如何将扫描仪输入转换为 integer？

Question

In Java, how, if possible, can I convert numerical scanner input (such as 2 or 87) into an integer variable? What I'm using now yields the error message:

    Exception in thread "main" java.lang.NumberFormatException: null
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.valueOf(Unknown Source)
    at diDecryption.Didecryption.main(Didecryption.java:226)

And this is the code I'm using to do it (pieced together, it's part of a much larger program):

    System.out.println("Enter first number");
    Scanner sc=new Scanner(System.in); 
    String name=sc.next();
    int result = Integer.valueOf(name);
    if (result / 2 == 1){
    System.out.println("a");

The purpose of the program is to decode an encrypted message. The input is numerical, and if I remove the string to int converter, the division does not work. How do I fix this?

Answer 1

System.out.println("Enter first number");
Scanner sc=new Scanner(System.in); 
String name=sc.next();
int result = Integer.parseInt(name);
if (result / 2 == 1){
System.out.println("a");

parseint changes it to a primitive int rather than an Integer object

Answer 2

In Java, how, if possible, can I convert numerical scanner input (such as 2 or 87) into an integer variable? What I'm using now yields the error message:

    Exception in thread "main" java.lang.NumberFormatException: null
    at java.lang.Integer.parseInt(Unknown Source)
    at java.lang.Integer.valueOf(Unknown Source)
    at diDecryption.Didecryption.main(Didecryption.java:226)

And this is the code I'm using to do it (pieced together, it's part of a much larger program):

    System.out.println("Enter first number");
    Scanner sc=new Scanner(System.in); 
    String name=sc.next();
    int result = Integer.valueOf(name);
    if (result / 2 == 1){
    System.out.println("a");

The purpose of the program is to decode an encrypted message. The input is numerical, and if I remove the string to int converter, the division does not work. How do I fix this?

Answer 3

In your stacktrace you have null as parameter in Integer.valueOf(name) . Seems your console produce some invalid input sequence. Try to check it with sc.hasNext() condition:

    System.out.println("Enter first number");
    Scanner sc = new Scanner(System.in);
    if (sc.hasNext()) {
        String name = sc.next();
        int result = Integer.parseInt(name);
        if (result / 2 == 1) {
            System.out.println("a");
        }
    }

Answer 4

Try

System.out.println("Enter first number");
Scanner sc=new Scanner(System.in); 
int name=sc.nextInt();
if ((name / 2) == 1)
System.out.println("a"); 

RUN

run:
Enter first number
2
a

Answer 5

Try this code

package exmaple;

import java.util.Scanner;

public class Parser {

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

        String name = in.next();

        try{
            int result = Integer.parseInt(name);
            if(result / 2 == 1) {
                System.out.println("a");
            }

        } catch(Exception exception) {

        }
        in.close();
    }

}

Answer 6

try

System.out.println("Enter first number");
Scanner sc=new Scanner(System.in); 
int result = sc.nextInt;
if (result / 2 == 1){
System.out.println("a");