding datatype using regular expression in java.
We can broadly classify all data types into following types:
- Integer: Numeric datatypes like byte, short, int, long take the form of an Integer object.
- Double: Decimal datatypes like float and double take the form of Double object.
- Date: Date in any format (like dd-mm-yyyy or dd/mm/yyyy) is a part of java.util.Date
- String: All remaining inputs come under the String type.
Note: Character inputs and boolean values will also be considered as string.
Examples:
Input: “56.73”
Output: java.lang.Double
Explanation: 56.73 is of float data type which are part of java.lang.Double
Input: “true”
Output: java.lang.String
Explanation: Here true is considered as a regular string which is a part of java.lang.String
Approach:
- Take input in the form of a string.
- Now if the input contains only digits, it is an Integer object. If it contains numbers with a decimal point, it is a Double-object. If the input is in the form of a Date, we print it as java.util.Date object. Else, we say that the input is a String object which may contain alphanumeric and special characters.
Below is the implementation of the above approach:
Java
public class GFG { // method stub public static void main(String[] arg) { String input = "56.73"; String dataType = null; // checking for Integer if (input.matches("\\d+")) { dataType = "java.lang.Integer"; } // checking for floating point numbers else if (input.matches("\\d*[.]\\d+")) { dataType = "java.lang.Double"; } // checking for date format dd/mm/yyyy else if (input.matches( "\\d{2}[/]\\d{2}[/]\\d{4}")) { dataType = "java.util.Date"; } // checking for date format mm/dd/yyyy else if (input.matches( "\\d{2}[/]\\d{2}[/]\\d{4}")) { dataType = "java.util.Date"; } // checking for date format dd-mon-yy else if (input.matches( "\\d{2}[-]\\w{3}[-]\\d{2}")) { dataType = "java.util.Date"; } // checking for date format dd-mon-yyyy else if (input.matches( "\\d{2}[-]\\w{3}[-]\\d{4}")) { dataType = "java.util.Date"; } // checking for date format dd-month-yy else if (input.matches("\\d{2}[-]\\w+[-]\\d{2}")) { dataType = "java.util.Date"; } // checking for date format dd-month-yyyy else if (input.matches("\\d{2}[-]\\w+[-]\\d{4}")) { dataType = "java.util.Date"; } // checking for date format yyyy-mm-dd else if (input.matches( "\\d{4}[-]\\d{2}[-]\\d{2}")) { dataType = "java.util.Date"; } // checking for String else { dataType = "java.lang.String"; } System.out.println("The datatype of " + input + " is: " + dataType); }} |
Output
The datatype of 56.73 is: java.lang.Double
