java - equalsIgnoreCase 方法不适用于 JOptionPane(或 Scanner)输入

Question

    // ask user to enter name of state capital
    String answer = JOptionPane.showInputDialog("What is the capital of " + 
            question + "?");

    // verify name of state capital is in citiesarray
    boolean isPresent = false; int stateNum = 0;
    System.out.println(answer); // troubleshooting line
    for (int i = 0; i <= 49; i++) {
        String city = citiesarray[i];
        isPresent = answer.equalsIgnoreCase(city);
        System.out.println(city); // troubleshooting line
        System.out.println(answer.compareTo(city)); // troubleshooting line
        System.out.println(isPresent); // troubleshooting line
        if (isPresent == true) {
            stateNum = i; break;
        }
    }
    if (isPresent == false) {
        JOptionPane.showMessageDialog(null, "That is incorrect. Please try another round.");
        return;
    }

每当我运行此代码时，无论我输入什么大写字母，我都会在循环的每次迭代中得到所有错误的 boolean 值。似乎对于 equalsIgnoreCase 返回 true 的任何城市的 compareTo 输出始终为 -1，但我不知道如何使用它来识别和解决我的问题。

我尝试了几种不同的方法，发现使用 Scanner 时，只要答案不包含空格，它似乎就可以工作，但这对于 JOptionPane 来说似乎并不重要，而且无论如何，无论州首府在哪里，我都需要它工作。

Answer 1

发布的代码工作正常，在调整循环限制后，我只需添加两行并将上面的代码复制到主方法中:

public static void main(String[] args) {
    String[] citiesarray = { "New York", "Paris", "Berlin", "Brasilia" };  // not real ones, but wanted one with space
    String question = "somewhere";

    // ask user to enter name of state capital
    String answer = JOptionPane.showInputDialog("What is the capital of " + 
            question + "?");

    // verify name of state capital is in citiesarray
    boolean isPresent = false; int stateNum = 0;
    System.out.println(answer); // troubleshooting line
    for (int i = 0; i < citiesarray.length; i++) {
        String city = citiesarray[i];
        isPresent = answer.equalsIgnoreCase(city);
        System.out.println(city); // troubleshooting line
        System.out.println(answer.compareTo(city)); // troubleshooting line
        System.out.println(isPresent); // troubleshooting line
        if (isPresent == true) {
            stateNum = i; break;
        }
    }
    if (isPresent == false) {
        JOptionPane.showMessageDialog(null, "That is incorrect. Please try another round.");
        return;
    }
}

问题一定出在其他地方，可能是 citiesarray 的声明/初始化方式。