java - 替换 Switch 语句中的字符

Question

以下是用下划线替换单词元音的代码:

String[] vowelArray = arrayInput;
    for (int x = 0; x < vowelArray.length; x++){
        for (int a = 0; a < vowelArray[x].length(); a++){
            switch (vowelArray[x].charAt(x)){
                case 'A': vowelArray[x].charAt(x) = "_";
                case 'a': vowelArray[x].charAt(x) = "_";
                case 'E': vowelArray[x].charAt(x) = "_";
                case 'e': vowelArray[x].charAt(x) = "_";
                case 'I': vowelArray[x].charAt(x) = "_";
                case 'i': vowelArray[x].charAt(x) = "_";
                case 'O': vowelArray[x].charAt(x) = "_";
                case 'o': vowelArray[x].charAt(x) = "_";
                case 'U': vowelArray[x].charAt(x) = "_";
                case 'u': vowelArray[x].charAt(x) = "_";
                case 'Y': vowelArray[x].charAt(x) = "_";
                case 'y': vowelArray[x].charAt(x) = "_";
            }
        }
    }

但是在编译时，我收到此错误:

Exception in thread "main" java.lang.Error: Unresolved compilation problems: The left-hand side of an assignment must be a variable

它出现在每种情况下的 switch 语句中。我做错了什么？

Answer 1

您无法更改 Java 中的String，它是一个不可变的对象。您可以做的是从String获取底层的char[]，修改数组，并创建一个新的String 与它(并且不要忘记用 break 结束每个 case 语句):

String[] vowelArray = arrayInput;
for (int x = 0; x < vowelArray.length; x++) {
    char[] chars = vowelArray[x].toCharArray();
    for (int a = 0; a < chars.length; a++) {
        switch (chars[a]) {
            case 'A': chars[a] = "_"; break;
            case 'a': chars[a] = "_"; break;
            case 'E': chars[a] = "_"; break;
            case 'e': chars[a] = "_"; break;
            case 'I': chars[a] = "_"; break;
            case 'i': chars[a] = "_"; break;
            case 'O': chars[a] = "_"; break;
            case 'o': chars[a] = "_"; break;
            case 'U': chars[a] = "_"; break;
            case 'u': chars[a] = "_"; break;
            case 'Y': chars[a] = "_"; break;
            case 'y': chars[a] = "_"; break;
        }
    }
    vowelArray[x] = new String(chars);
}

或者更简单，您可以使用 replaceAll() 方法来执行替换:

String[] vowelArray = arrayInput;
for (int x = 0; x < vowelArray.length; x++) {
    vowelArray[x] = vowelArray[x].replaceAll("[AaEeIiOoUuYy]", "_");
}