我的代码有什么问题（Java 字符输入初学者）

Question

import java.util.Scanner;
public class Application {

public static void main(String[] args) {
    do {
    System.out.println("What is the command keyword to exit a loop in Java?\na. int\nb. continue\nc. break\nd. exit\nEnter your choice");
    Scanner ans = new Scanner(System.in);
    char ans = sc.next().charAt(0);
    if(ans=='c')
        System.out.println("Correct");
    else
        System.out.println("Wrong! Presss Y to try again.");
    Scanner redo = new Scanner(System.in);
    char redo = sc.next().charAt(0);
    }
    while(redo=='y');
}

}

I'm just starting to learn Java, can you please tell me what's wrong in my code and how to improve it? Thanks

This is the error I receive.

Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
Duplicate local variable ans
sc cannot be resolved
Duplicate local variable redo
sc cannot be resolved
redo cannot be resolved to a variable

at Application.main(Application.java:9)

Answer 1

Think you want to get smth like this:

public class Application {

    public static void main(String[] args) {
        char redo;
        do {
            System.out.println("What is the command keyword to exit a loop in Java?\na. int\nb. continue\nc. break\nd. exit\nEnter your choice");
            Scanner scanner = new Scanner(System.in);
            char ans = scanner.next().charAt(0);
            if (ans == 'c') {
                System.out.println("Correct");
                break;
            }
            else {
                System.out.println("Wrong! Presss Y to try again.");
                redo = scanner.next().charAt(0);
            }
        }
        while (redo == 'y');
    }

}

Problems in your implementation:

Wrong variable definition

Attempt to redefine ans variable leads to the compilation error. Use different variable names. For ex:

Scanner scanner = new Scanner(System.in);
char ans = scanner.next().charAt(0);

instead of this

Scanner ans = new Scanner(System.in);
char ans = sc.next().charAt(0);

Probably you want to break the loop if answer is correct

So better to add break when ans=='c' :

if (ans == 'c') {
   System.out.println("Correct");
   break;
}

While condition variable definition

Define redo variable before do-while loop block, otherwise you'll get compilation error

Answer 2

Duplicate local variable "ans" in the following 2 statement. rename anyone of then to another.

Scanner ans = new Scanner(System.in);
   char ans = sc.next().charAt(0);