java - Scanner.next() 不会停止

Question

这个问题已经有答案了:

How do I compare strings in Java? (23 个回答)

已关闭 9 年前。

public class ElectronicCounter {

    public ElectronicCounter(User user)throws IOException{
        Scanner scanner = new Scanner(System.in);
        boolean done = false;
        loginName = user.getName();

        System.out.println("--------------------------------------------------------");
        System.out.println("Welcome to the Electronic-Sales Counter! ");

        while(!done){
            try{
                System.out.print("Please enter '1' to record sales or '2' to exit:");
                input = scanner.nextLine();
                System.out.println("bug");
                if(input=="1"){
                    System.out.println("Please enter a list of purchasing-product ID and number");
                    done = true;
                }
                else if(input=="2"){
                    System.out.println("<LOG> User " +loginName+ " has successfully logged off! ");
                    done = true;
                }
                else{
                    System.out.println("<LOG> Invalid command");
                }
            }
            catch (NoSuchElementException e){
                System.out.println("<LOG> No Such Element");
            }
            catch (IllegalStateException e){
                System.out.println("<LOG> IllegalState");
            }
        }
        scanner.close();
    }

    static String loginName;
    static String input;
}

当 scanner.nextLine() 时，扫描仪不会停止搜索 token 。被计算出来。我想问如何停止扫描仪等待输入？谢谢

Answer 1

决不使用==比较字符串。当使用 == 比较字符串对象时，您不是在比较它的值，而是在比较它的引用。

始终使用 equals 方法进行比较。

input.equals("2");