Java 字符串在分配给 Scanner NextLine() 时未存储相同的值

Question

我的代码的控制台处理程序遇到了问题。不知道赋值给s.nextLine();后读取in会不会丢弃in的当前值。不确定是否有任何其他因素会影响字符串在一行中被正确读取，而在下一行中被错误读取。

提前致谢！

while (loop == true) {
        Scanner s = new Scanner(System.in);
        String a = s.nextLine();
        String in = a;
        info("User input: " + in, "DEBUG", 0);
        if (in == "kill") {
            info("Are you sure you would like to kill the running instance? [Y/N]", "CONSOLE", 0);
            if (in == "Y" || in == "y") {
                info("Starting KILL method.", "CONSOLE", 0);
                s.close();
                loop = false
            } else if (in == "N" || in == "n") {
                info("Cancelled.", "CONSOLE", 0);
            } else {
                info("Illegal arguements given. Cancelled.", "CONSOLE", 0);
            }

        } else {
            info("Illegal Arguements given.", "CONSOLE", 0);
        }

    }

当我在控制台中输入 kill 时，它给了我这个：

[info @ DEBUG/0]> User input: kill
[info @ CONSOLE/0]> Illegal Arguements given.

Answer 1

您应该使用 .equals() 方法检查字符串（和其他对象）是否相等，而不是使用 == 运算符。

Answer 2

对于字符串比较，您应该使用 .equals:

while (loop == true) {
        Scanner s = new Scanner(System.in);
        String a = s.nextLine();
        String in = a;
        info("User input: " + in, "DEBUG", 0);
        if ("kill".equals(in)) {
            info("Are you sure you would like to kill the running instance? [Y/N]", "CONSOLE", 0);
            if ("Y".equals(in) || "y".equals(in)) {
                info("Starting KILL method.", "CONSOLE", 0);
                s.close();
                loop = false
            } else if ("N".equals(in) || "n".equals(in)) {
                info("Cancelled.", "CONSOLE", 0);
            } else {
                info("Illegal arguments given. Cancelled.", "CONSOLE", 0);
            }

        } else {
            info("Illegal arguments given.", "CONSOLE", 0);
        }
    }

Java 字符串在分配给 Scanner NextLine() 时未存储相同的值

Java String not storing same value when assigned to Scanner NextLine()

java

system.in

java.util.scanner