EqualsIgnoreCase()无法正常工作. [英] EqualsIgnoreCase() not working as intended.

问题描述

当我运行以下程序时，它只会打印

When i run the following program it prints only

equals says they are equal

但是从Java 8中的equalsIgnoreCase文档中，我们可以得到:

However From equalsIgnoreCase docs in java 8 we have :

如果将两个字符c1和c2视为相同，则忽略大小写至少满足以下条件之一:
•应用方法每个字符的java.lang.Character.toUpperCase(char)产生相同的结果

Two characters c1 and c2 are considered the same ignoring case if at least one of the following is true:
• Applying the method java.lang.Character.toUpperCase(char) to each character produces the same result

    public class Test {
    public static void main(String[] args) {

        String string1 = "abc\u00DF";
        String string2 = string1.toUpperCase();

        if (string1.equalsIgnoreCase(string2))
            System.out.println("equalsIgnoreCase says they are equal");

        if (string1.toUpperCase().equals(string2.toUpperCase()))
            System.out.println("equals says they are equal");

    }
}

所以我的问题是为什么该程序无法打印

So my question is why this program is not printing

equalsIgnoreCase says they are equal

与两个操作一样，使用大写字母.

As in both operations upper case charcters are used.

推荐答案

您正在使用/比较德国ß符号，其大写字母生成 SS ...因此您需要使用 Locale.German

You are using/comparing the german ß sign, its uppercase produce SS... so you need to use the Locale.German

if (string1.toUpperCase(Locale.GERMAN).equals(string2.toUpperCase(Locale.GERMAN)))

将返回true....

that will return true....

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