Ahmed Helal Ahmed Ahmed Helal Ahmed - 11 months ago 65
Java Question

hasNextDouble method give true with integer the same as double

First of all, see this code:

package test;

import java.util.*;

public class hasnext {
public static void main(String[] args) {
Scanner s = new Scanner(System.in);

If i enter integer number I will get true ex : 5

If i enter real number I will get true then crash ex 1.5

The method gives true either the number of type double or integer is that right and why?

Answer Source

From the javadoc for Scanner.hasNextDouble():

Returns true if the next token in this scanner's input can be interpreted as a double value using the nextDouble() method.

An integer can be interpreted as a double. For instance, in Java you can cast an integer to a double, with no loss of information.

Apparently a double can't be interpreted as an integer. Most likely because in most cases, the double would lose information by converting from a double to an integer.