I'm surprised that no one suggested javax.lang.model.SourceVersion yet, because it's actually been around since Java 1.6.

If you need to check whether some string is a reserved keyword, you can just call:

SourceVersion.isKeyword(str)

And if you really need the full list of the reserved keywords, you can obtain it from the source code of that class:

private final static Set<String> keywords;
static {
    Set<String> s = new HashSet<String>();
    String [] kws = {
        "abstract", "continue",     "for",          "new",          "switch",
        "assert",   "default",      "if",           "package",      "synchronized",
        "boolean",  "do",           "goto",         "private",      "this",
        "break",    "double",       "implements",   "protected",    "throw",
        "byte",     "else",         "import",       "public",       "throws",
        "case",     "enum",         "instanceof",   "return",       "transient",
        "catch",    "extends",      "int",          "short",        "try",
        "char",     "final",        "interface",    "static",       "void",
        "class",    "finally",      "long",         "strictfp",     "volatile",
        "const",    "float",        "native",       "super",        "while",
        // literals
        "null",     "true",         "false"
    };
    for(String kw : kws)
        s.add(kw);
    keywords = Collections.unmodifiableSet(s);
}

Caution: the above source code is from Java 1.8, so don't just copy & paste from this post if you're using a different version of Java. In fact, it's probably not a good idea to copy it at all — they made the field private for good reason — you probably don't want to have to keep it up-to-date for every new Java release. But if you absolutely must have it, then copy it from the source code in your own JDK distro, keeping in mind that you might have to manually keep updating it later.