如何检查班级名称是否有效？

Question

Java中是否有方法检查字符串是否可以用作类名？

Answer 1

SourceVersion.isName 可用于检查完全限定名称.

如果不允许.s,则可以通过以下方式进行检查:

boolean isValidName (String className) {
    return SourceVersion.isIdentifier(className) && !SourceVersion.isKeyword(className);
}

Answer 2

很简单,使用该Class.forName(String name)方法,可用于测试如下:

public static boolean classExists(String className)
{
    try
    {
        Class.forName(className);
        return true;
    }
    catch(ClassNotFoundException ex)
    {
        return false;
    }
}

编辑:如果像dashrb所说的那样,你要求一种方法来确定一个String是否可以用作类名(而不是如果已经有一个类名),那么你需要的是一个组合我在上面发布的方法(由于你不能重复使用类的名称而翻转了布尔值),并结合检查来查看String是否是Java保留的关键字.我最近有一个类似的问题,并为它做了一个实用工具类,你可以在这里找到.我不会为你写的,但你基本上只需要添加支票!JavaKeywords.isKeyword(className).

编辑2:当然,如果您还要强制执行普遍接受的编码标准,您可以确保类名以大写字母开头,其中包含:

return Character.isUpperCase(className.charAt(0));

编辑3:正如Ted Hopp指出的那样,即使包含java关键字也会使类名无效,并且在我的某个生产应用程序中使用了JavaKeywords,我已经制作了一个更新版本,其中包含了containsKeyword(String toCheck)检查此可能性的方法.方法如下(请注意您也需要类中的关键字列表):

public static boolean containsKeyword(String toCheck)
{
    toCheck = toCheck.toLowerCase();
    for(String keyword : keywords)
    {
        if(toCheck.equals(keyword) || toCheck.endsWith("." + keyword) ||
           toCheck.startsWith(keyword + ".") || toCheck.contains("." + keyword + "."))
        {
            return true;
        }//End if
    }//End for
    return false;
}//End containsKeyword()

Answer 3

我使用了MrLore友情提供的java关键字列表.

private static final Set<String> javaKeywords = new HashSet<String>(Arrays.asList(
    "abstract",     "assert",        "boolean",      "break",           "byte",
    "case",         "catch",         "char",         "class",           "const",
    "continue",     "default",       "do",           "double",          "else",
    "enum",         "extends",       "false",        "final",           "finally",
    "float",        "for",           "goto",         "if",              "implements",
    "import",       "instanceof",    "int",          "interface",       "long",
    "native",       "new",           "null",         "package",         "private",
    "protected",    "public",        "return",       "short",           "static",
    "strictfp",     "super",         "switch",       "synchronized",    "this",
    "throw",        "throws",        "transient",    "true",            "try",
    "void",         "volatile",      "while"
));

private static final Pattern JAVA_CLASS_NAME_PART_PATTERN =
    Pattern.compile("[A-Za-z_$]+[a-zA-Z0-9_$]*");

public static boolean isJavaClassName(String text) {
    for (String part : text.split("\\.")) {
        if (javaKeywords.contains(part) ||
                !JAVA_CLASS_NAME_PART_PATTERN.matcher(part).matches()) {
            return false;
        }           
    }
    return text.length() > 0;
}

Answer 4

呀呀——

Class.forName(String className);

它返回与具有给定字符串名称的类或接口关联的 Class 对象。并抛出Exceptions

LinkageError - if the linkage fails
ExceptionInInitializerError - if the initialization provoked by this method fails
ClassNotFoundException - if the class cannot be located