Discuss / Java / 难度越来越大了，这一章跟前面的反射和异常处理联系非常紧密，需要大量用到前面的知识，看廖老师的例子慢慢理了一遍再敲出来
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难度越来越大了，这一章跟前面的反射和异常处理联系非常紧密，需要大量用到前面的知识，看廖老师的例子慢慢理了一遍再敲出来

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_我是来微博看美女的

#1 Created at ... [Delete] [Delete and Lock User] 
// TODO:
				if (value instanceof String) {
					String s = (String) value;
					if (s.length()<range.min() || s.length()>range.max()) {
						throw new IllegalArgumentException("Invalid field: " + field.getName());
					}
				}
				else if (value instanceof Integer) {
					Integer n = (Integer) value;
					if (n<range.min() || n>range.max()) {
						throw new IllegalArgumentException("Invalid field: " + field.getName());
					}
				}

运行结果：

Person {Person: name=Bob, city=Beijing, age=20} checked ok.
Person {Person: name=, city=Shanghai, age=20} checked failed: java.lang.IllegalArgumentException: Invalid field: name
Person {Person: name=Alice, city=Shanghai, age=199} checked failed: java.lang.IllegalArgumentException: Invalid field: age

静谧伯爵

#2 Created at ... [Delete] [Delete and Lock User] 
else if (value instanceof Integer) {
		Integer n = (Integer) value;

请问，这里为什么要用Integer，而不用int?

鳄鱼搓背三百一次

#3 Created at ... [Delete] [Delete and Lock User]

value是Object类

Object value = field.get(person);

Joker.fu_95

#4 Created at ... [Delete] [Delete and Lock User]

因为Object是class，int是基本数据类型，强转的话还是Integer好些

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