How to Check if the text read from keyboard Is integer or string or character?

Question about the task

Maximum of entered numbers

Java Syntax, Level 4, Lesson 5

Under discussion

The program must read integers from the keyboard until something else is entered, such as a string or a character. Display the maximum even number entered. If several numbers are entered, you must display any of them.

Example input:

Example output:
8

Requirements:

The program should read numbers from the keyboard.
The program should display a number on the screen.
The program should display the maximum even number of the integers entered.
If several maximum even numbers are entered, then you need to display any one of them.
If there is no even number among the entered characters, or only one non-numeric character is entered, then display the minimum possible value for an int.
You need to read data from the keyboard in a while loop.

package en.codegym.task.pro.task04.task0408; import java.util.Scanner; /* Maximum of entered numbers */ public class Solution { public static void main(String[] args) { Scanner scanner = new Scanner(System.in); boolean isExit = false; // int i; int a= 0 ; int b= 0; int maxEven = Integer.MIN_VALUE; while (!isExit) { String name = scanner.nextLine(); isExit = name.equals("e"); if(isExit) break; b = Integer.parseInt(name); if ((b % 2 == 0) && b > maxEven) maxEven = b; else continue; // System.out.println(a); // a = a + b; // System.out.println(a); } System.out.println(maxEven); } }

Comments (1)

Popular
New
Old

You must be signed in to leave a comment

Thomas

Level 41 , Bayreuth, Germany

27 November 2023, 08:00

If you use the Scanner class then it is not very difficult. It has a methods boolean hasNextInt() and in nextInt() You can combine them eg. in this way

int sum = 0;
Scanner console = new Scanner(System.in);

while (console.hasNextInt()) {
    sum += console.nextInt();
}

System.out.println(sum);

The wrapper types usually have static members that let you parse for numbers, like:

String unknown = "3";
// may throw an exception if the input is not a convertable value
int number = Integer.parseInt(unknown);
System.out.println("if you see this, then unknown is an int with the value: " + number);

or you come up with an own solution

String unknown = "12a3";
boolean isNumber = true;

for (int i = 0; i < unknown.length(); i++) {
    char current = unknown.charAt(i);
    if (current < '0' || current > '9') {
        isNumber = false;
        break;
    }
}

System.out.format("Is %s an int? %b", unknown, isNumber);